Re: [PATCH] KVM: SVM: Analyze is_guest_mode() in svm_vcpu_run()

[Krish Sadhukhan]

On 9/13/20 11:55 PM, Wanpeng Li wrote:
From: Wanpeng Li <wanpen...@tencent.com>

Analyze is_guest_mode() in svm_vcpu_run() instead of 
svm_exit_handlers_fastpath()
in conformity with VMX version.

Suggested-by: Vitaly Kuznetsov <vkuzn...@redhat.com>
Signed-off-by: Wanpeng Li <wanpen...@tencent.com>
---
  arch/x86/kvm/svm/svm.c | 7 +++++--
  1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 3da5b2f..009035a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3393,8 +3393,7 @@ static void svm_cancel_injection(struct kvm_vcpu *vcpu)
  
  static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
  {
-       if (!is_guest_mode(vcpu) &&
-           to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
+       if (to_svm(vcpu)->vmcb->control.exit_code == SVM_EXIT_MSR &&
            to_svm(vcpu)->vmcb->control.exit_info_1)
                return handle_fastpath_set_msr_irqoff(vcpu);
  
@@ -3580,6 +3579,10 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu *vcpu)
                svm_handle_mce(svm);
  
  	svm_complete_interrupts(svm);
+
+       if (is_guest_mode(vcpu))
+               return EXIT_FASTPATH_NONE;
+
        exit_fastpath = svm_exit_handlers_fastpath(vcpu);
        return exit_fastpath;

Not related to your changes, but should we get rid of the variable 
'exit_fastpath' and just do,

        return svm_exit_handler_fastpath(vcpu);

It seems the variable isn't used anywhere else and svm_vcpu_run() 
doesn't return from anywhere else either.

Also, svm_exit_handlers_fastpath() doesn't have any other caller.  
Should we get rid of it as well ?


For your changes,

    Reviewed-by: Krish Sadhukhan <krish.sadhuk...@oracle.com>

  }