From 6ef7a1bc45f80fe0a263119d404688c596ea5031 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 8 Dec 2008 20:28:04 +1030 Subject: KVM: use modern cpumask primitives, no cpumask_t on stack We're getting rid on on-stack cpumasks for large NR_CPUS. 1) Use cpumask_var_t/alloc_cpumask_var. 2) smp_call_function_mask -> smp_call_function_many 3) cpus_clear, cpus_empty, cpu_set -> cpumask_clear, cpumask_empty, cpumask_set_cpu. This actually generates slightly smaller code than the old one with CONFIG_CPUMASKS_OFFSTACK=n. (gcc knows that cpus cannot be NULL in that case, where cpumask_var_t is cpumask_t[1]). Signed-off-by: Rusty Russell Signed-off-by: Avi Kivity --- virt/kvm/kvm_main.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index ba4275d06fb7..2d6ca7968d65 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -555,12 +555,14 @@ static void ack_flush(void *_completed) static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) { int i, cpu, me; - cpumask_t cpus; - bool called = false; + cpumask_var_t cpus; + bool called = true; struct kvm_vcpu *vcpu; + if (alloc_cpumask_var(&cpus, GFP_ATOMIC)) + cpumask_clear(cpus); + me = get_cpu(); - cpus_clear(cpus); for (i = 0; i < KVM_MAX_VCPUS; ++i) { vcpu = kvm->vcpus[i]; if (!vcpu) @@ -568,14 +570,17 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req) if (test_and_set_bit(req, &vcpu->requests)) continue; cpu = vcpu->cpu; - if (cpu != -1 && cpu != me) - cpu_set(cpu, cpus); - } - if (!cpus_empty(cpus)) { - smp_call_function_mask(cpus, ack_flush, NULL, 1); - called = true; + if (cpus != NULL && cpu != -1 && cpu != me) + cpumask_set_cpu(cpu, cpus); } + if (unlikely(cpus == NULL)) + smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1); + else if (!cpumask_empty(cpus)) + smp_call_function_many(cpus, ack_flush, NULL, 1); + else + called = false; put_cpu(); + free_cpumask_var(cpus); return called; } -- cgit v1.2.1