linux-kernel - [PATCH v3 18/31] KVM: MMU: mark page dirty in make

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210924163152.289027-19-pbonzini@redhat.com>
Date:   Fri, 24 Sep 2021 12:31:39 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     dmatlack@...gle.com, seanjc@...gle.com
Subject: [PATCH v3 18/31] KVM: MMU: mark page dirty in make_spte

This simplifies set_spte, which we want to remove, and unifies code
between the shadow MMU and the TDP MMU.  The warning will be added
back later to make_spte as well.

There is a small disadvantage in the TDP MMU; it may unnecessarily mark
a page as dirty twice if two vCPUs end up mapping the same page twice.
However, this is a very small cost for a case that is already rare.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu/mmu.c     |  3 ---
 arch/x86/kvm/mmu/spte.c    |  3 +++
 arch/x86/kvm/mmu/tdp_mmu.c | 21 +--------------------
 3 files changed, 4 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8b6dc276935f..5a757953b98b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2688,9 +2688,6 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 	ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative,
 			can_unsync, host_writable, sp_ad_disabled(sp), &spte);
 
-	if (spte & PT_WRITABLE_MASK)
-		kvm_vcpu_mark_page_dirty(vcpu, gfn);
-
 	if (*sptep == spte)
 		ret |= SET_SPTE_SPURIOUS;
 	else if (mmu_spte_update(sptep, spte))
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index a33c581aabd6..66be9452ded1 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -179,6 +179,9 @@ int make_spte(struct kvm_vcpu *vcpu, unsigned int pte_access, int level,
 		  "spte = 0x%llx, level = %d, rsvd bits = 0x%llx", spte, level,
 		  get_rsvd_bits(&vcpu->arch.mmu->shadow_zero_check, spte, level));
 
+	if (spte & PT_WRITABLE_MASK)
+		kvm_vcpu_mark_page_dirty(vcpu, gfn);
+
 	*new_spte = spte;
 	return ret;
 }
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 3bf85a8c7d15..b41b6f5ea82b 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -542,26 +542,7 @@ static inline bool tdp_mmu_map_set_spte_atomic(struct kvm_vcpu *vcpu,
 					       struct tdp_iter *iter,
 					       u64 new_spte)
 {
-	struct kvm *kvm = vcpu->kvm;
-
-	if (!tdp_mmu_set_spte_atomic_no_dirty_log(kvm, iter, new_spte))
-		return false;
-
-	/*
-	 * Use kvm_vcpu_gfn_to_memslot() instead of going through
-	 * handle_changed_spte_dirty_log() to leverage vcpu->last_used_slot.
-	 */
-	if (is_writable_pte(new_spte)) {
-		struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, iter->gfn);
-
-		if (slot && kvm_slot_dirty_track_enabled(slot)) {
-			/* Enforced by kvm_mmu_hugepage_adjust. */
-			WARN_ON_ONCE(iter->level > PG_LEVEL_4K);
-			mark_page_dirty_in_slot(kvm, slot, iter->gfn);
-		}
-	}
-
-	return true;
+	return tdp_mmu_set_spte_atomic_no_dirty_log(vcpu->kvm, iter, new_spte);
 }
 
 static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm,
-- 
2.27.0