[PATCH v7 03/17] KVM: nSVM: Unify RIP and PMU handling calls when emulating VMRUN

[Yosry Ahmed]

The code paths for advancing RIP and retiring the instruction for RIP
are very similar whether or not caching vmcb12 succeeds. The only
difference is handling mapping failures (i.e. EFAULT).

Pull the mapping failure handling out and unify the calls to
svm_skip_emulated_instruction() and kvm_pmu_instruction_retired(), but
return immediately after if copying and caching vmcb12 failed. A nice
side effect of this is that the FIXME comment is now above the only code
path calling svm_skip_emulated_instruction().

Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 20 ++++++++------------
 1 file changed, 8 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index ddf18a6daf823..0063ccbd327bc 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1141,20 +1141,13 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 	}
 
 	ret = nested_svm_copy_vmcb12_to_cache(vcpu, vmcb12_gpa);
-	if (ret) {
-		if (ret == -EFAULT)
-			return kvm_handle_memory_failure(vcpu, X86EMUL_IO_NEEDED, NULL);
-
-		/* Advance RIP past VMRUN as part of the nested #VMEXIT. */
-		if (!svm_skip_emulated_instruction(vcpu))
-			return 0;
-
-		kvm_pmu_instruction_retired(vcpu);
-		return 1;
-	}
+	if (ret == -EFAULT)
+		return kvm_handle_memory_failure(vcpu, X86EMUL_IO_NEEDED, NULL);
 
 	/*
-	 * At this point, VMRUN is guaranteed to not fault; advance RIP.
+	 * At this point, VMRUN is guaranteed to not fault; advance RIP. If
+	 * caching vmcb12 failed for other reasons, return immediately afterward
+	 * as a nested #VMEXIT was already set up.
 	 *
 	 * FIXME: If TF is set on VMRUN should inject a #DB (or handle guest
 	 * debugging) right after #VMEXIT, right now it's just ignored.
@@ -1164,6 +1157,9 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 
 	kvm_pmu_instruction_retired(vcpu);
 
+	if (ret)
+		return 1;
+
 	/*
 	 * Since vmcb01 is not in use, we can use it to store some of the L1
 	 * state.
-- 
2.54.0.794.g4f17f83d09-goog