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authorDavid Vrabel <david.vrabel@citrix.com>2014-03-25 10:38:37 +0000
committerDavid Vrabel <david.vrabel@citrix.com>2014-03-25 11:11:42 +0000
commit5926f87fdaad4be3ed10cec563bf357915e55a86 (patch)
treef44ee105eb3a1bb59ea098788c6949004438cf41 /arch/x86/xen/mmu.c
parent09ed3d5ba06137913960f9c9385f71fc384193ab (diff)
Revert "xen: properly account for _PAGE_NUMA during xen pte translations"
This reverts commit a9c8e4beeeb64c22b84c803747487857fe424b68. PTEs in Xen PV guests must contain machine addresses if _PAGE_PRESENT is set and pseudo-physical addresses is _PAGE_PRESENT is clear. This is because during a domain save/restore (migration) the page table entries are "canonicalised" and uncanonicalised". i.e., MFNs are converted to PFNs during domain save so that on a restore the page table entries may be rewritten with the new MFNs on the destination. This canonicalisation is only done for PTEs that are present. This change resulted in writing PTEs with MFNs if _PAGE_PROTNONE (or _PAGE_NUMA) was set but _PAGE_PRESENT was clear. These PTEs would be migrated as-is which would result in unexpected behaviour in the destination domain. Either a) the MFN would be translated to the wrong PFN/page; b) setting the _PAGE_PRESENT bit would clear the PTE because the MFN is no longer owned by the domain; or c) the present bit would not get set. Symptoms include "Bad page" reports when munmapping after migrating a domain. Signed-off-by: David Vrabel <david.vrabel@citrix.com> Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: <stable@vger.kernel.org> [3.12+]
Diffstat (limited to 'arch/x86/xen/mmu.c')
-rw-r--r--arch/x86/xen/mmu.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 256282e7888b..2423ef04ffea 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -365,7 +365,7 @@ void xen_ptep_modify_prot_commit(struct mm_struct *mm, unsigned long addr,
/* Assume pteval_t is equivalent to all the other *val_t types. */
static pteval_t pte_mfn_to_pfn(pteval_t val)
{
- if (pteval_present(val)) {
+ if (val & _PAGE_PRESENT) {
unsigned long mfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
unsigned long pfn = mfn_to_pfn(mfn);
@@ -381,7 +381,7 @@ static pteval_t pte_mfn_to_pfn(pteval_t val)
static pteval_t pte_pfn_to_mfn(pteval_t val)
{
- if (pteval_present(val)) {
+ if (val & _PAGE_PRESENT) {
unsigned long pfn = (val & PTE_PFN_MASK) >> PAGE_SHIFT;
pteval_t flags = val & PTE_FLAGS_MASK;
unsigned long mfn;