[PATCH 07/16] ARM/ARM64: KVM: Emulate PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET

Christoffer Dall
2014-05-25T18:19:24Z

From: Anup Patel <anup.patel@linaro.org>

The PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET functions are system-level
functions hence cannot be fully emulated by in-kernel PSCI emulation code.

To tackle this, we forward PSCI v0.2 SYSTEM_OFF and SYSTEM_RESET function
calls from vcpu to user space (i.e. QEMU or KVMTOOL) via kvm_run structure
using KVM_EXIT_SYSTEM_EVENT exit reasons.

Signed-off-by: Anup Patel <anup.patel@linaro.org>
Signed-off-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
---
arch/arm/kvm/psci.c | 46 +++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 43 insertions(+), 3 deletions(-)

diff --git a/arch/arm/kvm/psci.c b/arch/arm/kvm/psci.c
index 14e6fa6..5936213 100644
--- a/arch/arm/kvm/psci.c
+++ b/arch/arm/kvm/psci.c
@@ -85,6 +85,23 @@ static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
return PSCI_RET_SUCCESS;
}

+static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
+{
+ 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;
+}
+
+static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
+{
+ kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
+}
+
+static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
+{
+ kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
+}
+
int kvm_psci_version(struct kvm_vcpu *vcpu)
{
if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
@@ -95,6 +112,7 @@ int kvm_psci_version(struct kvm_vcpu *vcpu)

static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{
+ int ret = 1;
unsigned long psci_fn = *vcpu_reg(vcpu, 0) & ~((u32) 0);
unsigned long val;

@@ -114,13 +132,35 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
case PSCI_0_2_FN64_CPU_ON:
val = kvm_psci_vcpu_on(vcpu);
break;
+ case PSCI_0_2_FN_SYSTEM_OFF:
+ kvm_psci_system_off(vcpu);
+ /*
+ * We should'nt be going back to guest VCPU after
+ * receiving SYSTEM_OFF request.
+ *
+ * If user space accidently/deliberately resumes
+ * guest VCPU after SYSTEM_OFF request then guest
+ * VCPU should see internal failure from PSCI return
+ * value. To achieve this, we preload r0 (or x0) with
+ * PSCI return value INTERNAL_FAILURE.
+ */
+ val = PSCI_RET_INTERNAL_FAILURE;
+ ret = 0;
+ break;
+ case PSCI_0_2_FN_SYSTEM_RESET:
+ kvm_psci_system_reset(vcpu);
+ /*
+ * Same reason as SYSTEM_OFF for preloading r0 (or x0)
+ * with PSCI return value INTERNAL_FAILURE.
+ */
+ val = PSCI_RET_INTERNAL_FAILURE;
+ ret = 0;
+ break;
case PSCI_0_2_FN_CPU_SUSPEND:
case PSCI_0_2_FN_AFFINITY_INFO:
case PSCI_0_2_FN_MIGRATE:
case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
case PSCI_0_2_FN_MIGRATE_INFO_UP_CPU:
- case PSCI_0_2_FN_SYSTEM_OFF:
- case PSCI_0_2_FN_SYSTEM_RESET:
case PSCI_0_2_FN64_CPU_SUSPEND:
case PSCI_0_2_FN64_AFFINITY_INFO:
case PSCI_0_2_FN64_MIGRATE:
@@ -132,7 +172,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
}

*vcpu_reg(vcpu, 0) = val;
- return 1;
+ return ret;
}

static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
--
1.8.5.2