KVM: x86: Invert emulation re-execute behavior to make it opt-in

Re-execution of an instruction after emulation decode failure is
intended to be used only when emulating shadow page accesses.  Invert
the flag to make allowing re-execution opt-in since that behavior is
by far in the minority.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3b220b8..a69ea11 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1238,7 +1238,7 @@ enum emulation_result {
 #define EMULTYPE_TRAP_UD           (1 << 1)
 #define EMULTYPE_SKIP              (1 << 2)
 #define EMULTYPE_RETRY             (1 << 3)
-#define EMULTYPE_NO_REEXECUTE      (1 << 4)
+#define EMULTYPE_ALLOW_REEXECUTE    (1 << 4)
 #define EMULTYPE_NO_UD_ON_FAIL     (1 << 5)
 #define EMULTYPE_VMWARE                    (1 << 6)
 int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
@@ -1247,15 +1247,13 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, unsigned long cr2,
 static inline int emulate_instruction(struct kvm_vcpu *vcpu,
                        int emulation_type)
 {
-       return x86_emulate_instruction(vcpu, 0,
-                       emulation_type | EMULTYPE_NO_REEXECUTE, NULL, 0);
+       return x86_emulate_instruction(vcpu, 0, emulation_type, NULL, 0);
 }
 
 static inline int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
                                                      void *insn, int insn_len)
 {
-       return x86_emulate_instruction(vcpu, 0, EMULTYPE_NO_REEXECUTE,
-                                      insn, insn_len);
+       return x86_emulate_instruction(vcpu, 0, 0, insn, insn_len);
 }
 
 void kvm_enable_efer_bits(u64);

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a282321..4508c34 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5217,7 +5217,7 @@ static int make_mmu_pages_available(struct kvm_vcpu *vcpu)
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u64 error_code,
                       void *insn, int insn_len)
 {
-       int r, emulation_type = EMULTYPE_RETRY;
+       int r, emulation_type = EMULTYPE_RETRY | EMULTYPE_ALLOW_REEXECUTE;
        enum emulation_result er;
        bool direct = vcpu->arch.mmu.direct_map;
 

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 506bd2b..d6f85ea 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5870,7 +5870,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gva_t cr2,
        gpa_t gpa = cr2;
        kvm_pfn_t pfn;
 
-       if (emulation_type & EMULTYPE_NO_REEXECUTE)
+       if (!(emulation_type & EMULTYPE_ALLOW_REEXECUTE))
                return false;
 
        if (!vcpu->arch.mmu.direct_map) {