Mark zapped root pagetables as invalid and ignore such pages during lookup.
This is a problem with the cr3-target feature, where a zapped root table fools
the faulting code into creating a read-only mapping. The result is a lockup
if the instruction can't be emulated.
Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]>
Cc: Anthony Liguori <[EMAIL PROTECTED]>
Index: kvm.paravirt/arch/x86/kvm/mmu.c
===================================================================
--- kvm.paravirt.orig/arch/x86/kvm/mmu.c
+++ kvm.paravirt/arch/x86/kvm/mmu.c
@@ -668,7 +668,8 @@ static struct kvm_mmu_page *kvm_mmu_look
index = kvm_page_table_hashfn(gfn);
bucket = &kvm->arch.mmu_page_hash[index];
hlist_for_each_entry(sp, node, bucket, hash_link)
- if (sp->gfn == gfn && !sp->role.metaphysical) {
+ if (sp->gfn == gfn && !sp->role.metaphysical
+ && !sp->role.invalid) {
pgprintk("%s: found role %x\n",
__FUNCTION__, sp->role.word);
return sp;
@@ -796,8 +797,10 @@ static void kvm_mmu_zap_page(struct kvm
if (!sp->root_count) {
hlist_del(&sp->hash_link);
kvm_mmu_free_page(kvm, sp);
- } else
+ } else {
list_move(&sp->link, &kvm->arch.active_mmu_pages);
+ sp->role.invalid = 1;
+ }
kvm_mmu_reset_last_pte_updated(kvm);
}
Index: kvm.paravirt/include/asm-x86/kvm_host.h
===================================================================
--- kvm.paravirt.orig/include/asm-x86/kvm_host.h
+++ kvm.paravirt/include/asm-x86/kvm_host.h
@@ -140,6 +140,7 @@ union kvm_mmu_page_role {
unsigned pad_for_nice_hex_output : 6;
unsigned metaphysical : 1;
unsigned access : 3;
+ unsigned invalid : 1;
};
};
--
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