From: David Matlack <dmatlack@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Ben Gardon <bgardon@google.com>,
kvm@vger.kernel.org, David Matlack <dmatlack@google.com>
Subject: [PATCH v2 2/4] KVM: x86/mmu: Clear MMU-writable during changed_pte notifier
Date: Thu, 13 Jan 2022 23:30:18 +0000 [thread overview]
Message-ID: <20220113233020.3986005-3-dmatlack@google.com> (raw)
In-Reply-To: <20220113233020.3986005-1-dmatlack@google.com>
When handling the changed_pte notifier and the new PTE is read-only,
clear both the Host-writable and MMU-writable bits in the SPTE. This
preserves the invariant that MMU-writable is set if-and-only-if
Host-writable is set.
No functional change intended. Nothing currently relies on the
afformentioned invariant and technically the changed_pte notifier is
dead code.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/spte.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 8a7b03207762..f8677404c93c 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -215,6 +215,7 @@ u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn)
new_spte &= ~PT_WRITABLE_MASK;
new_spte &= ~shadow_host_writable_mask;
+ new_spte &= ~shadow_mmu_writable_mask;
new_spte = mark_spte_for_access_track(new_spte);
--
2.34.1.703.g22d0c6ccf7-goog
next prev parent reply other threads:[~2022-01-13 23:30 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 23:30 [PATCH v2 0/4] KVM: x86/mmu: Fix write-protection bug in the TDP MMU David Matlack
2022-01-13 23:30 ` [PATCH v2 1/4] KVM: x86/mmu: Fix write-protection of PTs mapped by " David Matlack
2022-01-14 23:38 ` Sean Christopherson
2022-01-13 23:30 ` David Matlack [this message]
2022-01-14 23:41 ` [PATCH v2 2/4] KVM: x86/mmu: Clear MMU-writable during changed_pte notifier Sean Christopherson
2022-01-13 23:30 ` [PATCH v2 3/4] KVM: x86/mmu: Document and enforce MMU-writable and Host-writable invariants David Matlack
2022-01-14 22:29 ` Sean Christopherson
2022-01-18 17:45 ` David Matlack
2022-01-13 23:30 ` [PATCH v2 4/4] KVM: x86/mmu: Improve TLB flush comment in kvm_mmu_slot_remove_write_access() David Matlack
2022-01-14 23:58 ` Sean Christopherson
2022-01-17 17:59 ` [PATCH v2 0/4] KVM: x86/mmu: Fix write-protection bug in the TDP MMU Paolo Bonzini
2022-01-18 17:38 ` David Matlack
2022-01-18 17:41 ` Paolo Bonzini
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