Commit fc61f554 authored by Oliver Upton's avatar Oliver Upton
Browse files

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.

Link: https://lore.kernel.org/r/20221202185156.696189-6-oliver.upton@linux.dev


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 7d29a240

arch/arm64/kvm/hyp/pgtable.c

+2 −1
Original line number Diff line number Diff line
@@ -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);

arch/arm64/kvm/mmu.c

+2 −2
Original line number Diff line number Diff line
@@ -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));