From: Ashish Kalra Date: Wed, 1 May 2024 08:52:06 +0000 (-0500) Subject: KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP X-Git-Tag: block-6.11-20240726~19^2~4^2~7 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=ea262f8a7c360e71f3cb6c2151fd9bfcefd090e9;p=linux-block.git KVM: SEV: Avoid WBINVD for HVA-based MMU notifications for SNP 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 Reviewed-by: Paolo Bonzini [mdr: Add some clarifications in commit] Signed-off-by: Michael Roth Message-ID: <20240501085210.2213060-17-michael.roth@amd.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 0bbbcadbac72..a876a4186939 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3039,7 +3039,13 @@ do_wbinvd: void sev_guest_memory_reclaimed(struct kvm *kvm) { - if (!sev_guest(kvm)) + /* + * With SNP+gmem, private/encrypted memory is unreachable via the + * hva-based mmu notifiers, so these events are only actually + * pertaining to shared pages where there is no need to perform + * the WBINVD to flush associated caches. + */ + if (!sev_guest(kvm) || sev_snp_guest(kvm)) return; wbinvd_on_all_cpus();