[PATCH 1/5] KVM: Move wiping of the kvm->vcpus array to common code

From: Marc Zyngier <maz@kernel.org>
Date: 2021-11-05 19:23:39
Also in: kvm, kvmarm, linuxppc-dev
Subsystem: arm64 port (aarch64 architecture), kernel virtual machine (kvm), kernel virtual machine for arm64 (kvm/arm64), kernel virtual machine for mips (kvm/mips), kernel virtual machine for powerpc (kvm/powerpc), kernel virtual machine for risc-v (kvm/riscv), kernel virtual machine for x86 (kvm/x86), kernel virtual machine for s390 (kvm/s390), linux for powerpc (32-bit and 64-bit), mips, risc-v architecture, s390 architecture, the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Catalin Marinas, Will Deacon, Paolo Bonzini, Marc Zyngier, Oliver Upton, Huacai Chen, Madhavan Srinivasan, Anup Patel, Sean Christopherson, Christian Borntraeger, Janosch Frank, Claudio Imbrenda, Michael Ellerman, Thomas Bogendoerfer, Paul Walmsley, Palmer Dabbelt, Albert Ou, Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

All architectures have similar loops iterating over the vcpus,
freeing one vcpu at a time, and eventually wiping the reference
off the vcpus array. They are also inconsistently taking
the kvm->lock mutex when wiping the references from the array.

Make this code common, which will simplify further changes.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kvm/arm.c       | 10 +---------
 arch/mips/kvm/mips.c       | 21 +--------------------
 arch/powerpc/kvm/powerpc.c | 10 +---------
 arch/riscv/kvm/vm.c        | 10 +---------
 arch/s390/kvm/kvm-s390.c   | 18 +-----------------
 arch/x86/kvm/x86.c         |  9 +--------
 include/linux/kvm_host.h   |  2 +-
 virt/kvm/kvm_main.c        | 20 ++++++++++++++++++--
 8 files changed, 25 insertions(+), 75 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index f5490afe1ebf..75bb7215da03 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c

@@ -175,19 +175,11 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
  */
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	int i;
-
 	bitmap_free(kvm->arch.pmu_filter);
 
 	kvm_vgic_destroy(kvm);
 
-	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-		if (kvm->vcpus[i]) {
-			kvm_vcpu_destroy(kvm->vcpus[i]);
-			kvm->vcpus[i] = NULL;
-		}
-	}
-	atomic_set(&kvm->online_vcpus, 0);
+	kvm_destroy_vcpus(kvm);
 }
 
 int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 562aa878b266..ceacca74f808 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c

@@ -171,25 +171,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	return 0;
 }
 
-void kvm_mips_free_vcpus(struct kvm *kvm)
-{
-	unsigned int i;
-	struct kvm_vcpu *vcpu;
-
-	kvm_for_each_vcpu(i, vcpu, kvm) {
-		kvm_vcpu_destroy(vcpu);
-	}
-
-	mutex_lock(&kvm->lock);
-
-	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
-		kvm->vcpus[i] = NULL;
-
-	atomic_set(&kvm->online_vcpus, 0);
-
-	mutex_unlock(&kvm->lock);
-}
-
 static void kvm_mips_free_gpa_pt(struct kvm *kvm)
 {
 	/* It should always be safe to remove after flushing the whole range */

@@ -199,7 +180,7 @@ static void kvm_mips_free_gpa_pt(struct kvm *kvm)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	kvm_mips_free_vcpus(kvm);
+	kvm_destroy_vcpus(kvm);
 	kvm_mips_free_gpa_pt(kvm);
 }

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 35e9cccdeef9..492e4a4121cb 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c

@@ -463,9 +463,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	unsigned int i;
-	struct kvm_vcpu *vcpu;
-
 #ifdef CONFIG_KVM_XICS
 	/*
 	 * We call kick_all_cpus_sync() to ensure that all

@@ -476,14 +473,9 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 		kick_all_cpus_sync();
 #endif
 
-	kvm_for_each_vcpu(i, vcpu, kvm)
-		kvm_vcpu_destroy(vcpu);
+	kvm_destroy_vcpus(kvm);
 
 	mutex_lock(&kvm->lock);
-	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
-		kvm->vcpus[i] = NULL;
-
-	atomic_set(&kvm->online_vcpus, 0);
 
 	kvmppc_core_destroy_vm(kvm);

diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
index 26399df15b63..6af6cde295eb 100644
--- a/arch/riscv/kvm/vm.c
+++ b/arch/riscv/kvm/vm.c

@@ -46,15 +46,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
-	int i;
-
-	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
-		if (kvm->vcpus[i]) {
-			kvm_vcpu_destroy(kvm->vcpus[i]);
-			kvm->vcpus[i] = NULL;
-		}
-	}
-	atomic_set(&kvm->online_vcpus, 0);
+	kvm_destroy_vcpus(kvm);
 }
 
 int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index c6257f625929..7af53b8788fa 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c

@@ -2819,27 +2819,11 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
 	free_page((unsigned long)(vcpu->arch.sie_block));
 }
 
-static void kvm_free_vcpus(struct kvm *kvm)
-{
-	unsigned int i;
-	struct kvm_vcpu *vcpu;
-
-	kvm_for_each_vcpu(i, vcpu, kvm)
-		kvm_vcpu_destroy(vcpu);
-
-	mutex_lock(&kvm->lock);
-	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
-		kvm->vcpus[i] = NULL;
-
-	atomic_set(&kvm->online_vcpus, 0);
-	mutex_unlock(&kvm->lock);
-}
-
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
 	u16 rc, rrc;
 
-	kvm_free_vcpus(kvm);
+	kvm_destroy_vcpus(kvm);
 	sca_dispose(kvm);
 	kvm_s390_gisa_destroy(kvm);
 	/*

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c1c4e2b05a63..498a43126615 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c

@@ -11302,15 +11302,8 @@ static void kvm_free_vcpus(struct kvm *kvm)
 		kvm_clear_async_pf_completion_queue(vcpu);
 		kvm_unload_vcpu_mmu(vcpu);
 	}
-	kvm_for_each_vcpu(i, vcpu, kvm)
-		kvm_vcpu_destroy(vcpu);
-
-	mutex_lock(&kvm->lock);
-	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
-		kvm->vcpus[i] = NULL;
 
-	atomic_set(&kvm->online_vcpus, 0);
-	mutex_unlock(&kvm->lock);
+	kvm_destroy_vcpus(kvm);
 }
 
 void kvm_arch_sync_events(struct kvm *kvm)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 60a35d9fe259..36967291b8c6 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h

@@ -725,7 +725,7 @@ static inline struct kvm_vcpu *kvm_get_vcpu_by_id(struct kvm *kvm, int id)
 		if (WARN_ON_ONCE(!memslot->npages)) {			\
 		} else
 
-void kvm_vcpu_destroy(struct kvm_vcpu *vcpu);
+void kvm_destroy_vcpus(struct kvm *kvm);
 
 void vcpu_load(struct kvm_vcpu *vcpu);
 void vcpu_put(struct kvm_vcpu *vcpu);

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3f6d450355f0..d83553eeea21 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c

@@ -435,7 +435,7 @@ static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
 	vcpu->last_used_slot = 0;
 }
 
-void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
+static void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
 {
 	kvm_dirty_ring_free(&vcpu->dirty_ring);
 	kvm_arch_vcpu_destroy(vcpu);

@@ -450,7 +450,23 @@ void kvm_vcpu_destroy(struct kvm_vcpu *vcpu)
 	free_page((unsigned long)vcpu->run);
 	kmem_cache_free(kvm_vcpu_cache, vcpu);
 }
-EXPORT_SYMBOL_GPL(kvm_vcpu_destroy);
+
+void kvm_destroy_vcpus(struct kvm *kvm)
+{
+	unsigned int i;
+	struct kvm_vcpu *vcpu;
+
+	kvm_for_each_vcpu(i, vcpu, kvm)
+		kvm_vcpu_destroy(vcpu);
+
+	mutex_lock(&kvm->lock);
+	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
+		kvm->vcpus[i] = NULL;
+
+	atomic_set(&kvm->online_vcpus, 0);
+	mutex_unlock(&kvm->lock);
+}
+EXPORT_SYMBOL_GPL(kvm_destroy_vcpus);
 
 #if defined(CONFIG_MMU_NOTIFIER) && defined(KVM_ARCH_WANT_MMU_NOTIFIER)
 static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn)

-- 
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