| Message ID | 1dbc14735bbc336c171ef8fefd4aef39ddf95816.1655761627.git.ashish.kalra@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) | expand |
On Mon, Jun 20, 2022 at 5:15 PM Ashish Kalra <Ashish.Kalra@amd.com> wrote: > > From: Michael Roth <michael.roth@amd.com> > > Signed-off-by: Michael Roth <michael.roth@amd.com> Can you add a commit description here? Is this a fix for existing SEV-ES support or should this be incorporated into a patch in this series which adds this issue? > --- > arch/x86/kvm/svm/svm.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index fced6ea423ad..f78e3b1bde0e 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1352,7 +1352,7 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu) > static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) > { > struct vcpu_svm *svm = to_svm(vcpu); > - struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); > + struct svm_cpu_data *sd; > > if (sev_es_guest(vcpu->kvm)) > sev_es_unmap_ghcb(svm); > @@ -1360,6 +1360,10 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) > if (svm->guest_state_loaded) > return; > > + /* sev_es_unmap_ghcb() can resched, so grab per-cpu pointer afterward. */ > + barrier(); > + sd = per_cpu(svm_data, vcpu->cpu); > + > /* > * Save additional host state that will be restored on VMEXIT (sev-es) > * or subsequent vmload of host save area. > -- > 2.25.1 >
[AMD Official Use Only - General] Hello Peter, >> >> From: Michael Roth <michael.roth@amd.com> >> >> Signed-off-by: Michael Roth <michael.roth@amd.com> >Can you add a commit description here? Is this a fix for existing SEV-ES support or should this be incorporated into a patch in this series which adds this issue? This actually fixes issues caused due to preemption happening in svm_prepare_switch_to_guest() when kvm_vcpu_map() is called to map in the GHCB before entering the guest. This is a temporary fix and what we need to do is to prevent getting preempted after vcpu_enter_guest() has disabled preemption, have some ideas about using gfn_to_pfn_cache() infrastructure to re-use the already mapped GHCB at guest exit, so that we can avoid calling kvm_vcpu_map() to re-map the GHCB. Thanks, Ashish > --- > arch/x86/kvm/svm/svm.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index > fced6ea423ad..f78e3b1bde0e 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -1352,7 +1352,7 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu) > static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) { > struct vcpu_svm *svm = to_svm(vcpu); > - struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); > + struct svm_cpu_data *sd; > > if (sev_es_guest(vcpu->kvm)) > sev_es_unmap_ghcb(svm); @@ -1360,6 +1360,10 @@ static > void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) > if (svm->guest_state_loaded) > return; > > + /* sev_es_unmap_ghcb() can resched, so grab per-cpu pointer afterward. */ > + barrier(); > + sd = per_cpu(svm_data, vcpu->cpu); > + > /* > * Save additional host state that will be restored on VMEXIT (sev-es) > * or subsequent vmload of host save area. > -- > 2.25.1 >
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index fced6ea423ad..f78e3b1bde0e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1352,7 +1352,7 @@ static void svm_vcpu_free(struct kvm_vcpu *vcpu) static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); - struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); + struct svm_cpu_data *sd; if (sev_es_guest(vcpu->kvm)) sev_es_unmap_ghcb(svm); @@ -1360,6 +1360,10 @@ static void svm_prepare_switch_to_guest(struct kvm_vcpu *vcpu) if (svm->guest_state_loaded) return; + /* sev_es_unmap_ghcb() can resched, so grab per-cpu pointer afterward. */ + barrier(); + sd = per_cpu(svm_data, vcpu->cpu); + /* * Save additional host state that will be restored on VMEXIT (sev-es) * or subsequent vmload of host save area.