KVM: x86: Factor out x86 instruction emulation with decoding
Move the instruction decode part out of x86_emulate_instruction() for it
to be used in other places. Also kvm_clear_exception_queue() is moved
inside the if-statement as it doesn't apply when KVM are coming back from
userspace.
Co-developed-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Wei Huang <wei.huang2@amd.com>
Message-Id: <20210126081831.570253-2-wei.huang2@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fae4ccb..ae8efb0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7317,6 +7317,42 @@ static bool is_vmware_backdoor_opcode(struct x86_emulate_ctxt *ctxt)
return false;
}
+/*
+ * Decode to be emulated instruction. Return EMULATION_OK if success.
+ */
+int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type,
+ void *insn, int insn_len)
+{
+ int r = EMULATION_OK;
+ struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
+
+ init_emulate_ctxt(vcpu);
+
+ /*
+ * We will reenter on the same instruction since we do not set
+ * complete_userspace_io. This does not handle watchpoints yet,
+ * those would be handled in the emulate_ops.
+ */
+ if (!(emulation_type & EMULTYPE_SKIP) &&
+ kvm_vcpu_check_breakpoint(vcpu, &r))
+ return r;
+
+ ctxt->interruptibility = 0;
+ ctxt->have_exception = false;
+ ctxt->exception.vector = -1;
+ ctxt->perm_ok = false;
+
+ ctxt->ud = emulation_type & EMULTYPE_TRAP_UD;
+
+ r = x86_decode_insn(ctxt, insn, insn_len);
+
+ trace_kvm_emulate_insn_start(vcpu);
+ ++vcpu->stat.insn_emulation;
+
+ return r;
+}
+EXPORT_SYMBOL_GPL(x86_decode_emulated_instruction);
+
int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
int emulation_type, void *insn, int insn_len)
{
@@ -7336,32 +7372,12 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
*/
write_fault_to_spt = vcpu->arch.write_fault_to_shadow_pgtable;
vcpu->arch.write_fault_to_shadow_pgtable = false;
- kvm_clear_exception_queue(vcpu);
if (!(emulation_type & EMULTYPE_NO_DECODE)) {
- init_emulate_ctxt(vcpu);
+ kvm_clear_exception_queue(vcpu);
- /*
- * We will reenter on the same instruction since
- * we do not set complete_userspace_io. This does not
- * handle watchpoints yet, those would be handled in
- * the emulate_ops.
- */
- if (!(emulation_type & EMULTYPE_SKIP) &&
- kvm_vcpu_check_breakpoint(vcpu, &r))
- return r;
-
- ctxt->interruptibility = 0;
- ctxt->have_exception = false;
- ctxt->exception.vector = -1;
- ctxt->perm_ok = false;
-
- ctxt->ud = emulation_type & EMULTYPE_TRAP_UD;
-
- r = x86_decode_insn(ctxt, insn, insn_len);
-
- trace_kvm_emulate_insn_start(vcpu);
- ++vcpu->stat.insn_emulation;
+ r = x86_decode_emulated_instruction(vcpu, emulation_type,
+ insn, insn_len);
if (r != EMULATION_OK) {
if ((emulation_type & EMULTYPE_TRAP_UD) ||
(emulation_type & EMULTYPE_TRAP_UD_FORCED)) {
