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KVM: MMU: Add gpte_valid() helper

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Move the code to check whether a gpte has changed since we fetched it into
a helper.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Avi Kivity 2010-07-13 14:27:08 +03:00
parent a357bd229c
commit 39c8c672a1
1 changed files with 17 additions and 8 deletions
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25
arch/x86/kvm/paging_tmpl.h
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@ -299,6 +299,17 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
gpte_to_gfn(gpte), pfn, true, true);
}
static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
struct guest_walker *gw, int level)
{
int r;
pt_element_t curr_pte;
r = kvm_read_guest_atomic(vcpu->kvm, gw->pte_gpa[level - 1],
&curr_pte, sizeof(curr_pte));
return r || curr_pte != gw->ptes[level - 1];
}
/*
* Fetch a shadow pte for a specific level in the paging hierarchy.
*/
@ -312,11 +323,9 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
u64 *sptep = NULL;
int direct;
gfn_t table_gfn;
int r;
int level;
bool dirty = is_dirty_gpte(gw->ptes[gw->level - 1]);
unsigned direct_access;
pt_element_t curr_pte;
struct kvm_shadow_walk_iterator iterator;
if (!is_present_gpte(gw->ptes[gw->level - 1]))
@ -365,17 +374,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
}
sp = kvm_mmu_get_page(vcpu, table_gfn, addr, level-1,
direct, access, sptep);
if (!direct) {
r = kvm_read_guest_atomic(vcpu->kvm,
gw->pte_gpa[level - 2],
&curr_pte, sizeof(curr_pte));
if (r || curr_pte != gw->ptes[level - 2]) {
if (!direct)
/*
* Verify that the gpte in the page we've just write
* protected is still there.
*/
if (FNAME(gpte_changed)(vcpu, gw, level - 1)) {
kvm_mmu_put_page(sp, sptep);
kvm_release_pfn_clean(pfn);
sptep = NULL;
break;
}
}
link_shadow_page(sptep, sp);
}