* [PATCH] KVM: x86/mmu: Check for host MMIO exclusion from mem encrypt iff necessary
@ 2022-04-15 0:49 Sean Christopherson
2022-04-20 12:16 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Sean Christopherson @ 2022-04-15 0:49 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li, Jim Mattson,
Joerg Roedel, kvm, linux-kernel
When determining whether or not a SPTE needs to have SME/SEV's memory
encryption flag set, do the moderately expension 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 <seanjc@google.com>
---
arch/x86/kvm/mmu/spte.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 4739b53c9734..aab78574e03d 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;
base-commit: 150866cd0ec871c765181d145aa0912628289c8a
--
2.36.0.rc0.470.gd361397f0d-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: x86/mmu: Check for host MMIO exclusion from mem encrypt iff necessary
2022-04-15 0:49 [PATCH] KVM: x86/mmu: Check for host MMIO exclusion from mem encrypt iff necessary Sean Christopherson
@ 2022-04-20 12:16 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2022-04-20 12:16 UTC (permalink / raw)
To: Sean Christopherson
Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm,
linux-kernel
Queued, thanks.
Paolo
^ permalink raw reply [flat|nested] 2+ messages in thread
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