[PATCH v2 2/6] KVM: nSVM: Simplify error handling of nested_svm_copy_vmcb12_to_cache()

[Yosry Ahmed <yosry@kernel.org>]

nested_svm_vmrun() currently stores the return value of
nested_svm_copy_vmcb12_to_cache() in a local variable 'err', separate
from the generally used 'ret' variable. This is done to have a single
call to kvm_skip_emulated_instruction(), such that we can store the
return value of kvm_skip_emulated_instruction() in 'ret', and then
re-check the return value of nested_svm_copy_vmcb12_to_cache() in 'err'.

The code is unnecessarily confusing. Instead, call
kvm_skip_emulated_instruction() in the failure path of
nested_svm_copy_vmcb12_to_cache() if the return value is not -EFAULT,
and drop 'err'.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
 arch/x86/kvm/svm/nested.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b191c6cab57db..6d4c053778b21 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1079,7 +1079,7 @@ static int nested_svm_copy_vmcb12_to_cache(struct kvm_vcpu *vcpu, u64 vmcb12_gpa
 int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	int ret, err;
+	int ret;
 	u64 vmcb12_gpa;
 	struct vmcb *vmcb01 = svm->vmcb01.ptr;
 
@@ -1104,19 +1104,20 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 		return -EINVAL;
 
 	vmcb12_gpa = svm->vmcb->save.rax;
-	err = nested_svm_copy_vmcb12_to_cache(vcpu, vmcb12_gpa);
-	if (err == -EFAULT) {
+	ret = nested_svm_copy_vmcb12_to_cache(vcpu, vmcb12_gpa);
+
+	/*
+	 * Advance RIP if #GP or #UD are not injected, but otherwise
+	 * stop if copying and checking vmcb12 failed.
+	 */
+	if (ret == -EFAULT) {
 		kvm_inject_gp(vcpu, 0);
 		return 1;
+	} else if (ret) {
+		return kvm_skip_emulated_instruction(vcpu);
 	}
 
-	/*
-	 * Advance RIP if #GP or #UD are not injected, but otherwise stop if
-	 * copying and checking vmcb12 failed.
-	 */
 	ret = kvm_skip_emulated_instruction(vcpu);
-	if (err)
-		return ret;
 
 	/*
 	 * Since vmcb01 is not in use, we can use it to store some of the L1
-- 
2.53.0.473.g4a7958ca14-goog