From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Nitesh Narayan Lal <nitesh@redhat.com>,
Lai Jiangshan <jiangshanlai@gmail.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH v4 7/8] KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except()
Date: Fri, 27 Aug 2021 11:25:15 +0200 [thread overview]
Message-ID: <20210827092516.1027264-8-vkuznets@redhat.com> (raw)
In-Reply-To: <20210827092516.1027264-1-vkuznets@redhat.com>
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: Vitaly Kuznetsov <vkuznets@redhat.com>
---
virt/kvm/kvm_main.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2e9927c4eb32..2f5fe4f54a51 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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_active_vms;
+static DEFINE_PER_CPU(cpumask_var_t, cpu_kick_mask);
+
__weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm,
unsigned long start, unsigned long end)
{
@@ -323,14 +325,15 @@ bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
struct kvm_vcpu *except)
{
struct kvm_vcpu *vcpu;
- cpumask_var_t cpus;
+ struct cpumask *cpus;
bool called;
int i, me;
- zalloc_cpumask_var(&cpus, GFP_ATOMIC);
-
me = get_cpu();
+ cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
+ cpumask_clear(cpus);
+
kvm_for_each_vcpu(i, vcpu, kvm) {
if (vcpu == except)
continue;
@@ -340,7 +343,6 @@ bool kvm_make_all_cpus_request_except(struct kvm *kvm, unsigned int req,
called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
put_cpu();
- free_cpumask_var(cpus);
return called;
}
@@ -5581,9 +5583,15 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
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)))
+ goto out_free_4;
+ }
+
r = kvm_async_pf_init();
if (r)
- goto out_free;
+ goto out_free_5;
kvm_chardev_ops.owner = module;
kvm_vm_fops.owner = module;
@@ -5609,7 +5617,11 @@ int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
out_unreg:
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);
out_free_3:
unregister_reboot_notifier(&kvm_reboot_notifier);
@@ -5629,8 +5641,13 @@ EXPORT_SYMBOL_GPL(kvm_init);
void kvm_exit(void)
{
+ int cpu;
+
debugfs_remove_recursive(kvm_debugfs_dir);
misc_deregister(&kvm_dev);
+ for_each_possible_cpu(cpu) {
+ free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
+ }
kmem_cache_destroy(kvm_vcpu_cache);
kvm_async_pf_deinit();
unregister_syscore_ops(&kvm_syscore_ops);
--
2.31.1
next prev parent reply other threads:[~2021-08-27 9:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-27 9:25 [PATCH v4 0/8] KVM: Various fixes and improvements around kicking vCPUs Vitaly Kuznetsov
2021-08-27 9:25 ` [PATCH v4 1/8] KVM: Clean up benign vcpu->cpu data races when " Vitaly Kuznetsov
2021-08-27 9:25 ` [PATCH v4 2/8] KVM: KVM: Use cpumask_available() to check for NULL cpumask " Vitaly Kuznetsov
2021-08-27 9:25 ` [PATCH v4 3/8] KVM: x86: hyper-v: Avoid calling kvm_make_vcpus_request_mask() with vcpu_mask==NULL Vitaly Kuznetsov
2021-09-02 20:57 ` Sean Christopherson
2021-08-27 9:25 ` [PATCH v4 4/8] KVM: Optimize kvm_make_vcpus_request_mask() a bit Vitaly Kuznetsov
2021-09-02 21:00 ` Sean Christopherson
2021-08-27 9:25 ` [PATCH v4 5/8] KVM: Drop 'except' parameter from kvm_make_vcpus_request_mask() Vitaly Kuznetsov
2021-09-02 21:00 ` Sean Christopherson
2021-08-27 9:25 ` [PATCH v4 6/8] KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() Vitaly Kuznetsov
2021-08-27 9:25 ` Vitaly Kuznetsov [this message]
2021-09-02 21:08 ` [PATCH v4 7/8] KVM: Pre-allocate cpumasks for kvm_make_all_cpus_request_except() Sean Christopherson
2021-09-03 7:20 ` Vitaly Kuznetsov
2021-09-03 14:54 ` Sean Christopherson
2021-08-27 9:25 ` [PATCH v4 8/8] KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask Vitaly Kuznetsov
2021-09-02 21:19 ` Sean Christopherson
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