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xen/grant-table: Avoid m2p_override during mapping 

The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
for blkback and future netback patches it just cause a lock contention, as
those pages never go to userspace. Therefore this series does the following:
- the original functions were renamed to __gnttab_[un]map_refs, with a new
  parameter m2p_override
- based on m2p_override either they follow the original behaviour, or just set
  the private flag and call set_phys_to_machine
- gnttab_[un]map_refs are now a wrapper to call __gnttab_[un]map_refs with
  m2p_override false
- a new function gnttab_[un]map_refs_userspace provides the old behaviour

It also removes a stray space from page.h and change ret to 0 if
XENFEAT_auto_translated_physmap, as that is the only possible return value
there.

v2:
- move the storing of the old mfn in page->index to gnttab_map_refs
- move the function header update to a separate patch

v3:
- a new approach to retain old behaviour where it needed
- squash the patches into one

v4:
- move out the common bits from m2p* functions, and pass pfn/mfn as parameter
- clear page->private before doing anything with the page, so m2p_find_override
  won't race with this

v5:
- change return value handling in __gnttab_[un]map_refs
- remove a stray space in page.h
- add detail why ret = 0 now at some places

v6:
- don't pass pfn to m2p* functions, just get it locally

Signed-off-by: Zoltan Kiss <zoltan.kiss@citrix.com>
Suggested-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Zoltan Kiss 2014-01-23 21:23:44 +00:00 committed by Konrad Rzeszutek Wilk
parent 47c542050d
commit 08ece5bb23
6 changed files with 101 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/x86/include/asm/xen/page.h
View File

@ -52,7 +52,8 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s,
extern int m2p_add_override(unsigned long mfn, struct page *page,
struct gnttab_map_grant_ref *kmap_op);
extern int m2p_remove_override(struct page *page,
struct gnttab_map_grant_ref *kmap_op);
struct gnttab_map_grant_ref *kmap_op,
unsigned long mfn);
extern struct page *m2p_find_override(unsigned long mfn);
extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn);
@ -121,7 +122,7 @@ static inline unsigned long mfn_to_pfn(unsigned long mfn)
pfn = m2p_find_override_pfn(mfn, ~0);
}
/*
/*
* pfn is ~0 if there are no entries in the m2p for mfn or if the
* entry doesn't map back to the mfn and m2p_override doesn't have a
* valid entry for it.

17
arch/x86/xen/p2m.c
View File

@ -899,13 +899,6 @@ int m2p_add_override(unsigned long mfn, struct page *page,
"m2p_add_override: pfn %lx not mapped", pfn))
return -EINVAL;
}
WARN_ON(PagePrivate(page));
SetPagePrivate(page);
set_page_private(page, mfn);
page->index = pfn_to_mfn(pfn);
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
return -ENOMEM;
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
@ -944,19 +937,16 @@ int m2p_add_override(unsigned long mfn, struct page *page,
}
EXPORT_SYMBOL_GPL(m2p_add_override);
int m2p_remove_override(struct page *page,
struct gnttab_map_grant_ref *kmap_op)
struct gnttab_map_grant_ref *kmap_op,
unsigned long mfn)
{
unsigned long flags;
unsigned long mfn;
unsigned long pfn;
unsigned long uninitialized_var(address);
unsigned level;
pte_t *ptep = NULL;
pfn = page_to_pfn(page);
mfn = get_phys_to_machine(pfn);
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
return -EINVAL;
if (!PageHighMem(page)) {
address = (unsigned long)__va(pfn << PAGE_SHIFT);
@ -970,10 +960,7 @@ int m2p_remove_override(struct page *page,
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
WARN_ON(!PagePrivate(page));
ClearPagePrivate(page);
set_phys_to_machine(pfn, page->index);
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs;

15
drivers/block/xen-blkback/blkback.c
View File

@ -285,8 +285,7 @@ static void free_persistent_gnts(struct xen_blkif *blkif, struct rb_root *root,
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST ||
!rb_next(&persistent_gnt->node)) {
ret = gnttab_unmap_refs(unmap, NULL, pages,
segs_to_unmap);
ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
segs_to_unmap = 0;
@ -321,8 +320,7 @@ static void unmap_purged_grants(struct work_struct *work)
pages[segs_to_unmap] = persistent_gnt->page;
if (++segs_to_unmap == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
ret = gnttab_unmap_refs(unmap, NULL, pages,
segs_to_unmap);
ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
segs_to_unmap = 0;
@ -330,7 +328,7 @@ static void unmap_purged_grants(struct work_struct *work)
kfree(persistent_gnt);
}
if (segs_to_unmap > 0) {
ret = gnttab_unmap_refs(unmap, NULL, pages, segs_to_unmap);
ret = gnttab_unmap_refs(unmap, pages, segs_to_unmap);
BUG_ON(ret);
put_free_pages(blkif, pages, segs_to_unmap);
}
@ -670,15 +668,14 @@ static void xen_blkbk_unmap(struct xen_blkif *blkif,
GNTMAP_host_map, pages[i]->handle);
pages[i]->handle = BLKBACK_INVALID_HANDLE;
if (++invcount == BLKIF_MAX_SEGMENTS_PER_REQUEST) {
ret = gnttab_unmap_refs(unmap, NULL, unmap_pages,
invcount);
ret = gnttab_unmap_refs(unmap, unmap_pages, invcount);
BUG_ON(ret);
put_free_pages(blkif, unmap_pages, invcount);
invcount = 0;
}
}
if (invcount) {
ret = gnttab_unmap_refs(unmap, NULL, unmap_pages, invcount);
ret = gnttab_unmap_refs(unmap, unmap_pages, invcount);
BUG_ON(ret);
put_free_pages(blkif, unmap_pages, invcount);
}
@ -740,7 +737,7 @@ again:
}
if (segs_to_map) {
ret = gnttab_map_refs(map, NULL, pages_to_gnt, segs_to_map);
ret = gnttab_map_refs(map, pages_to_gnt, segs_to_map);
BUG_ON(ret);
}

13
drivers/xen/gntdev.c
View File

@ -284,8 +284,10 @@ static int map_grant_pages(struct grant_map *map)
}
pr_debug("map %d+%d\n", map->index, map->count);
err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
map->pages, map->count);
err = gnttab_map_refs_userspace(map->map_ops,
use_ptemod ? map->kmap_ops : NULL,
map->pages,
map->count);
if (err)
return err;
@ -315,9 +317,10 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
}
}
err = gnttab_unmap_refs(map->unmap_ops + offset,
use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset,
pages);
err = gnttab_unmap_refs_userspace(map->unmap_ops + offset,
use_ptemod ? map->kmap_ops + offset : NULL,
map->pages + offset,
pages);
if (err)
return err;

89
drivers/xen/grant-table.c
View File

@ -928,15 +928,17 @@ void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
}
EXPORT_SYMBOL_GPL(gnttab_batch_copy);
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
int __gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
struct page **pages, unsigned int count,
bool m2p_override)
{
int i, ret;
bool lazy = false;
pte_t *pte;
unsigned long mfn;
unsigned long mfn, pfn;
BUG_ON(kmap_ops && !m2p_override);
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
if (ret)
return ret;
@ -955,10 +957,12 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,
map_ops[i].dev_bus_addr >> PAGE_SHIFT);
}
return ret;
return 0;
}
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
if (m2p_override &&
!in_interrupt() &&
paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
arch_enter_lazy_mmu_mode();
lazy = true;
}
@ -975,8 +979,20 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
} else {
mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
}
ret = m2p_add_override(mfn, pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
pfn = page_to_pfn(pages[i]);
WARN_ON(PagePrivate(pages[i]));
SetPagePrivate(pages[i]);
set_page_private(pages[i], mfn);
pages[i]->index = pfn_to_mfn(pfn);
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
ret = -ENOMEM;
goto out;
}
if (m2p_override)
ret = m2p_add_override(mfn, pages[i], kmap_ops ?
&kmap_ops[i] : NULL);
if (ret)
goto out;
}
@ -987,15 +1003,32 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
return ret;
}
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
struct page **pages, unsigned int count)
{
return __gnttab_map_refs(map_ops, NULL, pages, count, false);
}
EXPORT_SYMBOL_GPL(gnttab_map_refs);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
int gnttab_map_refs_userspace(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
return __gnttab_map_refs(map_ops, kmap_ops, pages, count, true);
}
EXPORT_SYMBOL_GPL(gnttab_map_refs_userspace);
int __gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
struct page **pages, unsigned int count,
bool m2p_override)
{
int i, ret;
bool lazy = false;
unsigned long pfn, mfn;
BUG_ON(kmap_ops && !m2p_override);
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
if (ret)
return ret;
@ -1006,17 +1039,33 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
INVALID_P2M_ENTRY);
}
return ret;
return 0;
}
if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
if (m2p_override &&
!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);
pfn = page_to_pfn(pages[i]);
mfn = get_phys_to_machine(pfn);
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
ret = -EINVAL;
goto out;
}
set_page_private(pages[i], INVALID_P2M_ENTRY);
WARN_ON(!PagePrivate(pages[i]));
ClearPagePrivate(pages[i]);
set_phys_to_machine(pfn, pages[i]->index);
if (m2p_override)
ret = m2p_remove_override(pages[i],
kmap_ops ?
&kmap_ops[i] : NULL,
mfn);
if (ret)
goto out;
}
@ -1027,8 +1076,22 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
return ret;
}
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *map_ops,
struct page **pages, unsigned int count)
{
return __gnttab_unmap_refs(map_ops, NULL, pages, count, false);
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
int gnttab_unmap_refs_userspace(struct gnttab_unmap_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
return __gnttab_unmap_refs(map_ops, kmap_ops, pages, count, true);
}
EXPORT_SYMBOL_GPL(gnttab_unmap_refs_userspace);
static unsigned nr_status_frames(unsigned nr_grant_frames)
{
BUG_ON(grefs_per_grant_frame == 0);

8
include/xen/grant_table.h
View File

@ -191,11 +191,15 @@ void gnttab_free_auto_xlat_frames(void);
#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))
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 gnttab_map_refs_userspace(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_map_grant_ref *kunmap_ops,
struct page **pages, unsigned int count);
int gnttab_unmap_refs_userspace(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_map_grant_ref *kunmap_ops,
struct page **pages, unsigned int count);
/* Perform a batch of grant map/copy operations. Retry every batch slot
* for which the hypervisor returns GNTST_eagain. This is typically due