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KVM: MMU: Make cmpxchg_gpte aware of nesting too 

This patch makes the cmpxchg_gpte() function aware of the
difference between l1-gfns and l2-gfns when nested
virtualization is in use.  This fixes a potential
data-corruption problem in the l1-guest and makes the code
work correct (at least as correct as the hardware which is
emulated in this code) again.

Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Roedel, Joerg 2011-04-20 15:33:16 +02:00 committed by Avi Kivity
parent 13db70eca6
commit a78484c60e
1 changed files with 23 additions and 7 deletions
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30
arch/x86/kvm/paging_tmpl.h
View File

@ -78,15 +78,21 @@ static gfn_t gpte_to_gfn_lvl(pt_element_t gpte, int lvl)
return (gpte & PT_LVL_ADDR_MASK(lvl)) >> PAGE_SHIFT; return (gpte & PT_LVL_ADDR_MASK(lvl)) >> PAGE_SHIFT;
} }
static bool FNAME(cmpxchg_gpte)(struct kvm *kvm, static int FNAME(cmpxchg_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
gfn_t table_gfn, unsigned index, gfn_t table_gfn, unsigned index,
pt_element_t orig_pte, pt_element_t new_pte) pt_element_t orig_pte, pt_element_t new_pte)
{ {
pt_element_t ret; pt_element_t ret;
pt_element_t *table; pt_element_t *table;
struct page *page; struct page *page;
gpa_t gpa;
page = gfn_to_page(kvm, table_gfn); gpa = mmu->translate_gpa(vcpu, table_gfn << PAGE_SHIFT,
PFERR_USER_MASK|PFERR_WRITE_MASK);
if (gpa == UNMAPPED_GVA)
return -EFAULT;
page = gfn_to_page(vcpu->kvm, gpa_to_gfn(gpa));
table = kmap_atomic(page, KM_USER0); table = kmap_atomic(page, KM_USER0);
ret = CMPXCHG(&table[index], orig_pte, new_pte); ret = CMPXCHG(&table[index], orig_pte, new_pte);
@ -192,11 +198,17 @@ walk:
#endif #endif
if (!eperm && !rsvd_fault && !(pte & PT_ACCESSED_MASK)) { if (!eperm && !rsvd_fault && !(pte & PT_ACCESSED_MASK)) {
int ret;
trace_kvm_mmu_set_accessed_bit(table_gfn, index, trace_kvm_mmu_set_accessed_bit(table_gfn, index,
sizeof(pte)); sizeof(pte));
if (FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn, ret = FNAME(cmpxchg_gpte)(vcpu, mmu, table_gfn,
index, pte, pte|PT_ACCESSED_MASK)) index, pte, pte|PT_ACCESSED_MASK);
if (ret < 0) {
present = false;
break;
} else if (ret)
goto walk; goto walk;
mark_page_dirty(vcpu->kvm, table_gfn); mark_page_dirty(vcpu->kvm, table_gfn);
pte |= PT_ACCESSED_MASK; pte |= PT_ACCESSED_MASK;
} }
@ -245,13 +257,17 @@ walk:
goto error; goto error;
if (write_fault && !is_dirty_gpte(pte)) { if (write_fault && !is_dirty_gpte(pte)) {
bool ret; int ret;
trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte)); trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte));
ret = FNAME(cmpxchg_gpte)(vcpu->kvm, table_gfn, index, pte, ret = FNAME(cmpxchg_gpte)(vcpu, mmu, table_gfn, index, pte,
pte|PT_DIRTY_MASK); pte|PT_DIRTY_MASK);
if (ret) if (ret < 0) {
present = false;
goto error;
} else if (ret)
goto walk; goto walk;
mark_page_dirty(vcpu->kvm, table_gfn); mark_page_dirty(vcpu->kvm, table_gfn);
pte |= PT_DIRTY_MASK; pte |= PT_DIRTY_MASK;
walker->ptes[walker->level - 1] = pte; walker->ptes[walker->level - 1] = pte;