The cache flush was originally introduced to enforce the cache coherency across VM boundary in SEV, so the flush is not needed in some cases when the page remains in the same VM. wbinvd_on_all_cpus() is a costly operation so use the mmu notifier event type information in the range struct to only do cache flush when needed. The physical page might be allocated to a different VM after the range is unmapped, cleared, released or migrated. So do a cache flush only on those events. Signed-off-by: Jacky Li <jackyli@xxxxxxxxxx> Signed-off-by: Mingwei Zhang <mizhang@xxxxxxxxxx> Suggested-by: Sean Christpherson <seanjc@xxxxxxxxxx> --- arch/x86/kvm/svm/sev.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 8d30f6c5e872..477df8a06629 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2335,7 +2335,11 @@ void sev_guest_memory_reclaimed(struct kvm *kvm, if (!sev_guest(kvm)) return; - wbinvd_on_all_cpus(); + if (mmu_notifier_event == MMU_NOTIFY_UNMAP || + mmu_notifier_event == MMU_NOTIFY_CLEAR || + mmu_notifier_event == MMU_NOTIFY_RELEASE || + mmu_notifier_event == MMU_NOTIFY_MIGRATE) + wbinvd_on_all_cpus(); } void sev_free_vcpu(struct kvm_vcpu *vcpu) -- 2.43.0.rc0.421.g78406f8d94-goog
