KVM: SVM: Don't set GIF when clearing EFER.SVME

[PATCH] KVM: SVM: Don't set GIF when clearing EFER.SVME

Posted by Jim Mattson 4 months ago

Clearing EFER.SVME is not architected to set GIF. Don't set GIF when
emulating a change to EFER that clears EFER.SVME.

This is covered in the discussion at
https://lore.kernel.org/all/5b8787b8-16e9-13dc-7fca-0dc441d673f9@citrix.com/.

Fixes: c513f484c558 ("KVM: nSVM: leave guest mode when clearing EFER.SVME")
Signed-off-by: Jim Mattson <jmattson@google.com>
---
 arch/x86/kvm/svm/svm.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 3a9fe0a8b78c..5387851a96da 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -223,7 +223,6 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 	if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) {
 		if (!(efer & EFER_SVME)) {
 			svm_leave_nested(vcpu);
-			svm_set_gif(svm, true);
 			/* #GP intercept is still needed for vmware backdoor */
 			if (!enable_vmware_backdoor)
 				clr_exception_intercept(svm, GP_VECTOR);
-- 
2.51.0.710.ga91ca5db03-goog

Re: [PATCH] KVM: SVM: Don't set GIF when clearing EFER.SVME

Posted by Yosry Ahmed 4 months ago

On Tue, Oct 07, 2025 at 03:44:00PM -0700, Jim Mattson wrote:
> Clearing EFER.SVME is not architected to set GIF. Don't set GIF when
> emulating a change to EFER that clears EFER.SVME.
> 
> This is covered in the discussion at
> https://lore.kernel.org/all/5b8787b8-16e9-13dc-7fca-0dc441d673f9@citrix.com/.
> 
> Fixes: c513f484c558 ("KVM: nSVM: leave guest mode when clearing EFER.SVME")
> Signed-off-by: Jim Mattson <jmattson@google.com>

Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>

> ---
>  arch/x86/kvm/svm/svm.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 3a9fe0a8b78c..5387851a96da 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -223,7 +223,6 @@ int svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
>  	if ((old_efer & EFER_SVME) != (efer & EFER_SVME)) {
>  		if (!(efer & EFER_SVME)) {
>  			svm_leave_nested(vcpu);
> -			svm_set_gif(svm, true);
>  			/* #GP intercept is still needed for vmware backdoor */
>  			if (!enable_vmware_backdoor)
>  				clr_exception_intercept(svm, GP_VECTOR);
> -- 
> 2.51.0.710.ga91ca5db03-goog
>