diff options
-rw-r--r-- | virt/kvm/kvm_main.c | 36 |
1 files changed, 28 insertions, 8 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8495a01d1e41..490c8cb8cc8d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -263,14 +263,26 @@ bool kvm_make_vcpus_request_mask(struct kvm *kvm, unsigned int req, continue; kvm_make_request(req, vcpu); - cpu = vcpu->cpu; if (!(req & KVM_REQUEST_NO_WAKEUP) && kvm_vcpu_wake_up(vcpu)) continue; - if (tmp != NULL && cpu != -1 && cpu != me && - kvm_request_needs_ipi(vcpu, req)) - __cpumask_set_cpu(cpu, tmp); + /* + * 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 is to ensure the vCPU returns to + * OUTSIDE_GUEST_MODE, which is satisfied if the vCPU migrates. + * Entering READING_SHADOW_PAGE_TABLES after this point is also + * ok, as the requirement is only that KVM wait for vCPUs that + * 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)) { + cpu = READ_ONCE(vcpu->cpu); + if (cpu != -1 && cpu != me) + __cpumask_set_cpu(cpu, tmp); + } } called = kvm_kick_many_cpus(tmp, !!(req & KVM_REQUEST_WAIT)); @@ -3294,16 +3306,24 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_wake_up); */ void kvm_vcpu_kick(struct kvm_vcpu *vcpu) { - int me; - int cpu = vcpu->cpu; + int me, cpu; if (kvm_vcpu_wake_up(vcpu)) return; + /* + * Note, the vCPU could get migrated to a different pCPU at any point + * after kvm_arch_vcpu_should_kick(), which could result in sending an + * IPI to the previous pCPU. But, that's ok because the purpose of the + * IPI is to force the vCPU to leave IN_GUEST_MODE, and migrating the + * vCPU also requires it to leave IN_GUEST_MODE. + */ me = get_cpu(); - if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) - if (kvm_arch_vcpu_should_kick(vcpu)) + if (kvm_arch_vcpu_should_kick(vcpu)) { + cpu = READ_ONCE(vcpu->cpu); + if (cpu != me && (unsigned)cpu < nr_cpu_ids && cpu_online(cpu)) smp_send_reschedule(cpu); + } put_cpu(); } EXPORT_SYMBOL_GPL(kvm_vcpu_kick); |