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Message-Id: <20221129191946.1735662-4-oliver.upton@linux.dev>
Date: Tue, 29 Nov 2022 19:19:45 +0000
From: Oliver Upton <oliver.upton@...ux.dev>
To: Marc Zyngier <maz@...nel.org>, James Morse <james.morse@....com>,
Alexandru Elisei <alexandru.elisei@....com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Oliver Upton <oliver.upton@...ux.dev>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
kvm@...r.kernel.org, kvmarm@...ts.linux.dev,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/4] KVM: arm64: Handle access faults behind the read lock
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@...ux.dev>
---
arch/arm64/kvm/hyp/pgtable.c | 2 +-
arch/arm64/kvm/mmu.c | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 9626f615d9b8..1a3dd9774707 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -1097,7 +1097,7 @@ kvm_pte_t kvm_pgtable_stage2_mkyoung(struct kvm_pgtable *pgt, u64 addr)
int ret;
ret = stage2_update_leaf_attrs(pgt, addr, 1, KVM_PTE_LEAF_ATTR_LO_S2_AF, 0,
- &pte, NULL, 0);
+ &pte, NULL, KVM_PGTABLE_WALK_SHARED);
if (!ret)
dsb(ishst);
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 886ad5ee767a..347985a56414 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1404,10 +1404,10 @@ 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));
--
2.38.1.584.g0f3c55d4c2-goog
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