[RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code

From: Sean Christopherson
Date: Thu Aug 22 2019 - 21:07:50 EST


Immediately inject a #UD and return EMULATE done if emulation fails when
handling an intercepted #UD. This helps pave the way for removing
EMULATE_FAIL altogether.

Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/x86.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a1f9e36b2d58..bff3320aa78e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5328,7 +5328,6 @@ EXPORT_SYMBOL_GPL(kvm_write_guest_virt_system);
int handle_ud(struct kvm_vcpu *vcpu)
{
int emul_type = EMULTYPE_TRAP_UD;
- enum emulation_result er;
char sig[5]; /* ud2; .ascii "kvm" */
struct x86_exception e;

@@ -5340,12 +5339,7 @@ int handle_ud(struct kvm_vcpu *vcpu)
emul_type = EMULTYPE_TRAP_UD_FORCED;
}

- er = kvm_emulate_instruction(vcpu, emul_type);
- if (er == EMULATE_USER_EXIT)
- return 0;
- if (er != EMULATE_DONE)
- kvm_queue_exception(vcpu, UD_VECTOR);
- return 1;
+ return kvm_emulate_instruction(vcpu, emul_type) != EMULATE_USER_EXIT;
}
EXPORT_SYMBOL_GPL(handle_ud);

@@ -6533,8 +6527,10 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
++vcpu->stat.insn_emulation;
if (r != EMULATION_OK) {
if ((emulation_type & EMULTYPE_TRAP_UD) ||
- (emulation_type & EMULTYPE_TRAP_UD_FORCED))
- return EMULATE_FAIL;
+ (emulation_type & EMULTYPE_TRAP_UD_FORCED)) {
+ kvm_queue_exception(vcpu, UD_VECTOR);
+ return EMULATE_DONE;
+ }
if (reexecute_instruction(vcpu, cr2, write_fault_to_spt,
emulation_type))
return EMULATE_DONE;
--
2.22.0