To reduce MMU lock contention during dirty logging, all permission
relaxation operations would be performed under read lock.
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
arch/arm64/kvm/mmu.c | 50 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index cafd5813c949..dd1f43fba4b0 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1063,6 +1063,54 @@ static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,
return 0;
}
+static bool fast_mark_writable(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
+ struct kvm_memory_slot *memslot, unsigned long fault_status)
+{
+ int ret;
+ bool writable;
+ bool write_fault = kvm_is_write_fault(vcpu);
+ gfn_t gfn = fault_ipa >> PAGE_SHIFT;
+ kvm_pfn_t pfn;
+ struct kvm *kvm = vcpu->kvm;
+ bool logging_active = memslot_is_logging(memslot);
+ unsigned long fault_level = kvm_vcpu_trap_get_fault_level(vcpu);
+ unsigned long fault_granule;
+
+ fault_granule = 1UL << ARM64_HW_PGTABLE_LEVEL_SHIFT(fault_level);
+
+ /* Make sure the fault can be handled in the fast path.
+ * Only handle write permission fault on non-hugepage during dirty
+ * logging period.
+ */
+ if (fault_status != FSC_PERM || fault_granule != PAGE_SIZE
+ || !logging_active || !write_fault)
+ return false;
+
+
+ /* Pin the pfn to make sure it couldn't be freed and be resued for
+ * another gfn.
+ */
+ pfn = __gfn_to_pfn_memslot(memslot, gfn, true, NULL,
+ write_fault, &writable, NULL);
+ if (is_error_pfn(pfn) || !writable)
+ return false;
+
+ read_lock(&kvm->mmu_lock);
+ ret = kvm_pgtable_stage2_relax_perms(
+ vcpu->arch.hw_mmu->pgt, fault_ipa, PAGE_HYP);
+
+ if (!ret) {
+ kvm_set_pfn_dirty(pfn);
+ mark_page_dirty_in_slot(kvm, memslot, gfn);
+ }
+ read_unlock(&kvm->mmu_lock);
+
+ kvm_set_pfn_accessed(pfn);
+ kvm_release_pfn_clean(pfn);
+
+ return true;
+}
+
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
struct kvm_memory_slot *memslot, unsigned long hva,
unsigned long fault_status)
@@ -1085,6 +1133,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R;
struct kvm_pgtable *pgt;
+ if (fast_mark_writable(vcpu, fault_ipa, memslot, fault_status))
+ return 0;
fault_granule = 1UL << ARM64_HW_PGTABLE_LEVEL_SHIFT(fault_level);
write_fault = kvm_is_write_fault(vcpu);
exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu);
--
2.34.1.575.g55b058a8bb-goog
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