[PATCH 5/6] kvm: allocate vcpu pointer array separately

From: Juergen Gross <jgross@suse.com>
Date: 2021-07-01 15:41:26
Also in: kvm, kvmarm, lkml
Subsystem: arm64 port (aarch64 architecture), kernel virtual machine (kvm), kernel virtual machine for arm64 (kvm/arm64), kernel virtual machine for x86 (kvm/x86), the rest, x86 architecture (32-bit and 64-bit) · Maintainers: Catalin Marinas, Will Deacon, Paolo Bonzini, Marc Zyngier, Oliver Upton, Sean Christopherson, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen

Prepare support of very large vcpu numbers per guest by moving the
vcpu pointer array out of struct kvm.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/arm64/kvm/arm.c            | 28 ++++++++++++++++++++++++----
 arch/x86/include/asm/kvm_host.h |  5 +----
 arch/x86/kvm/x86.c              | 19 +++++++++++++++++++
 include/linux/kvm_host.h        | 17 +++++++++++++++--
 4 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e720148232a0..4f055408fe9f 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c

@@ -280,18 +280,38 @@ long kvm_arch_dev_ioctl(struct file *filp,
 
 struct kvm *kvm_arch_alloc_vm(void)
 {
+	struct kvm *kvm;
+
 	if (!has_vhe())
-		return kzalloc(sizeof(struct kvm), GFP_KERNEL);
+		kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
+	else
+		kvm = vzalloc(sizeof(struct kvm));
 
-	return vzalloc(sizeof(struct kvm));
+	if (!kvm)
+		return NULL;
+
+	if (!has_vhe())
+		kvm->vcpus = kcalloc(KVM_MAX_VCPUS, sizeof(void *), GFP_KERNEL);
+	else
+		kvm->vcpus = vzalloc(KVM_MAX_VCPUS * sizeof(void *));
+
+	if (!kvm->vcpus) {
+		kvm_arch_free_vm(kvm);
+		kvm = NULL;
+	}
+
+	return kvm;
 }
 
 void kvm_arch_free_vm(struct kvm *kvm)
 {
-	if (!has_vhe())
+	if (!has_vhe()) {
+		kfree(kvm->vcpus);
 		kfree(kvm);
-	else
+	} else {
+		vfree(kvm->vcpus);
 		vfree(kvm);
+	}
 }
 
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 79138c91f83d..39cbc4b6bffb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h

@@ -1440,10 +1440,7 @@ static inline void kvm_ops_static_call_update(void)
 }
 
 #define __KVM_HAVE_ARCH_VM_ALLOC
-static inline struct kvm *kvm_arch_alloc_vm(void)
-{
-	return __vmalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
-}
+struct kvm *kvm_arch_alloc_vm(void);
 void kvm_arch_free_vm(struct kvm *kvm);
 
 #define __KVM_HAVE_ARCH_FLUSH_REMOTE_TLB

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3af398ef1fc9..a9b0bb2221ea 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c

@@ -10741,9 +10741,28 @@ void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu)
 	static_call(kvm_x86_sched_in)(vcpu, cpu);
 }
 
+struct kvm *kvm_arch_alloc_vm(void)
+{
+	struct kvm *kvm;
+
+	kvm = __vmalloc(kvm_x86_ops.vm_size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	if (!kvm)
+		return NULL;
+
+	kvm->vcpus = __vmalloc(KVM_MAX_VCPUS * sizeof(void *),
+			       GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	if (!kvm->vcpus) {
+		vfree(kvm);
+		kvm = NULL;
+	}
+
+	return kvm;
+}
+
 void kvm_arch_free_vm(struct kvm *kvm)
 {
 	kfree(to_kvm_hv(kvm)->hv_pa_pg);
+	vfree(kvm->vcpus);
 	vfree(kvm);
 }

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8583ed3ff344..e424ef1078a1 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h

@@ -525,7 +525,7 @@ struct kvm {
 	struct mutex slots_lock;
 	struct mm_struct *mm; /* userspace tied to this vm */
 	struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM];
-	struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
+	struct kvm_vcpu **vcpus;
 
 	/*
 	 * created_vcpus is protected by kvm->lock, and is incremented

@@ -1022,11 +1022,24 @@ void kvm_arch_pre_destroy_vm(struct kvm *kvm);
  */
 static inline struct kvm *kvm_arch_alloc_vm(void)
 {
-	return kzalloc(sizeof(struct kvm), GFP_KERNEL);
+	struct kvm *kvm = kzalloc(sizeof(struct kvm), GFP_KERNEL);
+
+	if (!kvm)
+		return NULL;
+
+	kvm->vcpus = kcalloc(KVM_MAX_VCPUS, sizeof(void *), GFP_KERNEL);
+	if (!kvm->vcpus) {
+		kfree(kvm);
+		kvm = NULL;
+	}
+
+	return kvm;
 }
 
 static inline void kvm_arch_free_vm(struct kvm *kvm)
 {
+	if (kvm)
+		kfree(kvm->vcpus);
 	kfree(kvm);
 }
 #endif

-- 
2.26.2


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