KVM: x86: Re-enter guest if WRMSR(X2APIC_ICR) fastpath is successful

sean-jc · sean-jc · commit 0dd45f2cd8cc · 2024-08-29T19:50:21.000-07:00
Re-enter the guest in the fastpath if WRMSR emulation for x2APIC's ICR is successful, as no additional work is needed, i.e. there is no code unique for WRMSR exits between the fastpath and the "!= EXIT_FASTPATH_NONE" check in __vmx_handle_exit(). Link: https://lore.kernel.org/r/20240802195120.325560-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
@@ -2195,7 +2195,7 @@ fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu)
 		data = kvm_read_edx_eax(vcpu);
 		if (!handle_fastpath_set_x2apic_icr_irqoff(vcpu, data)) {
 			kvm_skip_emulated_instruction(vcpu);
-			ret = EXIT_FASTPATH_EXIT_HANDLED;
+			ret = EXIT_FASTPATH_REENTER_GUEST;
 		}
 		break;
 	case MSR_IA32_TSC_DEADLINE:

Original file line number	Diff line number	Diff line change
`@@ -2195,7 +2195,7 @@ fastpath_t handle_fastpath_set_msr_irqoff(struct kvm_vcpu *vcpu)`
`2195`	`2195`	`data = kvm_read_edx_eax(vcpu);`
`2196`	`2196`	`if (!handle_fastpath_set_x2apic_icr_irqoff(vcpu, data)) {`
`2197`	`2197`	`kvm_skip_emulated_instruction(vcpu);`
`2198`		`- ret = EXIT_FASTPATH_EXIT_HANDLED;`
	`2198`	`+ ret = EXIT_FASTPATH_REENTER_GUEST;`
`2199`	`2199`	`}`
`2200`	`2200`	`break;`
`2201`	`2201`	`case MSR_IA32_TSC_DEADLINE:`