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authorJuergen Gross <jgross@suse.com>2015-01-12 08:05:08 +0300
committerDavid Vrabel <david.vrabel@citrix.com>2015-01-12 13:09:40 +0300
commitf241b0b891c903da2465b7a98eaf650784e666da (patch)
treeff0134e6a0dd55e5066719de73dac85d8ea972fe /arch
parent82c92ed1357bca22a5d637fbb93dab3eb18a8e8c (diff)
downloadlinux-f241b0b891c903da2465b7a98eaf650784e666da.tar.xz
xen: correct race in alloc_p2m_pmd()
When allocating a new pmd for the linear mapped p2m list a check is done for not introducing another pmd when this just happened on another cpu. In this case the old pte pointer was returned which points to the p2m_missing or p2m_identity page. The correct value would be the pointer to the found new page. Signed-off-by: Juergen Gross <jgross@suse.com> Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/p2m.c9
1 files changed, 3 insertions, 6 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index ff4ebd820603..70fb5075c901 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -439,10 +439,9 @@ EXPORT_SYMBOL_GPL(get_phys_to_machine);
* a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
* pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
*/
-static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *ptep, pte_t *pte_pg)
+static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
{
pte_t *ptechk;
- pte_t *pteret = ptep;
pte_t *pte_newpg[PMDS_PER_MID_PAGE];
pmd_t *pmdp;
unsigned int level;
@@ -476,8 +475,6 @@ static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *ptep, pte_t *pte_pg)
if (ptechk == pte_pg) {
set_pmd(pmdp,
__pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
- if (vaddr == (addr & ~(PMD_SIZE - 1)))
- pteret = pte_offset_kernel(pmdp, addr);
pte_newpg[i] = NULL;
}
@@ -491,7 +488,7 @@ static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *ptep, pte_t *pte_pg)
vaddr += PMD_SIZE;
}
- return pteret;
+ return lookup_address(addr, &level);
}
/*
@@ -520,7 +517,7 @@ static bool alloc_p2m(unsigned long pfn)
if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
/* PMD level is missing, allocate a new one */
- ptep = alloc_p2m_pmd(addr, ptep, pte_pg);
+ ptep = alloc_p2m_pmd(addr, pte_pg);
if (!ptep)
return false;
}