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-rw-r--r--virt/kvm/kvm_main.c36
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);