linux/drivers/xen/grant-table.c

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/******************************************************************************
* grant_table.c
*
* Granting foreign access to our memory reservation.
*
* Copyright (c) 2005-2006, Christopher Clark
* Copyright (c) 2004-2005, K A Fraser
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation; or, when distributed
* separately from the Linux kernel or incorporated into other
* software packages, subject to the following license:
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this source file (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy, modify,
* merge, publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/mm.h>
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 09:04:11 +01:00
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
#include <linux/io.h>
xen/gndev: Xen backend support for paged out grant targets V4. Since Xen-4.2, hvm domains may have portions of their memory paged out. When a foreign domain (such as dom0) attempts to map these frames, the map will initially fail. The hypervisor returns a suitable errno, and kicks an asynchronous page-in operation carried out by a helper. The foreign domain is expected to retry the mapping operation until it eventually succeeds. The foreign domain is not put to sleep because itself could be the one running the pager assist (typical scenario for dom0). This patch adds support for this mechanism for backend drivers using grant mapping and copying operations. Specifically, this covers the blkback and gntdev drivers (which map foreign grants), and the netback driver (which copies foreign grants). * Add a retry method for grants that fail with GNTST_eagain (i.e. because the target foreign frame is paged out). * Insert hooks with appropriate wrappers in the aforementioned drivers. The retry loop is only invoked if the grant operation status is GNTST_eagain. It guarantees to leave a new status code different from GNTST_eagain. Any other status code results in identical code execution as before. The retry loop performs 256 attempts with increasing time intervals through a 32 second period. It uses msleep to yield while waiting for the next retry. V2 after feedback from David Vrabel: * Explicit MAX_DELAY instead of wrap-around delay into zero * Abstract GNTST_eagain check into core grant table code for netback module. V3 after feedback from Ian Campbell: * Add placeholder in array of grant table error descriptions for unrelated error code we jump over. * Eliminate single map and retry macro in favor of a generic batch flavor. * Some renaming. * Bury most implementation in grant_table.c, cleaner interface. V4 rebased on top of sync of Xen grant table interface headers. Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> Acked-by: Ian Campbell <ian.campbell@citrix.com> [v5: Fixed whitespace issues] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-14 16:26:59 +02:00
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <xen/xen.h>
#include <xen/interface/xen.h>
#include <xen/page.h>
#include <xen/grant_table.h>
#include <xen/interface/memory.h>
#include <xen/hvc-console.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/interface.h>
#include <asm/pgtable.h>
#include <asm/sync_bitops.h>
/* External tools reserve first few grant table entries. */
#define NR_RESERVED_ENTRIES 8
#define GNTTAB_LIST_END 0xffffffff
static grant_ref_t **gnttab_list;
static unsigned int nr_grant_frames;
static unsigned int boot_max_nr_grant_frames;
static int gnttab_free_count;
static grant_ref_t gnttab_free_head;
static DEFINE_SPINLOCK(gnttab_list_lock);
unsigned long xen_hvm_resume_frames;
EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
static union {
struct grant_entry_v1 *v1;
union grant_entry_v2 *v2;
void *addr;
} gnttab_shared;
/*This is a structure of function pointers for grant table*/
struct gnttab_ops {
/*
* Mapping a list of frames for storing grant entries. Frames parameter
* is used to store grant table address when grant table being setup,
* nr_gframes is the number of frames to map grant table. Returning
* GNTST_okay means success and negative value means failure.
*/
int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
/*
* Release a list of frames which are mapped in map_frames for grant
* entry status.
*/
void (*unmap_frames)(void);
/*
* Introducing a valid entry into the grant table, granting the frame of
* this grant entry to domain for accessing or transfering. Ref
* parameter is reference of this introduced grant entry, domid is id of
* granted domain, frame is the page frame to be granted, and flags is
* status of the grant entry to be updated.
*/
void (*update_entry)(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags);
/*
* Stop granting a grant entry to domain for accessing. Ref parameter is
* reference of a grant entry whose grant access will be stopped,
* readonly is not in use in this function. If the grant entry is
* currently mapped for reading or writing, just return failure(==0)
* directly and don't tear down the grant access. Otherwise, stop grant
* access for this entry and return success(==1).
*/
int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
/*
* Stop granting a grant entry to domain for transfer. Ref parameter is
* reference of a grant entry whose grant transfer will be stopped. If
* tranfer has not started, just reclaim the grant entry and return
* failure(==0). Otherwise, wait for the transfer to complete and then
* return the frame.
*/
unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
/*
* Query the status of a grant entry. Ref parameter is reference of
* queried grant entry, return value is the status of queried entry.
* Detailed status(writing/reading) can be gotten from the return value
* by bit operations.
*/
int (*query_foreign_access)(grant_ref_t ref);
/*
* Grant a domain to access a range of bytes within the page referred by
* an available grant entry. Ref parameter is reference of a grant entry
* which will be sub-page accessed, domid is id of grantee domain, frame
* is frame address of subpage grant, flags is grant type and flag
* information, page_off is offset of the range of bytes, and length is
* length of bytes to be accessed.
*/
void (*update_subpage_entry)(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off, unsigned length);
/*
* Redirect an available grant entry on domain A to another grant
* reference of domain B, then allow domain C to use grant reference
* of domain B transitively. Ref parameter is an available grant entry
* reference on domain A, domid is id of domain C which accesses grant
* entry transitively, flags is grant type and flag information,
* trans_domid is id of domain B whose grant entry is finally accessed
* transitively, trans_gref is grant entry transitive reference of
* domain B.
*/
void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags,
domid_t trans_domid, grant_ref_t trans_gref);
};
static struct gnttab_ops *gnttab_interface;
/*This reflects status of grant entries, so act as a global value*/
static grant_status_t *grstatus;
static int grant_table_version;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
static int grefs_per_grant_frame;
static struct gnttab_free_callback *gnttab_free_callback_list;
static int gnttab_expand(unsigned int req_entries);
#define RPP (PAGE_SIZE / sizeof(grant_ref_t))
#define SPP (PAGE_SIZE / sizeof(grant_status_t))
static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
{
return &gnttab_list[(entry) / RPP][(entry) % RPP];
}
/* This can be used as an l-value */
#define gnttab_entry(entry) (*__gnttab_entry(entry))
static int get_free_entries(unsigned count)
{
unsigned long flags;
int ref, rc = 0;
grant_ref_t head;
spin_lock_irqsave(&gnttab_list_lock, flags);
if ((gnttab_free_count < count) &&
((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
spin_unlock_irqrestore(&gnttab_list_lock, flags);
return rc;
}
ref = head = gnttab_free_head;
gnttab_free_count -= count;
while (count-- > 1)
head = gnttab_entry(head);
gnttab_free_head = gnttab_entry(head);
gnttab_entry(head) = GNTTAB_LIST_END;
spin_unlock_irqrestore(&gnttab_list_lock, flags);
return ref;
}
static void do_free_callbacks(void)
{
struct gnttab_free_callback *callback, *next;
callback = gnttab_free_callback_list;
gnttab_free_callback_list = NULL;
while (callback != NULL) {
next = callback->next;
if (gnttab_free_count >= callback->count) {
callback->next = NULL;
callback->fn(callback->arg);
} else {
callback->next = gnttab_free_callback_list;
gnttab_free_callback_list = callback;
}
callback = next;
}
}
static inline void check_free_callbacks(void)
{
if (unlikely(gnttab_free_callback_list))
do_free_callbacks();
}
static void put_free_entry(grant_ref_t ref)
{
unsigned long flags;
spin_lock_irqsave(&gnttab_list_lock, flags);
gnttab_entry(ref) = gnttab_free_head;
gnttab_free_head = ref;
gnttab_free_count++;
check_free_callbacks();
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
/*
* Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
* Introducing a valid entry into the grant table:
* 1. Write ent->domid.
* 2. Write ent->frame:
* GTF_permit_access: Frame to which access is permitted.
* GTF_accept_transfer: Pseudo-phys frame slot being filled by new
* frame, or zero if none.
* 3. Write memory barrier (WMB).
* 4. Write ent->flags, inc. valid type.
*/
static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags)
{
gnttab_shared.v1[ref].domid = domid;
gnttab_shared.v1[ref].frame = frame;
wmb();
gnttab_shared.v1[ref].flags = flags;
}
static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
unsigned long frame, unsigned flags)
{
gnttab_shared.v2[ref].hdr.domid = domid;
gnttab_shared.v2[ref].full_page.frame = frame;
wmb();
gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
}
/*
* Public grant-issuing interface functions
*/
void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
unsigned long frame, int readonly)
{
gnttab_interface->update_entry(ref, domid, frame,
GTF_permit_access | (readonly ? GTF_readonly : 0));
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
int readonly)
{
int ref;
ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off, unsigned length)
{
gnttab_shared.v2[ref].sub_page.frame = frame;
gnttab_shared.v2[ref].sub_page.page_off = page_off;
gnttab_shared.v2[ref].sub_page.length = length;
gnttab_shared.v2[ref].hdr.domid = domid;
wmb();
gnttab_shared.v2[ref].hdr.flags =
GTF_permit_access | GTF_sub_page | flags;
}
int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off,
unsigned length)
{
if (flags & (GTF_accept_transfer | GTF_reading |
GTF_writing | GTF_transitive))
return -EPERM;
if (gnttab_interface->update_subpage_entry == NULL)
return -ENOSYS;
gnttab_interface->update_subpage_entry(ref, domid, frame, flags,
page_off, length);
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref);
int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
int flags, unsigned page_off,
unsigned length)
{
int ref, rc;
ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags,
page_off, length);
if (rc < 0) {
put_free_entry(ref);
return rc;
}
return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage);
bool gnttab_subpage_grants_available(void)
{
return gnttab_interface->update_subpage_entry != NULL;
}
EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
int flags, domid_t trans_domid,
grant_ref_t trans_gref)
{
gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
gnttab_shared.v2[ref].transitive.gref = trans_gref;
gnttab_shared.v2[ref].hdr.domid = domid;
wmb();
gnttab_shared.v2[ref].hdr.flags =
GTF_permit_access | GTF_transitive | flags;
}
int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
int flags, domid_t trans_domid,
grant_ref_t trans_gref)
{
if (flags & (GTF_accept_transfer | GTF_reading |
GTF_writing | GTF_sub_page))
return -EPERM;
if (gnttab_interface->update_trans_entry == NULL)
return -ENOSYS;
gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
trans_gref);
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
domid_t trans_domid,
grant_ref_t trans_gref)
{
int ref, rc;
ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags,
trans_domid, trans_gref);
if (rc < 0) {
put_free_entry(ref);
return rc;
}
return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
bool gnttab_trans_grants_available(void)
{
return gnttab_interface->update_trans_entry != NULL;
}
EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
static int gnttab_query_foreign_access_v1(grant_ref_t ref)
{
return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
}
static int gnttab_query_foreign_access_v2(grant_ref_t ref)
{
return grstatus[ref] & (GTF_reading|GTF_writing);
}
int gnttab_query_foreign_access(grant_ref_t ref)
{
return gnttab_interface->query_foreign_access(ref);
}
EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
{
u16 flags, nflags;
u16 *pflags;
pflags = &gnttab_shared.v1[ref].flags;
nflags = *pflags;
do {
flags = nflags;
if (flags & (GTF_reading|GTF_writing))
return 0;
} while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
return 1;
}
static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
{
gnttab_shared.v2[ref].hdr.flags = 0;
mb();
if (grstatus[ref] & (GTF_reading|GTF_writing)) {
return 0;
} else {
/* The read of grstatus needs to have acquire
semantics. On x86, reads already have
that, and we just need to protect against
compiler reorderings. On other
architectures we may need a full
barrier. */
#ifdef CONFIG_X86
barrier();
#else
mb();
#endif
}
return 1;
}
static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
{
return gnttab_interface->end_foreign_access_ref(ref, readonly);
}
int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
{
if (_gnttab_end_foreign_access_ref(ref, readonly))
return 1;
pr_warn("WARNING: g.e. %#x still in use!\n", ref);
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
struct deferred_entry {
struct list_head list;
grant_ref_t ref;
bool ro;
uint16_t warn_delay;
struct page *page;
};
static LIST_HEAD(deferred_list);
static void gnttab_handle_deferred(unsigned long);
static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
static void gnttab_handle_deferred(unsigned long unused)
{
unsigned int nr = 10;
struct deferred_entry *first = NULL;
unsigned long flags;
spin_lock_irqsave(&gnttab_list_lock, flags);
while (nr--) {
struct deferred_entry *entry
= list_first_entry(&deferred_list,
struct deferred_entry, list);
if (entry == first)
break;
list_del(&entry->list);
spin_unlock_irqrestore(&gnttab_list_lock, flags);
if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
put_free_entry(entry->ref);
if (entry->page) {
pr_debug("freeing g.e. %#x (pfn %#lx)\n",
entry->ref, page_to_pfn(entry->page));
__free_page(entry->page);
} else
pr_info("freeing g.e. %#x\n", entry->ref);
kfree(entry);
entry = NULL;
} else {
if (!--entry->warn_delay)
pr_info("g.e. %#x still pending\n", entry->ref);
if (!first)
first = entry;
}
spin_lock_irqsave(&gnttab_list_lock, flags);
if (entry)
list_add_tail(&entry->list, &deferred_list);
else if (list_empty(&deferred_list))
break;
}
if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
deferred_timer.expires = jiffies + HZ;
add_timer(&deferred_timer);
}
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
struct page *page)
{
struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
const char *what = KERN_WARNING "leaking";
if (entry) {
unsigned long flags;
entry->ref = ref;
entry->ro = readonly;
entry->page = page;
entry->warn_delay = 60;
spin_lock_irqsave(&gnttab_list_lock, flags);
list_add_tail(&entry->list, &deferred_list);
if (!timer_pending(&deferred_timer)) {
deferred_timer.expires = jiffies + HZ;
add_timer(&deferred_timer);
}
spin_unlock_irqrestore(&gnttab_list_lock, flags);
what = KERN_DEBUG "deferring";
}
printk("%s g.e. %#x (pfn %#lx)\n",
what, ref, page ? page_to_pfn(page) : -1);
}
void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
unsigned long page)
{
if (gnttab_end_foreign_access_ref(ref, readonly)) {
put_free_entry(ref);
if (page != 0)
free_page(page);
} else
gnttab_add_deferred(ref, readonly,
page ? virt_to_page(page) : NULL);
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
{
int ref;
ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
unsigned long pfn)
{
gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;
pflags = &gnttab_shared.v1[ref].flags;
/*
* If a transfer is not even yet started, try to reclaim the grant
* reference and return failure (== 0).
*/
while (!((flags = *pflags) & GTF_transfer_committed)) {
if (sync_cmpxchg(pflags, flags, 0) == flags)
return 0;
cpu_relax();
}
/* If a transfer is in progress then wait until it is completed. */
while (!(flags & GTF_transfer_completed)) {
flags = *pflags;
cpu_relax();
}
rmb(); /* Read the frame number /after/ reading completion status. */
frame = gnttab_shared.v1[ref].frame;
BUG_ON(frame == 0);
return frame;
}
static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
{
unsigned long frame;
u16 flags;
u16 *pflags;
pflags = &gnttab_shared.v2[ref].hdr.flags;
/*
* If a transfer is not even yet started, try to reclaim the grant
* reference and return failure (== 0).
*/
while (!((flags = *pflags) & GTF_transfer_committed)) {
if (sync_cmpxchg(pflags, flags, 0) == flags)
return 0;
cpu_relax();
}
/* If a transfer is in progress then wait until it is completed. */
while (!(flags & GTF_transfer_completed)) {
flags = *pflags;
cpu_relax();
}
rmb(); /* Read the frame number /after/ reading completion status. */
frame = gnttab_shared.v2[ref].full_page.frame;
BUG_ON(frame == 0);
return frame;
}
unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
{
return gnttab_interface->end_foreign_transfer_ref(ref);
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
{
unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
put_free_entry(ref);
return frame;
}
EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
void gnttab_free_grant_reference(grant_ref_t ref)
{
put_free_entry(ref);
}
EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
void gnttab_free_grant_references(grant_ref_t head)
{
grant_ref_t ref;
unsigned long flags;
int count = 1;
if (head == GNTTAB_LIST_END)
return;
spin_lock_irqsave(&gnttab_list_lock, flags);
ref = head;
while (gnttab_entry(ref) != GNTTAB_LIST_END) {
ref = gnttab_entry(ref);
count++;
}
gnttab_entry(ref) = gnttab_free_head;
gnttab_free_head = head;
gnttab_free_count += count;
check_free_callbacks();
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
{
int h = get_free_entries(count);
if (h < 0)
return -ENOSPC;
*head = h;
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
int gnttab_empty_grant_references(const grant_ref_t *private_head)
{
return (*private_head == GNTTAB_LIST_END);
}
EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
int gnttab_claim_grant_reference(grant_ref_t *private_head)
{
grant_ref_t g = *private_head;
if (unlikely(g == GNTTAB_LIST_END))
return -ENOSPC;
*private_head = gnttab_entry(g);
return g;
}
EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
void gnttab_release_grant_reference(grant_ref_t *private_head,
grant_ref_t release)
{
gnttab_entry(release) = *private_head;
*private_head = release;
}
EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
void gnttab_request_free_callback(struct gnttab_free_callback *callback,
void (*fn)(void *), void *arg, u16 count)
{
unsigned long flags;
struct gnttab_free_callback *cb;
spin_lock_irqsave(&gnttab_list_lock, flags);
/* Check if the callback is already on the list */
cb = gnttab_free_callback_list;
while (cb) {
if (cb == callback)
goto out;
cb = cb->next;
}
callback->fn = fn;
callback->arg = arg;
callback->count = count;
callback->next = gnttab_free_callback_list;
gnttab_free_callback_list = callback;
check_free_callbacks();
out:
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
{
struct gnttab_free_callback **pcb;
unsigned long flags;
spin_lock_irqsave(&gnttab_list_lock, flags);
for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
if (*pcb == callback) {
*pcb = callback->next;
break;
}
}
spin_unlock_irqrestore(&gnttab_list_lock, flags);
}
EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
static int grow_gnttab_list(unsigned int more_frames)
{
unsigned int new_nr_grant_frames, extra_entries, i;
unsigned int nr_glist_frames, new_nr_glist_frames;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
BUG_ON(grefs_per_grant_frame == 0);
new_nr_grant_frames = nr_grant_frames + more_frames;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
extra_entries = more_frames * grefs_per_grant_frame;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
new_nr_glist_frames =
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
(new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
if (!gnttab_list[i])
goto grow_nomem;
}
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
for (i = grefs_per_grant_frame * nr_grant_frames;
i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
gnttab_entry(i) = i + 1;
gnttab_entry(i) = gnttab_free_head;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
gnttab_free_count += extra_entries;
nr_grant_frames = new_nr_grant_frames;
check_free_callbacks();
return 0;
grow_nomem:
for ( ; i >= nr_glist_frames; i--)
free_page((unsigned long) gnttab_list[i]);
return -ENOMEM;
}
static unsigned int __max_nr_grant_frames(void)
{
struct gnttab_query_size query;
int rc;
query.dom = DOMID_SELF;
rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
if ((rc < 0) || (query.status != GNTST_okay))
return 4; /* Legacy max supported number of frames */
return query.max_nr_frames;
}
unsigned int gnttab_max_grant_frames(void)
{
unsigned int xen_max = __max_nr_grant_frames();
if (xen_max > boot_max_nr_grant_frames)
return boot_max_nr_grant_frames;
return xen_max;
}
EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
xen/gndev: Xen backend support for paged out grant targets V4. Since Xen-4.2, hvm domains may have portions of their memory paged out. When a foreign domain (such as dom0) attempts to map these frames, the map will initially fail. The hypervisor returns a suitable errno, and kicks an asynchronous page-in operation carried out by a helper. The foreign domain is expected to retry the mapping operation until it eventually succeeds. The foreign domain is not put to sleep because itself could be the one running the pager assist (typical scenario for dom0). This patch adds support for this mechanism for backend drivers using grant mapping and copying operations. Specifically, this covers the blkback and gntdev drivers (which map foreign grants), and the netback driver (which copies foreign grants). * Add a retry method for grants that fail with GNTST_eagain (i.e. because the target foreign frame is paged out). * Insert hooks with appropriate wrappers in the aforementioned drivers. The retry loop is only invoked if the grant operation status is GNTST_eagain. It guarantees to leave a new status code different from GNTST_eagain. Any other status code results in identical code execution as before. The retry loop performs 256 attempts with increasing time intervals through a 32 second period. It uses msleep to yield while waiting for the next retry. V2 after feedback from David Vrabel: * Explicit MAX_DELAY instead of wrap-around delay into zero * Abstract GNTST_eagain check into core grant table code for netback module. V3 after feedback from Ian Campbell: * Add placeholder in array of grant table error descriptions for unrelated error code we jump over. * Eliminate single map and retry macro in favor of a generic batch flavor. * Some renaming. * Bury most implementation in grant_table.c, cleaner interface. V4 rebased on top of sync of Xen grant table interface headers. Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> Acked-by: Ian Campbell <ian.campbell@citrix.com> [v5: Fixed whitespace issues] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-14 16:26:59 +02:00
/* Handling of paged out grant targets (GNTST_eagain) */
#define MAX_DELAY 256
static inline void
gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
const char *func)
{
unsigned delay = 1;
do {
BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
if (*status == GNTST_eagain)
msleep(delay++);
} while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
if (delay >= MAX_DELAY) {
pr_err("%s: %s eagain grant\n", func, current->comm);
xen/gndev: Xen backend support for paged out grant targets V4. Since Xen-4.2, hvm domains may have portions of their memory paged out. When a foreign domain (such as dom0) attempts to map these frames, the map will initially fail. The hypervisor returns a suitable errno, and kicks an asynchronous page-in operation carried out by a helper. The foreign domain is expected to retry the mapping operation until it eventually succeeds. The foreign domain is not put to sleep because itself could be the one running the pager assist (typical scenario for dom0). This patch adds support for this mechanism for backend drivers using grant mapping and copying operations. Specifically, this covers the blkback and gntdev drivers (which map foreign grants), and the netback driver (which copies foreign grants). * Add a retry method for grants that fail with GNTST_eagain (i.e. because the target foreign frame is paged out). * Insert hooks with appropriate wrappers in the aforementioned drivers. The retry loop is only invoked if the grant operation status is GNTST_eagain. It guarantees to leave a new status code different from GNTST_eagain. Any other status code results in identical code execution as before. The retry loop performs 256 attempts with increasing time intervals through a 32 second period. It uses msleep to yield while waiting for the next retry. V2 after feedback from David Vrabel: * Explicit MAX_DELAY instead of wrap-around delay into zero * Abstract GNTST_eagain check into core grant table code for netback module. V3 after feedback from Ian Campbell: * Add placeholder in array of grant table error descriptions for unrelated error code we jump over. * Eliminate single map and retry macro in favor of a generic batch flavor. * Some renaming. * Bury most implementation in grant_table.c, cleaner interface. V4 rebased on top of sync of Xen grant table interface headers. Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> Acked-by: Ian Campbell <ian.campbell@citrix.com> [v5: Fixed whitespace issues] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-14 16:26:59 +02:00
*status = GNTST_bad_page;
}
}
void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
{
struct gnttab_map_grant_ref *op;
if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
BUG();
for (op = batch; op < batch + count; op++)
if (op->status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
&op->status, __func__);
}
EXPORT_SYMBOL_GPL(gnttab_batch_map);
void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
{
struct gnttab_copy *op;
if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
BUG();
for (op = batch; op < batch + count; op++)
if (op->status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_copy, op,
&op->status, __func__);
}
EXPORT_SYMBOL_GPL(gnttab_batch_copy);
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
bool lazy = false;
pte_t *pte;
unsigned long mfn;
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
if (ret)
return ret;
xen/gndev: Xen backend support for paged out grant targets V4. Since Xen-4.2, hvm domains may have portions of their memory paged out. When a foreign domain (such as dom0) attempts to map these frames, the map will initially fail. The hypervisor returns a suitable errno, and kicks an asynchronous page-in operation carried out by a helper. The foreign domain is expected to retry the mapping operation until it eventually succeeds. The foreign domain is not put to sleep because itself could be the one running the pager assist (typical scenario for dom0). This patch adds support for this mechanism for backend drivers using grant mapping and copying operations. Specifically, this covers the blkback and gntdev drivers (which map foreign grants), and the netback driver (which copies foreign grants). * Add a retry method for grants that fail with GNTST_eagain (i.e. because the target foreign frame is paged out). * Insert hooks with appropriate wrappers in the aforementioned drivers. The retry loop is only invoked if the grant operation status is GNTST_eagain. It guarantees to leave a new status code different from GNTST_eagain. Any other status code results in identical code execution as before. The retry loop performs 256 attempts with increasing time intervals through a 32 second period. It uses msleep to yield while waiting for the next retry. V2 after feedback from David Vrabel: * Explicit MAX_DELAY instead of wrap-around delay into zero * Abstract GNTST_eagain check into core grant table code for netback module. V3 after feedback from Ian Campbell: * Add placeholder in array of grant table error descriptions for unrelated error code we jump over. * Eliminate single map and retry macro in favor of a generic batch flavor. * Some renaming. * Bury most implementation in grant_table.c, cleaner interface. V4 rebased on top of sync of Xen grant table interface headers. Signed-off-by: Andres Lagar-Cavilla <andres@lagarcavilla.org> Acked-by: Ian Campbell <ian.campbell@citrix.com> [v5: Fixed whitespace issues] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2012-09-14 16:26:59 +02:00
/* Retry eagain maps */
for (i = 0; i < count; i++)
if (map_ops[i].status == GNTST_eagain)
gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
&map_ops[i].status, __func__);
if (xen_feature(XENFEAT_auto_translated_physmap))
return ret;
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
/* Do not add to override if the map failed. */
if (map_ops[i].status)
continue;
xen/p2m/m2p/gnttab: Support GNTMAP_host_map in the M2P override. We only supported the M2P (and P2M) override only for the GNTMAP_contains_pte type mappings. Meaning that we grants operations would "contain the machine address of the PTE to update" If the flag is unset, then the grant operation is "contains a host virtual address". The latter case means that the Hypervisor takes care of updating our page table (specifically the PTE entry) with the guest's MFN. As such we should not try to do anything with the PTE. Previous to this patch we would try to clear the PTE which resulted in Xen hypervisor being upset with us: (XEN) mm.c:1066:d0 Attempt to implicitly unmap a granted PTE c0100000ccc59067 (XEN) domain_crash called from mm.c:1067 (XEN) Domain 0 (vcpu#0) crashed on cpu#3: (XEN) ----[ Xen-4.0-110228 x86_64 debug=y Not tainted ]---- and crashing us. This patch allows us to inhibit the PTE clearing in the PV guest if the GNTMAP_contains_pte is not set. On the m2p_remove_override path we provide the same parameter. Sadly in the grant-table driver we do not have a mechanism to tell m2p_remove_override whether to clear the PTE or not. Since the grant-table driver is used by user-space, we can safely assume that it operates only on PTE's. Hence the implementation for it to work on !GNTMAP_contains_pte returns -EOPNOTSUPP. In the future we can implement the support for this. It will require some extra accounting structure to keep track of the page[i], and the flag. [v1: Added documentation details, made it return -EOPNOTSUPP instead of trying to do a half-way implementation] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-02-28 23:58:48 +01:00
if (map_ops[i].flags & GNTMAP_contains_pte) {
pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
(map_ops[i].host_addr & ~PAGE_MASK));
xen/p2m/m2p/gnttab: Support GNTMAP_host_map in the M2P override. We only supported the M2P (and P2M) override only for the GNTMAP_contains_pte type mappings. Meaning that we grants operations would "contain the machine address of the PTE to update" If the flag is unset, then the grant operation is "contains a host virtual address". The latter case means that the Hypervisor takes care of updating our page table (specifically the PTE entry) with the guest's MFN. As such we should not try to do anything with the PTE. Previous to this patch we would try to clear the PTE which resulted in Xen hypervisor being upset with us: (XEN) mm.c:1066:d0 Attempt to implicitly unmap a granted PTE c0100000ccc59067 (XEN) domain_crash called from mm.c:1067 (XEN) Domain 0 (vcpu#0) crashed on cpu#3: (XEN) ----[ Xen-4.0-110228 x86_64 debug=y Not tainted ]---- and crashing us. This patch allows us to inhibit the PTE clearing in the PV guest if the GNTMAP_contains_pte is not set. On the m2p_remove_override path we provide the same parameter. Sadly in the grant-table driver we do not have a mechanism to tell m2p_remove_override whether to clear the PTE or not. Since the grant-table driver is used by user-space, we can safely assume that it operates only on PTE's. Hence the implementation for it to work on !GNTMAP_contains_pte returns -EOPNOTSUPP. In the future we can implement the support for this. It will require some extra accounting structure to keep track of the page[i], and the flag. [v1: Added documentation details, made it return -EOPNOTSUPP instead of trying to do a half-way implementation] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-02-28 23:58:48 +01:00
mfn = pte_mfn(*pte);
} else {
mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
xen/p2m/m2p/gnttab: Support GNTMAP_host_map in the M2P override. We only supported the M2P (and P2M) override only for the GNTMAP_contains_pte type mappings. Meaning that we grants operations would "contain the machine address of the PTE to update" If the flag is unset, then the grant operation is "contains a host virtual address". The latter case means that the Hypervisor takes care of updating our page table (specifically the PTE entry) with the guest's MFN. As such we should not try to do anything with the PTE. Previous to this patch we would try to clear the PTE which resulted in Xen hypervisor being upset with us: (XEN) mm.c:1066:d0 Attempt to implicitly unmap a granted PTE c0100000ccc59067 (XEN) domain_crash called from mm.c:1067 (XEN) Domain 0 (vcpu#0) crashed on cpu#3: (XEN) ----[ Xen-4.0-110228 x86_64 debug=y Not tainted ]---- and crashing us. This patch allows us to inhibit the PTE clearing in the PV guest if the GNTMAP_contains_pte is not set. On the m2p_remove_override path we provide the same parameter. Sadly in the grant-table driver we do not have a mechanism to tell m2p_remove_override whether to clear the PTE or not. Since the grant-table driver is used by user-space, we can safely assume that it operates only on PTE's. Hence the implementation for it to work on !GNTMAP_contains_pte returns -EOPNOTSUPP. In the future we can implement the support for this. It will require some extra accounting structure to keep track of the page[i], and the flag. [v1: Added documentation details, made it return -EOPNOTSUPP instead of trying to do a half-way implementation] Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2011-02-28 23:58:48 +01:00
}
ret = m2p_add_override(mfn, pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
return ret;
}
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
}
EXPORT_SYMBOL_GPL(gnttab_map_refs);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
bool lazy = false;
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
if (ret)
return ret;
if (xen_feature(XENFEAT_auto_translated_physmap))
return ret;
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
for (i = 0; i < count; i++) {
ret = m2p_remove_override(pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
return ret;
}
if (lazy)
arch_leave_lazy_mmu_mode();
return ret;
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
static unsigned nr_status_frames(unsigned nr_grant_frames)
{
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
BUG_ON(grefs_per_grant_frame == 0);
return (nr_grant_frames * grefs_per_grant_frame + SPP - 1) / SPP;
}
static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
{
int rc;
rc = arch_gnttab_map_shared(frames, nr_gframes,
gnttab_max_grant_frames(),
&gnttab_shared.addr);
BUG_ON(rc);
return 0;
}
static void gnttab_unmap_frames_v1(void)
{
arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
}
static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes)
{
uint64_t *sframes;
unsigned int nr_sframes;
struct gnttab_get_status_frames getframes;
int rc;
nr_sframes = nr_status_frames(nr_gframes);
/* No need for kzalloc as it is initialized in following hypercall
* GNTTABOP_get_status_frames.
*/
sframes = kmalloc(nr_sframes * sizeof(uint64_t), GFP_ATOMIC);
if (!sframes)
return -ENOMEM;
getframes.dom = DOMID_SELF;
getframes.nr_frames = nr_sframes;
set_xen_guest_handle(getframes.frame_list, sframes);
rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
&getframes, 1);
if (rc == -ENOSYS) {
kfree(sframes);
return -ENOSYS;
}
BUG_ON(rc || getframes.status);
rc = arch_gnttab_map_status(sframes, nr_sframes,
nr_status_frames(gnttab_max_grant_frames()),
&grstatus);
BUG_ON(rc);
kfree(sframes);
rc = arch_gnttab_map_shared(frames, nr_gframes,
gnttab_max_grant_frames(),
&gnttab_shared.addr);
BUG_ON(rc);
return 0;
}
static void gnttab_unmap_frames_v2(void)
{
arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
}
static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
{
struct gnttab_setup_table setup;
xen_pfn_t *frames;
unsigned int nr_gframes = end_idx + 1;
int rc;
if (xen_hvm_domain()) {
struct xen_add_to_physmap xatp;
unsigned int i = end_idx;
rc = 0;
/*
* Loop backwards, so that the first hypercall has the largest
* index, ensuring that the table will grow only once.
*/
do {
xatp.domid = DOMID_SELF;
xatp.idx = i;
xatp.space = XENMAPSPACE_grant_table;
xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
if (rc != 0) {
pr_warn("grant table add_to_physmap failed, err=%d\n",
rc);
break;
}
} while (i-- > start_idx);
return rc;
}
/* No need for kzalloc as it is initialized in following hypercall
* GNTTABOP_setup_table.
*/
frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
if (!frames)
return -ENOMEM;
setup.dom = DOMID_SELF;
setup.nr_frames = nr_gframes;
set_xen_guest_handle(setup.frame_list, frames);
rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
if (rc == -ENOSYS) {
kfree(frames);
return -ENOSYS;
}
BUG_ON(rc || setup.status);
rc = gnttab_interface->map_frames(frames, nr_gframes);
kfree(frames);
return rc;
}
static struct gnttab_ops gnttab_v1_ops = {
.map_frames = gnttab_map_frames_v1,
.unmap_frames = gnttab_unmap_frames_v1,
.update_entry = gnttab_update_entry_v1,
.end_foreign_access_ref = gnttab_end_foreign_access_ref_v1,
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v1,
.query_foreign_access = gnttab_query_foreign_access_v1,
};
static struct gnttab_ops gnttab_v2_ops = {
.map_frames = gnttab_map_frames_v2,
.unmap_frames = gnttab_unmap_frames_v2,
.update_entry = gnttab_update_entry_v2,
.end_foreign_access_ref = gnttab_end_foreign_access_ref_v2,
.end_foreign_transfer_ref = gnttab_end_foreign_transfer_ref_v2,
.query_foreign_access = gnttab_query_foreign_access_v2,
.update_subpage_entry = gnttab_update_subpage_entry_v2,
.update_trans_entry = gnttab_update_trans_entry_v2,
};
static void gnttab_request_version(void)
{
int rc;
struct gnttab_set_version gsv;
if (xen_hvm_domain())
gsv.version = 1;
else
gsv.version = 2;
rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
if (rc == 0 && gsv.version == 2) {
grant_table_version = 2;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
grefs_per_grant_frame = PAGE_SIZE / sizeof(union grant_entry_v2);
gnttab_interface = &gnttab_v2_ops;
} else if (grant_table_version == 2) {
/*
* If we've already used version 2 features,
* but then suddenly discover that they're not
* available (e.g. migrating to an older
* version of Xen), almost unbounded badness
* can happen.
*/
panic("we need grant tables version 2, but only version 1 is available");
} else {
grant_table_version = 1;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
gnttab_interface = &gnttab_v1_ops;
}
pr_info("Grant tables using version %d layout\n", grant_table_version);
}
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
static int gnttab_setup(void)
{
unsigned int max_nr_gframes;
max_nr_gframes = gnttab_max_grant_frames();
if (max_nr_gframes < nr_grant_frames)
return -ENOSYS;
if (xen_pv_domain())
return gnttab_map(0, nr_grant_frames - 1);
if (gnttab_shared.addr == NULL) {
gnttab_shared.addr = xen_remap(xen_hvm_resume_frames,
PAGE_SIZE * max_nr_gframes);
if (gnttab_shared.addr == NULL) {
pr_warn("Failed to ioremap gnttab share frames!\n");
return -ENOMEM;
}
}
gnttab_map(0, nr_grant_frames - 1);
return 0;
}
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
int gnttab_resume(void)
{
gnttab_request_version();
return gnttab_setup();
}
int gnttab_suspend(void)
{
gnttab_interface->unmap_frames();
return 0;
}
static int gnttab_expand(unsigned int req_entries)
{
int rc;
unsigned int cur, extra;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
BUG_ON(grefs_per_grant_frame == 0);
cur = nr_grant_frames;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
extra = ((req_entries + (grefs_per_grant_frame-1)) /
grefs_per_grant_frame);
if (cur + extra > gnttab_max_grant_frames())
return -ENOSPC;
rc = gnttab_map(cur, cur + extra - 1);
if (rc == 0)
rc = grow_gnttab_list(extra);
return rc;
}
int gnttab_init(void)
{
int i;
unsigned int max_nr_glist_frames, nr_glist_frames;
unsigned int nr_init_grefs;
int ret;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
gnttab_request_version();
nr_grant_frames = 1;
boot_max_nr_grant_frames = __max_nr_grant_frames();
/* Determine the maximum number of frames required for the
* grant reference free list on the current hypervisor.
*/
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
BUG_ON(grefs_per_grant_frame == 0);
max_nr_glist_frames = (boot_max_nr_grant_frames *
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
grefs_per_grant_frame / RPP);
gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
GFP_KERNEL);
if (gnttab_list == NULL)
return -ENOMEM;
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
for (i = 0; i < nr_glist_frames; i++) {
gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
if (gnttab_list[i] == NULL) {
ret = -ENOMEM;
goto ini_nomem;
}
}
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
if (gnttab_setup() < 0) {
ret = -ENODEV;
goto ini_nomem;
}
xen/grant-table: correctly initialize grant table version 1 Commit 85ff6acb075a484780b3d763fdf41596d8fc0970 (xen/granttable: Grant tables V2 implementation) changed the GREFS_PER_GRANT_FRAME macro from a constant to a conditional expression. The expression depends on grant_table_version being appropriately set. Unfortunately, at init time grant_table_version will be 0. The GREFS_PER_GRANT_FRAME conditional expression checks for "grant_table_version == 1", and therefore returns the number of grant references per frame for v2. This causes gnttab_init() to allocate fewer pages for gnttab_list, as a frame can old half the number of v2 entries than v1 entries. After gnttab_resume() is called, grant_table_version is appropriately set. nr_init_grefs will then be miscalculated and gnttab_free_count will hold a value larger than the actual number of free gref entries. If a guest is heavily utilizing improperly initialized v1 grant tables, memory corruption can occur. One common manifestation is corruption of the vmalloc list, resulting in a poisoned pointer derefrence when accessing /proc/meminfo or /proc/vmallocinfo: [ 40.770064] BUG: unable to handle kernel paging request at 0000200200001407 [ 40.770083] IP: [<ffffffff811a6fb0>] get_vmalloc_info+0x70/0x110 [ 40.770102] PGD 0 [ 40.770107] Oops: 0000 [#1] SMP [ 40.770114] CPU 10 This patch introduces a static variable, grefs_per_grant_frame, to cache the calculated value. gnttab_init() now calls gnttab_request_version() early so that grant_table_version and grefs_per_grant_frame can be appropriately set. A few BUG_ON()s have been added to prevent this type of bug from reoccurring in the future. Signed-off-by: Matt Wilson <msw@amazon.com> Reviewed-and-Tested-by: Steven Noonan <snoonan@amazon.com> Acked-by: Ian Campbell <Ian.Campbell@citrix.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Annie Li <annie.li@oracle.com> Cc: xen-devel@lists.xen.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org # v3.3 and newer Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
2013-01-15 14:21:27 +01:00
nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
gnttab_entry(i) = i + 1;
gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
gnttab_free_head = NR_RESERVED_ENTRIES;
printk("Grant table initialized\n");
return 0;
ini_nomem:
for (i--; i >= 0; i--)
free_page((unsigned long)gnttab_list[i]);
kfree(gnttab_list);
return ret;
}
EXPORT_SYMBOL_GPL(gnttab_init);
static int __gnttab_init(void)
{
/* Delay grant-table initialization in the PV on HVM case */
if (xen_hvm_domain())
return 0;
if (!xen_pv_domain())
return -ENODEV;
return gnttab_init();
}
core_initcall(__gnttab_init);