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>
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index ff4ebd8..70fb507 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -439,10 +439,9 @@
* 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 @@
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 @@
vaddr += PMD_SIZE;
}
- return pteret;
+ return lookup_address(addr, &level);
}
/*
@@ -520,7 +517,7 @@
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;
}