| Message ID | 20240421180122.1650812-18-michael.roth@amd.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Delegated to: | Herbert Xu |
| Headers | show |
| Series | Add AMD Secure Nested Paging (SEV-SNP) Hypervisor Support | expand |
On Sun, Apr 21, 2024, Michael Roth wrote: > From: Ashish Kalra <ashish.kalra@amd.com> > > With SNP/guest_memfd, private/encrypted memory should not be mappable, > and MMU notifications for HVA-mapped memory will only be relevant to > unencrypted guest memory. Therefore, the rationale behind issuing a > wbinvd_on_all_cpus() in sev_guest_memory_reclaimed() should not apply > for SNP guests and can be ignored. > > Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> > [mdr: Add some clarifications in commit] > Signed-off-by: Michael Roth <michael.roth@amd.com> > --- > arch/x86/kvm/svm/sev.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c > index 243369e302f4..cf00a811aca5 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -3042,7 +3042,14 @@ static void sev_flush_encrypted_page(struct kvm_vcpu *vcpu, void *va) > > void sev_guest_memory_reclaimed(struct kvm *kvm) > { > - if (!sev_guest(kvm)) > + /* > + * With SNP+gmem, private/encrypted memory should be Not should, *is*. > + * unreachable via the hva-based mmu notifiers. Additionally, > + * for shared->private translations, H/W coherency will ensure > + * first guest access to the page would clear out any existing > + * dirty copies of that cacheline. I don't see how this second part is relevant. > + */ > + if (!sev_guest(kvm) || sev_snp_guest(kvm)) > return; > > wbinvd_on_all_cpus(); > -- > 2.25.1 >
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 243369e302f4..cf00a811aca5 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3042,7 +3042,14 @@ static void sev_flush_encrypted_page(struct kvm_vcpu *vcpu, void *va) void sev_guest_memory_reclaimed(struct kvm *kvm) { - if (!sev_guest(kvm)) + /* + * With SNP+gmem, private/encrypted memory should be + * unreachable via the hva-based mmu notifiers. Additionally, + * for shared->private translations, H/W coherency will ensure + * first guest access to the page would clear out any existing + * dirty copies of that cacheline. + */ + if (!sev_guest(kvm) || sev_snp_guest(kvm)) return; wbinvd_on_all_cpus();