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>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b4973f4dab98..4ceefa9567ed 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -444,6 +444,9 @@ struct kvm_vcpu_arch {
 
         cpumask_var_t wbinvd_dirty_mask;
 
+        unsigned long last_retry_eip;
+        unsigned long last_retry_addr;
+
         struct {
                 bool halted;
                 gfn_t gfns[roundup_pow_of_two(ASYNC_PF_PER_VCPU)];
@@ -692,6 +695,7 @@ enum emulation_result {
 #define EMULTYPE_NO_DECODE          (1 << 0)
 #define EMULTYPE_TRAP_UD            (1 << 1)
 #define EMULTYPE_SKIP               (1 << 2)
+#define EMULTYPE_RETRY              (1 << 3)
 int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
                             int emulation_type, void *insn, int insn_len);
 
@@ -756,6 +760,7 @@ void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu);
 void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
                        const u8 *new, int bytes,
                        bool guest_initiated);
+int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn);
 int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva);
 void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu);
 int kvm_mmu_load(struct kvm_vcpu *vcpu);