There is not much point in write protecting large mappings. This
can only happen when a page is shadowed during the window between
is_largepage_backed and mmu_lock acquision. Zap the entry instead, so
the next pagefault will find a shadowed page via is_largepage_backed and
fallback to 4k translations.
Simplifies out of sync shadow.
Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>
Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -1180,11 +1180,16 @@ static int set_spte(struct kvm_vcpu *vcp
|| (write_fault && !is_write_protection(vcpu) && !user_fault)) {
struct kvm_mmu_page *shadow;
+ if (largepage && has_wrprotected_page(vcpu->kvm, gfn)) {
+ ret = 1;
+ spte = shadow_trap_nonpresent_pte;
+ goto set_pte;
+ }
+
spte |= PT_WRITABLE_MASK;
shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn);
- if (shadow ||
- (largepage && has_wrprotected_page(vcpu->kvm, gfn))) {
+ if (shadow) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__func__, gfn);
ret = 1;
@@ -1197,6 +1202,7 @@ static int set_spte(struct kvm_vcpu *vcp
if (pte_access & ACC_WRITE_MASK)
mark_page_dirty(vcpu->kvm, gfn);
+set_pte:
set_shadow_pte(shadow_pte, spte);
return ret;
}
--
--
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