To reduce the contentions caused by MMU lock, some MMU operations can
be performed under read lock.
One improvement is to add a fast path for permission relaxation during
dirty logging under the read lock.
Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 2 ++
arch/arm64/kvm/mmu.c | 36 +++++++++++++++----------------
2 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 3b44ea17af88..6c99c0335bae 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -50,6 +50,8 @@
#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \
KVM_DIRTY_LOG_INITIALLY_SET)
+#define KVM_HAVE_MMU_RWLOCK
+
/*
* Mode of operation configurable with kvm-arm.mode early param.
* See Documentation/admin-guide/kernel-parameters.txt for more information.
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index bc2aba953299..cafd5813c949 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -58,7 +58,7 @@ static int stage2_apply_range(struct kvm *kvm, phys_addr_t addr,
break;
if (resched && next != end)
- cond_resched_lock(&kvm->mmu_lock);
+ cond_resched_rwlock_write(&kvm->mmu_lock);
} while (addr = next, addr != end);
return ret;
@@ -179,7 +179,7 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
phys_addr_t end = start + size;
- assert_spin_locked(&kvm->mmu_lock);
+ lockdep_assert_held_write(&kvm->mmu_lock);
WARN_ON(size & ~PAGE_MASK);
WARN_ON(stage2_apply_range(kvm, start, end, kvm_pgtable_stage2_unmap,
may_block));
@@ -213,13 +213,13 @@ static void stage2_flush_vm(struct kvm *kvm)
int idx, bkt;
idx = srcu_read_lock(&kvm->srcu);
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
slots = kvm_memslots(kvm);
kvm_for_each_memslot(memslot, bkt, slots)
stage2_flush_memslot(kvm, memslot);
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);
}
@@ -720,13 +720,13 @@ void stage2_unmap_vm(struct kvm *kvm)
idx = srcu_read_lock(&kvm->srcu);
mmap_read_lock(current->mm);
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
slots = kvm_memslots(kvm);
kvm_for_each_memslot(memslot, bkt, slots)
stage2_unmap_memslot(kvm, memslot);
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
mmap_read_unlock(current->mm);
srcu_read_unlock(&kvm->srcu, idx);
}
@@ -736,14 +736,14 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
struct kvm *kvm = kvm_s2_mmu_to_kvm(mmu);
struct kvm_pgtable *pgt = NULL;
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
pgt = mmu->pgt;
if (pgt) {
mmu->pgd_phys = 0;
mmu->pgt = NULL;
free_percpu(mmu->last_vcpu_ran);
}
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
if (pgt) {
kvm_pgtable_stage2_destroy(pgt);
@@ -783,10 +783,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
if (ret)
break;
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
ret = kvm_pgtable_stage2_map(pgt, addr, PAGE_SIZE, pa, prot,
&cache);
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
if (ret)
break;
@@ -834,9 +834,9 @@ static void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
start = memslot->base_gfn << PAGE_SHIFT;
end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
stage2_wp_range(&kvm->arch.mmu, start, end);
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
kvm_flush_remote_tlbs(kvm);
}
@@ -1212,7 +1212,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (exec_fault && device)
return -ENOEXEC;
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
pgt = vcpu->arch.hw_mmu->pgt;
if (mmu_notifier_retry(kvm, mmu_seq))
goto out_unlock;
@@ -1271,7 +1271,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
}
out_unlock:
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
kvm_set_pfn_accessed(pfn);
kvm_release_pfn_clean(pfn);
return ret != -EAGAIN ? ret : 0;
@@ -1286,10 +1286,10 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
trace_kvm_access_fault(fault_ipa);
- spin_lock(&vcpu->kvm->mmu_lock);
+ write_lock(&vcpu->kvm->mmu_lock);
mmu = vcpu->arch.hw_mmu;
kpte = kvm_pgtable_stage2_mkyoung(mmu->pgt, fault_ipa);
- spin_unlock(&vcpu->kvm->mmu_lock);
+ write_unlock(&vcpu->kvm->mmu_lock);
pte = __pte(kpte);
if (pte_valid(pte))
@@ -1692,9 +1692,9 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
gpa_t gpa = slot->base_gfn << PAGE_SHIFT;
phys_addr_t size = slot->npages << PAGE_SHIFT;
- spin_lock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
unmap_stage2_range(&kvm->arch.mmu, gpa, size);
- spin_unlock(&kvm->mmu_lock);
+ write_unlock(&kvm->mmu_lock);
}
/*
--
2.34.1.575.g55b058a8bb-goog
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