From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"Yan Zhao" <yan.y.zhao@intel.com>,
"Sagi Shahar" <sagis@google.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
"David Matlack" <dmatlack@google.com>,
"James Houghton" <jthoughton@google.com>
Subject: [PATCH 16/18] KVM: x86/mmu: Set Dirty bit for new SPTEs, even if _hardware_ A/D bits are disabled
Date: Thu, 10 Oct 2024 19:10:48 -0700 [thread overview]
Message-ID: <20241011021051.1557902-17-seanjc@google.com> (raw)
In-Reply-To: <20241011021051.1557902-1-seanjc@google.com>
When making a SPTE, set the Dirty bit in the SPTE as appropriate, even if
hardware A/D bits are disabled. Only EPT allows A/D bits to be disabled,
and for EPT, the bits are software-available (ignored by hardware) when
A/D bits are disabled, i.e. it is perfectly legal for KVM to use the Dirty
to track dirty pages in software.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/spte.c | 2 +-
arch/x86/kvm/mmu/spte.h | 6 ------
2 files changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index 617479efd127..fd8c3c92ade0 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -237,7 +237,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
wrprot = true;
else
spte |= PT_WRITABLE_MASK | shadow_mmu_writable_mask |
- spte_shadow_dirty_mask(spte);
+ shadow_dirty_mask;
}
if (prefetch && !synchronizing)
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index a404279ba731..e90cc401c168 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -316,12 +316,6 @@ static inline bool spte_ad_need_write_protect(u64 spte)
return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED;
}
-static inline u64 spte_shadow_dirty_mask(u64 spte)
-{
- KVM_MMU_WARN_ON(!is_shadow_present_pte(spte));
- return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
-}
-
static inline bool is_access_track_spte(u64 spte)
{
return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
--
2.47.0.rc1.288.g06298d1525-goog
next prev parent reply other threads:[~2024-10-11 2:11 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-11 2:10 [PATCH 00/18] KVM: x86/mmu: A/D cleanups (on top of kvm_follow_pfn) Sean Christopherson
2024-10-11 2:10 ` [PATCH 01/18] KVM: x86/mmu: Flush remote TLBs iff MMU-writable flag is cleared from RO SPTE Sean Christopherson
2024-10-11 2:10 ` [PATCH 02/18] KVM: x86/mmu: Always set SPTE's dirty bit if it's created as writable Sean Christopherson
2024-10-11 2:10 ` [PATCH 03/18] KVM: x86/mmu: Fold all of make_spte()'s writable handling into one if-else Sean Christopherson
2024-10-11 2:10 ` [PATCH 04/18] KVM: x86/mmu: Don't force flush if SPTE update clears Accessed bit Sean Christopherson
2024-10-11 2:10 ` [PATCH 05/18] KVM: x86/mmu: Don't flush TLBs when clearing Dirty bit in shadow MMU Sean Christopherson
2024-10-11 2:10 ` [PATCH 06/18] KVM: x86/mmu: Drop ignored return value from kvm_tdp_mmu_clear_dirty_slot() Sean Christopherson
2024-10-11 2:10 ` [PATCH 07/18] KVM: x86/mmu: Fold mmu_spte_update_no_track() into mmu_spte_update() Sean Christopherson
2024-10-11 2:10 ` [PATCH 08/18] KVM: x86/mmu: WARN and flush if resolving a TDP MMU fault clears MMU-writable Sean Christopherson
2024-10-11 2:10 ` [PATCH 09/18] KVM: x86/mmu: Add a dedicated flag to track if A/D bits are globally enabled Sean Christopherson
2024-10-11 2:10 ` [PATCH 10/18] KVM: x86/mmu: Set shadow_accessed_mask for EPT even if A/D bits disabled Sean Christopherson
2024-10-11 2:10 ` [PATCH 11/18] KVM: x86/mmu: Set shadow_dirty_mask " Sean Christopherson
2024-10-11 2:10 ` [PATCH 12/18] KVM: x86/mmu: Use Accessed bit even when _hardware_ A/D bits are disabled Sean Christopherson
2024-10-11 2:10 ` [PATCH 13/18] KVM: x86/mmu: Process only valid TDP MMU roots when aging a gfn range Sean Christopherson
2024-10-11 2:10 ` [PATCH 14/18] KVM: x86/mmu: Stop processing TDP MMU roots for test_age if young SPTE found Sean Christopherson
2024-10-17 16:52 ` Paolo Bonzini
2024-10-11 2:10 ` [PATCH 15/18] KVM: x86/mmu: Dedup logic for detecting TLB flushes on leaf SPTE changes Sean Christopherson
2024-10-17 16:53 ` Paolo Bonzini
2024-10-11 2:10 ` Sean Christopherson [this message]
2024-10-11 2:10 ` [PATCH 17/18] KVM: Allow arch code to elide TLB flushes when aging a young page Sean Christopherson
2024-10-11 2:10 ` [PATCH 18/18] KVM: x86: Don't emit TLB flushes when aging SPTEs for mmu_notifiers Sean Christopherson
2024-10-17 16:55 ` [PATCH 00/18] KVM: x86/mmu: A/D cleanups (on top of kvm_follow_pfn) Paolo Bonzini
2024-10-31 19:51 ` Sean Christopherson
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