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authorVitaly Kuznetsov <vkuznets@redhat.com>2021-09-03 09:51:41 +0200
committerPaolo Bonzini <pbonzini@redhat.com>2021-09-30 04:27:04 -0400
commit620b2438abf98f09e19802cbc3bc2e98179cdbe2 (patch)
tree27b1d04b869efb98267ae18f4fed3c6e75cf2580 /virt
parentbaff59ccdc657d290be51b95b38ebe5de40036b4 (diff)
KVM: Make kvm_make_vcpus_request_mask() use pre-allocated cpu_kick_mask
kvm_make_vcpus_request_mask() already disables preemption so just like kvm_make_all_cpus_request_except() it can be switched to using pre-allocated per-cpu cpumasks. This allows for improvements for both users of the function: in Hyper-V emulation code 'tlb_flush' can now be dropped from 'struct kvm_vcpu_hv' and kvm_make_scan_ioapic_request_mask() gets rid of dynamic allocation. cpumask_available() checks in kvm_make_vcpu_request() and kvm_kick_many_cpus() can now be dropped as they checks for an impossible condition: kvm_init() makes sure per-cpu masks are allocated. Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210903075141.403071-9-vkuznets@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c29
1 files changed, 9 insertions, 20 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9cb0fd1723e6..18d245fe2118 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -237,15 +237,8 @@ static void ack_flush(void *_completed)
{
}
-static inline bool kvm_kick_many_cpus(cpumask_var_t tmp, bool wait)
+static inline bool kvm_kick_many_cpus(struct cpumask *cpus, bool wait)
{
- const struct cpumask *cpus;
-
- if (likely(cpumask_available(tmp)))
- cpus = tmp;
- else
- cpus = cpu_online_mask;
-
if (cpumask_empty(cpus))
return false;
@@ -254,7 +247,7 @@ static inline bool kvm_kick_many_cpus(cpumask_var_t tmp, bool wait)
}
static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
- unsigned int req, cpumask_var_t tmp,
+ unsigned int req, struct cpumask *tmp,
int current_cpu)
{
int cpu;
@@ -265,14 +258,6 @@ static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
return;
/*
- * tmp can be "unavailable" if cpumasks are allocated off stack as
- * allocation of the mask is deliberately not fatal and is handled by
- * falling back to kicking all online CPUs.
- */
- if (!cpumask_available(tmp))
- return;
-
- /*
* Note, the vCPU could get migrated to a different pCPU at any point
* after kvm_request_needs_ipi(), which could result in sending an IPI
* to the previous pCPU. But, that's OK because the purpose of the IPI
@@ -290,22 +275,26 @@ static void kvm_make_vcpu_request(struct kvm *kvm, struct kvm_vcpu *vcpu,
}
bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req,
- unsigned long *vcpu_bitmap, cpumask_var_t tmp)
+ unsigned long *vcpu_bitmap)
{
struct kvm_vcpu *vcpu;
+ struct cpumask *cpus;
int i, me;
bool called;
me = get_cpu();
+ cpus = this_cpu_cpumask_var_ptr(cpu_kick_mask);
+ cpumask_clear(cpus);
+
for_each_set_bit(i, vcpu_bitmap, KVM_MAX_VCPUS) {
vcpu = kvm_get_vcpu(kvm, i);
if (!vcpu)
continue;
- kvm_make_vcpu_request(kvm, vcpu, req, tmp, me);
+ kvm_make_vcpu_request(kvm, vcpu, req, cpus, me);
}
- called = kvm_kick_many_cpus(tmp, !!(req & KVM_REQUEST_WAIT));
+ called = kvm_kick_many_cpus(cpus, !!(req & KVM_REQUEST_WAIT));
put_cpu();
return called;