Re: [PATCH RESEND 3/3] KVM: SVM: Reenable handle_fastpath_set_msr_irqoff() after complete_interrupts()

[Sean Christopherson]

On Sat, Sep 12, 2020 at 08:15:46AM +0200, Paolo Bonzini wrote:
> The overall patch is fairly simple:
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 03dd7bac8034..d6ce75e107c0 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2938,8 +2938,6 @@ static int handle_exit(struct kvm_vcpu *vcpu,
> fastpath_t exit_fastpath)
>   if (npt_enabled)
>   vcpu->arch.cr3 = svm->vmcb->save.cr3;
> 
> - svm_complete_interrupts(svm);
> -
>   if (is_guest_mode(vcpu)) {
>   int vmexit;
> 
> @@ -3504,7 +3502,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
> kvm_vcpu *vcpu)
>   stgi();
> 
>   /* Any pending NMI will happen here */
> - exit_fastpath = svm_exit_handlers_fastpath(vcpu);
> 
>   if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
>   kvm_after_interrupt(>vcpu);
> @@ -3537,6 +3534,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
> kvm_vcpu *vcpu)
>SVM_EXIT_EXCP_BASE + MC_VECTOR))
>   svm_handle_mce(svm);
> 
> + svm_complete_interrupts(svm);
> + exit_fastpath = svm_exit_handlers_fastpath(vcpu);
> +
>   vmcb_mark_all_clean(svm->vmcb);
>   return exit_fastpath;
>  }
> 
> so I will just squash everything.

The thought behind the multi-patch series was to allow automatically applying
the fix to the 5.8 stable tree without having to take on the risk of moving
svm_complete_interrupts().

Re: [PATCH RESEND 3/3] KVM: SVM: Reenable handle_fastpath_set_msr_irqoff() after complete_interrupts()

[Paolo Bonzini]

The overall patch is fairly simple:

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 03dd7bac8034..d6ce75e107c0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2938,8 +2938,6 @@ static int handle_exit(struct kvm_vcpu *vcpu,
fastpath_t exit_fastpath)
if (npt_enabled)
vcpu->arch.cr3 = svm->vmcb->save.cr3;

-   svm_complete_interrupts(svm);
-
if (is_guest_mode(vcpu)) {
int vmexit;

@@ -3504,7 +3502,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
kvm_vcpu *vcpu)
stgi();

/* Any pending NMI will happen here */
-   exit_fastpath = svm_exit_handlers_fastpath(vcpu);

if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
kvm_after_interrupt(>vcpu);
@@ -3537,6 +3534,9 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct
kvm_vcpu *vcpu)
 SVM_EXIT_EXCP_BASE + MC_VECTOR))
svm_handle_mce(svm);

+   svm_complete_interrupts(svm);
+   exit_fastpath = svm_exit_handlers_fastpath(vcpu);
+
vmcb_mark_all_clean(svm->vmcb);
return exit_fastpath;
 }

so I will just squash everything.

Paolo

[PATCH RESEND 3/3] KVM: SVM: Reenable handle_fastpath_set_msr_irqoff() after complete_interrupts()

[Wanpeng Li]

From: Wanpeng Li 

Moving the call to svm_exit_handlers_fastpath() after svm_complete_interrupts() 
since svm_complete_interrupts() consumes rip and reenable the function 
handle_fastpath_set_msr_irqoff() call in svm_exit_handlers_fastpath().

Suggested-by: Sean Christopherson 
Cc: Paul K. 
Signed-off-by: Wanpeng Li 
---
 arch/x86/kvm/svm/svm.c | 7 ++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 74bcf0a..ac819f0 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3347,6 +3347,11 @@ 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 &&
+   to_svm(vcpu)->vmcb->control.exit_info_1)
+   return handle_fastpath_set_msr_irqoff(vcpu);
+
return EXIT_FASTPATH_NONE;
 }
 
@@ -3495,7 +3500,6 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu 
*vcpu)
stgi();
 
/* Any pending NMI will happen here */
-   exit_fastpath = svm_exit_handlers_fastpath(vcpu);
 
if (unlikely(svm->vmcb->control.exit_code == SVM_EXIT_NMI))
kvm_after_interrupt(>vcpu);
@@ -3529,6 +3533,7 @@ static __no_kcsan fastpath_t svm_vcpu_run(struct kvm_vcpu 
*vcpu)
svm_handle_mce(svm);
 
svm_complete_interrupts(svm);
+   exit_fastpath = svm_exit_handlers_fastpath(vcpu);
 
vmcb_mark_all_clean(svm->vmcb);
return exit_fastpath;
-- 
2.7.4