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KVM: MMU: Fix SMEP failure during fetch 

This patch fix kvm-unit-tests hanging and incorrect PT_ACCESSED_MASK
bit set in the case of SMEP fault.  The code updated 'eperm' after
the variable was checked.

Signed-off-by: Yang, Wei <wei.y.yang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Yang, Wei Y 2011-08-09 18:14:01 +08:00 committed by Avi Kivity
parent e4e517b4be
commit cd46868c7f
1 changed files with 13 additions and 9 deletions
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22
arch/x86/kvm/paging_tmpl.h
View File

@ -147,7 +147,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
gfn_t table_gfn;
unsigned index, pt_access, uninitialized_var(pte_access);
gpa_t pte_gpa;
bool eperm;
bool eperm, last_gpte;
int offset;
const int write_fault = access & PFERR_WRITE_MASK;
const int user_fault = access & PFERR_USER_MASK;
@ -221,6 +221,17 @@ retry_walk:
eperm = true;
#endif
last_gpte = FNAME(is_last_gpte)(walker, vcpu, mmu, pte);
if (last_gpte) {
pte_access = pt_access &
FNAME(gpte_access)(vcpu, pte, true);
/* check if the kernel is fetching from user page */
if (unlikely(pte_access & PT_USER_MASK) &&
kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))
if (fetch_fault && !user_fault)
eperm = true;
}
if (!eperm && unlikely(!(pte & PT_ACCESSED_MASK))) {
int ret;
trace_kvm_mmu_set_accessed_bit(table_gfn, index,
@ -238,18 +249,12 @@ retry_walk:
walker->ptes[walker->level - 1] = pte;
if (FNAME(is_last_gpte)(walker, vcpu, mmu, pte)) {
if (last_gpte) {
int lvl = walker->level;
gpa_t real_gpa;
gfn_t gfn;
u32 ac;
/* check if the kernel is fetching from user page */
if (unlikely(pte_access & PT_USER_MASK) &&
kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))
if (fetch_fault && !user_fault)
eperm = true;
gfn = gpte_to_gfn_lvl(pte, lvl);
gfn += (addr & PT_LVL_OFFSET_MASK(lvl)) >> PAGE_SHIFT;
@ -295,7 +300,6 @@ retry_walk:
walker->ptes[walker->level - 1] = pte;
}
pte_access = pt_access & FNAME(gpte_access)(vcpu, pte, true);
walker->pt_access = pt_access;
walker->pte_access = pte_access;
pgprintk("%s: pte %llx pte_access %x pt_access %x\n",