KVM: x86: retry non-page-table writing instructions
If the emulation is caused by #PF and it is non-page_table writing instruction,
it means the VM-EXIT is caused by shadow page protected, we can zap the shadow
page and retry this instruction directly
The idea is from Avi
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 232c5a3..7a22eb8 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1998,7 +1998,7 @@
kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages;
}
-static int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
+int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct hlist_node *node;
@@ -2007,7 +2007,7 @@
pgprintk("%s: looking for gfn %llx\n", __func__, gfn);
r = 0;
-
+ spin_lock(&kvm->mmu_lock);
for_each_gfn_indirect_valid_sp(kvm, sp, gfn, node) {
pgprintk("%s: gfn %llx role %x\n", __func__, gfn,
sp->role.word);
@@ -2015,8 +2015,11 @@
kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
}
kvm_mmu_commit_zap_page(kvm, &invalid_list);
+ spin_unlock(&kvm->mmu_lock);
+
return r;
}
+EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page);
static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
{
@@ -3698,9 +3701,8 @@
gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL);
- spin_lock(&vcpu->kvm->mmu_lock);
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);
- spin_unlock(&vcpu->kvm->mmu_lock);
+
return r;
}
EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
@@ -3721,10 +3723,18 @@
kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
}
+static bool is_mmio_page_fault(struct kvm_vcpu *vcpu, gva_t addr)
+{
+ if (vcpu->arch.mmu.direct_map || mmu_is_nested(vcpu))
+ return vcpu_match_mmio_gpa(vcpu, addr);
+
+ return vcpu_match_mmio_gva(vcpu, addr);
+}
+
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,
void *insn, int insn_len)
{
- int r;
+ int r, emulation_type = EMULTYPE_RETRY;
enum emulation_result er;
r = vcpu->arch.mmu.page_fault(vcpu, cr2, error_code, false);
@@ -3736,7 +3746,10 @@
goto out;
}
- er = x86_emulate_instruction(vcpu, cr2, 0, insn, insn_len);
+ if (is_mmio_page_fault(vcpu, cr2))
+ emulation_type = 0;
+
+ er = x86_emulate_instruction(vcpu, cr2, emulation_type, insn, insn_len);
switch (er) {
case EMULATE_DONE: