arm/arm64: KVM: Turn off vcpus on PSCI shutdown/reboot

When a vcpu calls SYSTEM_OFF or SYSTEM_RESET with PSCI v0.2, the vcpus
should really be turned off for the VM adhering to the suggestions in
the PSCI spec, and it's the sane thing to do.

Also, clarify the behavior and expectations for exits to user space with
the KVM_EXIT_SYSTEM_EVENT case.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 81f1b974c06a5c8d18e2f3a22ed91862ffff154b..228f9cf5a5b5ebb9fd1571f944a30cfa3056ab71 100644 (file)
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2957,6 +2957,15 @@ HVC instruction based PSCI call from the vcpu. The 'type' field describes
 the system-level event type. The 'flags' field describes architecture
 specific flags for the system-level event.
 
+Valid values for 'type' are:
+  KVM_SYSTEM_EVENT_SHUTDOWN -- the guest has requested a shutdown of the
+   VM. Userspace is not obliged to honour this, and if it does honour
+   this does not need to destroy the VM synchronously (ie it may call
+   KVM_RUN again before shutdown finally occurs).
+  KVM_SYSTEM_EVENT_RESET -- the guest has requested a reset of the VM.
+   As with SHUTDOWN, userspace can choose to ignore the request, or
+   to schedule the reset to occur in the future and may call KVM_RUN again.
+
                /* Fix the size of the union. */
                char padding[256];
        };

diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index 09cf37737ee2ad24bda1251541689ea2f8bdb535..58cb3248d277bc03a6b38850a558186a34606205 100644 (file)
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -15,6 +15,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <linux/preempt.h>
 #include <linux/kvm_host.h>
 #include <linux/wait.h>
 
@@ -166,6 +167,23 @@ static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
 
 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
 {
+       int i;
+       struct kvm_vcpu *tmp;
+
+       /*
+        * The KVM ABI specifies that a system event exit may call KVM_RUN
+        * again and may perform shutdown/reboot at a later time that when the
+        * actual request is made.  Since we are implementing PSCI and a
+        * caller of PSCI reboot and shutdown expects that the system shuts
+        * down or reboots immediately, let's make sure that VCPUs are not run
+        * after this call is handled and before the VCPUs have been
+        * re-initialized.
+        */
+       kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+               tmp->arch.pause = true;
+               kvm_vcpu_kick(tmp);
+       }
+
        memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
        vcpu->run->system_event.type = type;
        vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 65c615294589f242a2d62694695002882d5cc1a8..0b7dfdb931dff6f9610df181015ce7ecc1a7f16a 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -198,6 +198,7 @@ struct kvm_vcpu *kvm_arm_get_running_vcpu(void);
 struct kvm_vcpu * __percpu *kvm_get_running_vcpus(void);
 
 u64 kvm_call_hyp(void *hypfn, ...);
+void force_vm_exit(const cpumask_t *mask);
 
 int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
                int exception_index);