diff options
| author | Sean Christopherson <seanjc@google.com> | 2021-08-27 11:25:10 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-09-22 10:33:15 -0400 |
| commit | 0bbc2ca8515f9cdf11df84ccb63dc7c44bc3d8f4 (patch) | |
| tree | f28f7a59b2f13d18d3c9038dd82b6ad50b66e761 | |
| parent | 85b640450ddcfa09cf72771b69a9c3daf0ddc772 (diff) | |
KVM: KVM: Use cpumask_available() to check for NULL cpumask when kicking vCPUs
Check for a NULL cpumask_var_t when kicking multiple vCPUs via
cpumask_available(), which performs a !NULL check if and only if cpumasks
are configured to be allocated off-stack. This is a meaningless
optimization, e.g. avoids a TEST+Jcc and TEST+CMOV on x86, but more
importantly helps document that the NULL check is necessary even though
all callers pass in a local variable.
No functional change intended.
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210827092516.1027264-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | virt/kvm/kvm_main.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 490c8cb8cc8d..e95e7a9e4d53 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -235,9 +235,13 @@ static void ack_flush(void *_completed) { } -static inline bool kvm_kick_many_cpus(const struct cpumask *cpus, bool wait) +static inline bool kvm_kick_many_cpus(cpumask_var_t tmp, bool wait) { - if (unlikely(!cpus)) + const struct cpumask *cpus; + + if (likely(cpumask_available(tmp))) + cpus = tmp; + else cpus = cpu_online_mask; if (cpumask_empty(cpus)) @@ -268,6 +272,14 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req, continue; /* + * 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)) + continue; + + /* * 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 @@ -278,7 +290,7 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req, * were reading SPTEs _before_ any changes were finalized. See * kvm_vcpu_kick() for more details on handling requests. */ - if (tmp != NULL && kvm_request_needs_ipi(vcpu, req)) { + if (kvm_request_needs_ipi(vcpu, req)) { cpu = READ_ONCE(vcpu->cpu); if (cpu != -1 && cpu != me) __cpumask_set_cpu(cpu, tmp); |