From: Avi Kivity <a...@redhat.com>
Move the code to check whether a gpte has changed since we fetched it into
a helper.
Signed-off-by: Avi Kivity <a...@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 893a75c..22159e6 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -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]))
@@ -364,17 +373,17 @@ 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);
}
--
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