Commit fcc5bf89 authored by Jing Zhang's avatar Jing Zhang Committed by Marc Zyngier
Browse files

KVM: arm64: Use read/write spin lock for MMU protection 



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.

Signed-off-by: default avatarJing Zhang <jingzhangos@google.com>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220118015703.3630552-2-jingzhangos@google.com
parent dfd42fac

arch/arm64/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -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.

arch/arm64/kvm/mmu.c

+18 −18
Original line number Diff line number Diff line
@@ -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);

}



/*