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From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	kvmarm@lists.linux.dev, kvmarm@lists.cs.columbia.edu,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 5/6] KVM: arm64: Handle access faults behind the read lock
Date: Fri,  2 Dec 2022 18:51:55 +0000	[thread overview]
Message-ID: <20221202185156.696189-6-oliver.upton@linux.dev> (raw)
In-Reply-To: <20221202185156.696189-1-oliver.upton@linux.dev>

As the underlying software walkers are able to traverse and update
stage-2 in parallel there is no need to serialize access faults.

Only take the read lock when handling an access fault.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/hyp/pgtable.c | 3 ++-
 arch/arm64/kvm/mmu.c         | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index aa36d896bd8c..30575b5f5dcd 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1120,7 +1120,8 @@ kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 
 	ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
 				       &pte, NULL,
-				       KVM_PGTABLE_WALK_HANDLE_FAULT);
+				       KVM_PGTABLE_WALK_HANDLE_FAULT |
+				       KVM_PGTABLE_WALK_SHARED);
 	if (!ret)
 		dsb(ishst);
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index dd8c715f0775..25e18e1d9a15 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1406,10 +1406,10 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 
 	trace_kvm_access_fault(fault_ipa);
 
-	write_lock(&vcpu->kvm->mmu_lock);
+	read_lock(&vcpu->kvm->mmu_lock);
 	mmu = vcpu->arch.hw_mmu;
 	pte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
-	write_unlock(&vcpu->kvm->mmu_lock);
+	read_unlock(&vcpu->kvm->mmu_lock);
 
 	if (kvm_pte_valid(pte))
 		kvm_set_pfn_accessed(kvm_pte_to_pfn(pte));
-- 
2.39.0.rc0.267.gcb52ba06e7-goog

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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, Ricardo Koller <ricarkol@google.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 5/6] KVM: arm64: Handle access faults behind the read lock
Date: Fri,  2 Dec 2022 18:51:55 +0000	[thread overview]
Message-ID: <20221202185156.696189-6-oliver.upton@linux.dev> (raw)
Message-ID: <20221202185155.pv0u8eAyeXOR4IOcNpwO5AtHmxe0nh91dzQevM2QhOI@z> (raw)
In-Reply-To: <20221202185156.696189-1-oliver.upton@linux.dev>

As the underlying software walkers are able to traverse and update
stage-2 in parallel there is no need to serialize access faults.

Only take the read lock when handling an access fault.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/hyp/pgtable.c | 3 ++-
 arch/arm64/kvm/mmu.c         | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index aa36d896bd8c..30575b5f5dcd 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1120,7 +1120,8 @@ kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 
 	ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
 				       &pte, NULL,
-				       KVM_PGTABLE_WALK_HANDLE_FAULT);
+				       KVM_PGTABLE_WALK_HANDLE_FAULT |
+				       KVM_PGTABLE_WALK_SHARED);
 	if (!ret)
 		dsb(ishst);
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index dd8c715f0775..25e18e1d9a15 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1406,10 +1406,10 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 
 	trace_kvm_access_fault(fault_ipa);
 
-	write_lock(&vcpu->kvm->mmu_lock);
+	read_lock(&vcpu->kvm->mmu_lock);
 	mmu = vcpu->arch.hw_mmu;
 	pte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
-	write_unlock(&vcpu->kvm->mmu_lock);
+	read_unlock(&vcpu->kvm->mmu_lock);
 
 	if (kvm_pte_valid(pte))
 		kvm_set_pfn_accessed(kvm_pte_to_pfn(pte));
-- 
2.39.0.rc0.267.gcb52ba06e7-goog


WARNING: multiple messages have this Message-ID (diff)
From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Oliver Upton <oliver.upton@linux.dev>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	kvmarm@lists.linux.dev, Ricardo Koller <ricarkol@google.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 5/6] KVM: arm64: Handle access faults behind the read lock
Date: Fri,  2 Dec 2022 18:51:55 +0000	[thread overview]
Message-ID: <20221202185156.696189-6-oliver.upton@linux.dev> (raw)
In-Reply-To: <20221202185156.696189-1-oliver.upton@linux.dev>

As the underlying software walkers are able to traverse and update
stage-2 in parallel there is no need to serialize access faults.

Only take the read lock when handling an access fault.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/hyp/pgtable.c | 3 ++-
 arch/arm64/kvm/mmu.c         | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index aa36d896bd8c..30575b5f5dcd 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1120,7 +1120,8 @@ kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
 
 	ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
 				       &pte, NULL,
-				       KVM_PGTABLE_WALK_HANDLE_FAULT);
+				       KVM_PGTABLE_WALK_HANDLE_FAULT |
+				       KVM_PGTABLE_WALK_SHARED);
 	if (!ret)
 		dsb(ishst);
 
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index dd8c715f0775..25e18e1d9a15 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1406,10 +1406,10 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
 
 	trace_kvm_access_fault(fault_ipa);
 
-	write_lock(&vcpu->kvm->mmu_lock);
+	read_lock(&vcpu->kvm->mmu_lock);
 	mmu = vcpu->arch.hw_mmu;
 	pte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
-	write_unlock(&vcpu->kvm->mmu_lock);
+	read_unlock(&vcpu->kvm->mmu_lock);
 
 	if (kvm_pte_valid(pte))
 		kvm_set_pfn_accessed(kvm_pte_to_pfn(pte));
-- 
2.39.0.rc0.267.gcb52ba06e7-goog


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2022-12-02 18:52 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-02 18:51 [PATCH v2 0/6] KVM: arm64: Parallel access faults Oliver Upton
2022-12-02 18:51 ` Oliver Upton
2022-12-02 18:51 ` Oliver Upton
2022-12-02 18:51 ` [PATCH v2 1/6] KVM: arm64: Use KVM's pte type/helpers in handle_access_fault() Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51 ` [PATCH v2 2/6] KVM: arm64: Ignore EAGAIN for walks outside of a fault Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51 ` [PATCH v2 3/6] KVM: arm64: Return EAGAIN for invalid PTE in attr walker Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51 ` [PATCH v2 4/6] KVM: arm64: Don't serialize if the access flag isn't set Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51 ` Oliver Upton [this message]
2022-12-02 18:51   ` [PATCH v2 5/6] KVM: arm64: Handle access faults behind the read lock Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51 ` [PATCH v2 6/6] KVM: arm64: Condition HW AF updates on config option Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2022-12-02 18:51   ` Oliver Upton
2023-01-23 20:29 ` [PATCH v2 0/6] KVM: arm64: Parallel access faults Oliver Upton
2023-01-23 20:29   ` Oliver Upton

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