From: Sean Christopherson Date: Fri, 15 Apr 2022 00:49:09 +0000 (+0000) Subject: KVM: x86/mmu: Check for host MMIO exclusion from mem encrypt iff necessary X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=65936229d35883a1637730e628c3c84d3600025d;p=linux.git KVM: x86/mmu: Check for host MMIO exclusion from mem encrypt iff necessary When determining whether or not a SPTE needs to have SME/SEV's memory encryption flag set, do the moderately expensive host MMIO pfn check if and only if the memory encryption mask is non-zero. Note, KVM could further optimize the host MMIO checks by making a single call to kvm_is_mmio_pfn(), but the tdp_enabled path (for EPT's memtype handling) will likely be split out to a separate flow[*]. At that point, a better approach would be to shove the call to kvm_is_mmio_pfn() into VMX code so that AMD+NPT without SME doesn't get hit with an unnecessary lookup. [*] https://lkml.kernel.org/r/20220321224358.1305530-3-bgardon@google.com Signed-off-by: Sean Christopherson Message-Id: <20220415004909.2216670-1-seanjc@google.com> Signed-off-by: Paolo Bonzini --- diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c index 4739b53c9734d..aab78574e03da 100644 --- a/arch/x86/kvm/mmu/spte.c +++ b/arch/x86/kvm/mmu/spte.c @@ -139,7 +139,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, else pte_access &= ~ACC_WRITE_MASK; - if (!kvm_is_mmio_pfn(pfn)) + if (shadow_me_mask && !kvm_is_mmio_pfn(pfn)) spte |= shadow_me_mask; spte |= (u64)pfn << PAGE_SHIFT;