Commit baff59cc authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Paolo Bonzini
Browse files

KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except() 



Allocating cpumask dynamically in zalloc_cpumask_var() is not ideal.
Allocation is somewhat slow and can (in theory and when CPUMASK_OFFSTACK)
fail. kvm_make_all_cpus_request_except() already disables preemption so
we can use pre-allocated per-cpu cpumasks instead.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-8-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 381cecc5

virt/kvm/kvm_main.c

+23 −6
Original line number Original line Diff line number Diff line
@@ -155,6 +155,8 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm); 
static unsigned long long kvm_createvm_count;

static unsigned long long kvm_createvm_count;

static unsigned long long kvm_active_vms;

static unsigned long long kvm_active_vms;





static DEFINE_PER_CPU(cpumask_var_t, cpu_kick_mask);



__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,

__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,

						   unsigned long start, unsigned long end)

						   unsigned long start, unsigned long end)

{

{
@@ -313,14 +315,15 @@ bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req, 
				      struct kvm_vcpu *except)

				      struct kvm_vcpu *except)

{

{

	struct kvm_vcpu *vcpu;

	struct kvm_vcpu *vcpu;

	cpumask_var_t cpus;

	struct cpumask *cpus;

	bool called;

	bool called;

	int i, me;

	int i, me;





	zalloc_cpumask_var(&cpus, GFP_ATOMIC);



	me = get_cpu();

	me = get_cpu();





	cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);

	cpumask_clear(cpus);



	kvm_for_each_vcpu(i, vcpu, kvm) {

	kvm_for_each_vcpu(i, vcpu, kvm) {

		if (vcpu == except)

		if (vcpu == except)

			continue;

			continue;
@@ -330,7 +333,6 @@ bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req, 
	called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));

	called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));

	put_cpu();

	put_cpu();





	free_cpumask_var(cpus);

	return called;

	return called;

}

}
@@ -5560,9 +5562,17 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, 
		goto out_free_3;

		goto out_free_3;

	}

	}





	for_each_possible_cpu(cpu) {

		if (!alloc_cpumask_var_node(&per_cpu(cpu_kick_mask, cpu),

					    GFP_KERNEL, cpu_to_node(cpu))) {

			r = -ENOMEM;

			goto out_free_4;

		}

	}



	r = kvm_async_pf_init();

	r = kvm_async_pf_init();

	if (r)

	if (r)

		goto out_free;

		goto out_free_5;





	kvm_chardev_ops.owner = module;

	kvm_chardev_ops.owner = module;

	kvm_vm_fops.owner = module;

	kvm_vm_fops.owner = module;
@@ -5588,7 +5598,10 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align, 




out_unreg:

out_unreg:

	kvm_async_pf_deinit();

	kvm_async_pf_deinit();

out_free:

out_free_5:

	for_each_possible_cpu(cpu)

		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));

out_free_4:

	kmem_cache_destroy(kvm_vcpu_cache);

	kmem_cache_destroy(kvm_vcpu_cache);

out_free_3:

out_free_3:

	unregister_reboot_notifier(&kvm_reboot_notifier);

	unregister_reboot_notifier(&kvm_reboot_notifier);
@@ -5608,8 +5621,12 @@ EXPORT_SYMBOL_GPL(kvm_init); 




void kvm_exit(void)

void kvm_exit(void)

{

{

	int cpu;



	debugfs_remove_recursive(kvm_debugfs_dir);

	debugfs_remove_recursive(kvm_debugfs_dir);

	misc_deregister(&kvm_dev);

	misc_deregister(&kvm_dev);

	for_each_possible_cpu(cpu)

		free_cpumask_var(per_cpu(cpu_kick_mask, cpu));

	kmem_cache_destroy(kvm_vcpu_cache);

	kmem_cache_destroy(kvm_vcpu_cache);

	kvm_async_pf_deinit();

	kvm_async_pf_deinit();

	unregister_syscore_ops(&kvm_syscore_ops);

	unregister_syscore_ops(&kvm_syscore_ops);