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Fix two bugs that cause x86 PV guest crashes.

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1. Ballooning a 32-bit guest would eventually crash it.
 
 2. Revert a broken fix for a regression with NUMA_BALACING.  The bad
    fix caused PV guests to crash after migration.  This is not ideal
    but unpicking the madness that is _PAGE_NUMA == _PAGE_PROTNONE will
    take a while longer.
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Merge tag 'stable/for-linus-3.14-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull Xen bugfixes from David Vrabel:
 "Fix two bugs that cause x86 PV guest crashes.

  1. Ballooning a 32-bit guest would eventually crash it.

  2. Revert a broken fix for a regression with NUMA_BALACING.  The bad
     fix caused PV guests to crash after migration.  This is not ideal
     but unpicking the madness that is _PAGE_NUMA == _PAGE_PROTNONE will
     take a while longer"

* tag 'stable/for-linus-3.14-rc8-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  Revert "xen: properly account for _PAGE_NUMA during xen pte translations"
  xen/balloon: flush persistent kmaps in correct position
This commit is contained in:
Linus Torvalds 2014-03-28 10:52:05 -07:00
commit 81250437a5
3 changed files with 23 additions and 21 deletions
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14
arch/x86/include/asm/pgtable.h
View File

@ -445,20 +445,10 @@ static inline int pte_same(pte_t a, pte_t b)
return a.pte == b.pte;
}
static inline int pteval_present(pteval_t pteval)
{
/*
* Yes Linus, _PAGE_PROTNONE == _PAGE_NUMA. Expressing it this
* way clearly states that the intent is that protnone and numa
* hinting ptes are considered present for the purposes of
* pagetable operations like zapping, protection changes, gup etc.
*/
return pteval & (_PAGE_PRESENT | _PAGE_PROTNONE | _PAGE_NUMA);
}
static inline int pte_present(pte_t a)
{
return pteval_present(pte_flags(a));
return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE |
_PAGE_NUMA);
}
#define pte_accessible pte_accessible

4
arch/x86/xen/mmu.c
View File

@ -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;

26
drivers/xen/balloon.c
View File

@ -399,12 +399,26 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
state = BP_EAGAIN;
break;
}
pfn = page_to_pfn(page);
frame_list[i] = pfn_to_mfn(pfn);
scrub_page(page);
frame_list[i] = page_to_pfn(page);
}
/*
* Ensure that ballooned highmem pages don't have kmaps.
*
* Do this before changing the p2m as kmap_flush_unused()
* reads PTEs to obtain pages (and hence needs the original
* p2m entry).
*/
kmap_flush_unused();
/* Update direct mapping, invalidate P2M, and add to balloon. */
for (i = 0; i < nr_pages; i++) {
pfn = frame_list[i];
frame_list[i] = pfn_to_mfn(pfn);
page = pfn_to_page(pfn);
#ifdef CONFIG_XEN_HAVE_PVMMU
/*
* Ballooned out frames are effectively replaced with
@ -429,11 +443,9 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
}
#endif
balloon_append(pfn_to_page(pfn));
balloon_append(page);
}
/* Ensure that ballooned highmem pages don't have kmaps. */
kmap_flush_unused();
flush_tlb_all();
set_xen_guest_handle(reservation.extent_start, frame_list);