OpenE2K
/
linux
6
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

xen pv-on-hvm: add pfn_is_ram helper for kdump 

Register pfn_is_ram helper speed up reading /proc/vmcore in the kdump
kernel. See commit message of 997c136f51 ("fs/proc/vmcore.c: add hook
to read_from_oldmem() to check for non-ram pages") for details.

It makes use of a new hvmop HVMOP_get_mem_type which was introduced in
xen 4.2 (23298:26413986e6e0) and backported to 4.1.1.

The new function is currently only enabled for reading /proc/vmcore.
Later it will be used also for the kexec kernel. Since that requires
more changes in the generic kernel make it static for the time being.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Olaf Hering 2012-10-01 21:18:01 +02:00 committed by Konrad Rzeszutek Wilk
parent 9b6934a3b4
commit 34b6f01a79
2 changed files with 60 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

41
arch/x86/xen/mmu.c
View File

@ -47,6 +47,7 @@
#include <linux/gfp.h>
#include <linux/memblock.h>
#include <linux/seq_file.h>
#include <linux/crash_dump.h>
#include <trace/events/xen.h>
@ -2381,6 +2382,43 @@ void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
#ifdef CONFIG_XEN_PVHVM
#ifdef CONFIG_PROC_VMCORE
/*
* This function is used in two contexts:
* - the kdump kernel has to check whether a pfn of the crashed kernel
* was a ballooned page. vmcore is using this function to decide
* whether to access a pfn of the crashed kernel.
* - the kexec kernel has to check whether a pfn was ballooned by the
* previous kernel. If the pfn is ballooned, handle it properly.
* Returns 0 if the pfn is not backed by a RAM page, the caller may
* handle the pfn special in this case.
*/
static int xen_oldmem_pfn_is_ram(unsigned long pfn)
{
struct xen_hvm_get_mem_type a = {
.domid = DOMID_SELF,
.pfn = pfn,
};
int ram;
if (HYPERVISOR_hvm_op(HVMOP_get_mem_type, &a))
return -ENXIO;
switch (a.mem_type) {
case HVMMEM_mmio_dm:
ram = 0;
break;
case HVMMEM_ram_rw:
case HVMMEM_ram_ro:
default:
ram = 1;
break;
}
return ram;
}
#endif
static void xen_hvm_exit_mmap(struct mm_struct *mm)
{
struct xen_hvm_pagetable_dying a;
@ -2411,6 +2449,9 @@ void __init xen_hvm_init_mmu_ops(void)
{
if (is_pagetable_dying_supported())
pv_mmu_ops.exit_mmap = xen_hvm_exit_mmap;
#ifdef CONFIG_PROC_VMCORE
register_oldmem_pfn_is_ram(&xen_oldmem_pfn_is_ram);
#endif
}
#endif

19
include/xen/interface/hvm/hvm_op.h
View File

@ -43,4 +43,23 @@ struct xen_hvm_pagetable_dying {
typedef struct xen_hvm_pagetable_dying xen_hvm_pagetable_dying_t;
DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_pagetable_dying_t);
enum hvmmem_type_t {
HVMMEM_ram_rw, /* Normal read/write guest RAM */
HVMMEM_ram_ro, /* Read-only; writes are discarded */
HVMMEM_mmio_dm, /* Reads and write go to the device model */
};
#define HVMOP_get_mem_type 15
/* Return hvmmem_type_t for the specified pfn. */
struct xen_hvm_get_mem_type {
/* Domain to be queried. */
domid_t domid;
/* OUT variable. */
uint16_t mem_type;
uint16_t pad[2]; /* align next field on 8-byte boundary */
/* IN variable. */
uint64_t pfn;
};
DEFINE_GUEST_HANDLE_STRUCT(xen_hvm_get_mem_type);
#endif /* __XEN_PUBLIC_HVM_HVM_OP_H__ */