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

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Date:   Thu, 22 Aug 2019 18:07:04 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code

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@...el.com>
---
 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