Hi Jing,
On Tue, Jan 18, 2022 at 1:57 AM Jing Zhang <jingzhangos@xxxxxxxxxx> wrote:
>
> Replace MMU spinlock with rwlock and update all instances of the lock
> being acquired with a write lock acquisition.
> Future commit will add a fast path for permission relaxation during
> dirty logging under a read lock.
Looking at the code, building it and running it, it seems that all
instances of the lock are covered.
Tested-by: Fuad Tabba <tabba@xxxxxxxxxx>
Reviewed-by: Fuad Tabba <tabba@xxxxxxxxxx>
Thanks,
/fuad
> 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);
> }
>
> /*
> --
> 2.34.1.703.g22d0c6ccf7-goog
>
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> kvmarm@xxxxxxxxxxxxxxxxxxxxx
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