From: David Woodhouse dwmw@amazon.co.uk
The PSCI v1.3 specification adds support for a SYSTEM_OFF2 function which is analogous to ACPI S4 state. This will allow hosting environments to determine that a guest is hibernated rather than just powered off, and ensure that they preserve the virtual environment appropriately to allow the guest to resume safely (or bump the hardware_signature in the FACS to trigger a clean reboot instead).
Although this new feature is inflicted unconditionally on unexpecting userspace, it should be OK because it still results in the same KVM_SYSTEM_EVENT_SHUTDOWN event, just with a new flag which hopefully won't cause userspace to get unhappy.
Signed-off-by: David Woodhouse dwmw@amazon.co.uk --- Documentation/virt/kvm/api.rst | 11 +++++++++ arch/arm64/include/uapi/asm/kvm.h | 6 +++++ arch/arm64/kvm/psci.c | 37 +++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index b3be87489108..2918898b7047 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6840,6 +6840,10 @@ the first `ndata` items (possibly zero) of the data array are valid. the guest issued a SYSTEM_RESET2 call according to v1.1 of the PSCI specification.
+ - for arm64, data[0] is set to KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2 + if the guest issued a SYSTEM_OFF2 call according to v1.3 of the PSCI + specification. + - for RISC-V, data[0] is set to the value of the second argument of the ``sbi_system_reset`` call.
@@ -6873,6 +6877,13 @@ either: - Deny the guest request to suspend the VM. See ARM DEN0022D.b 5.19.2 "Caller responsibilities" for possible return values.
+Hibernation using the PSCI SYSTEM_OFF2 call is enabled when PSCI v1.3 +is enabled. If a guest invokes the PSCI SYSTEM_OFF2 function, KVM will +exit to userspace with the KVM_SYSTEM_EVENT_SHUTDOWN event type and with +data[0] set to KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2. The only +supported hibernate type for the SYSTEM_OFF2 function is HIBERNATE_OFF +0x0). + ::
/* KVM_EXIT_IOAPIC_EOI */ diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index 964df31da975..66736ff04011 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -484,6 +484,12 @@ enum { */ #define KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2 (1ULL << 0)
+/* + * Shutdown caused by a PSCI v1.3 SYSTEM_OFF2 call. + * Valid only when the system event has a type of KVM_SYSTEM_EVENT_SHUTDOWN. + */ +#define KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2 (1ULL << 0) + /* run->fail_entry.hardware_entry_failure_reason codes. */ #define KVM_EXIT_FAIL_ENTRY_CPU_UNSUPPORTED (1ULL << 0)
diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c index 1f69b667332b..fd0f82464f7d 100644 --- a/arch/arm64/kvm/psci.c +++ b/arch/arm64/kvm/psci.c @@ -194,6 +194,12 @@ static void kvm_psci_system_off(struct kvm_vcpu *vcpu) kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN, 0); }
+static void kvm_psci_system_off2(struct kvm_vcpu *vcpu) +{ + kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN, + KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2); +} + static void kvm_psci_system_reset(struct kvm_vcpu *vcpu) { kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET, 0); @@ -358,6 +364,11 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor) if (minor >= 1) val = 0; break; + case PSCI_1_3_FN_SYSTEM_OFF2: + case PSCI_1_3_FN64_SYSTEM_OFF2: + if (minor >= 3) + val = BIT(PSCI_1_3_HIBERNATE_TYPE_OFF); + break; } break; case PSCI_1_0_FN_SYSTEM_SUSPEND: @@ -392,6 +403,32 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor) break; } break; + case PSCI_1_3_FN_SYSTEM_OFF2: + kvm_psci_narrow_to_32bit(vcpu); + fallthrough; + case PSCI_1_3_FN64_SYSTEM_OFF2: + if (minor < 3) + break; + + arg = smccc_get_arg1(vcpu); + if (arg != PSCI_1_3_HIBERNATE_TYPE_OFF) { + val = PSCI_RET_INVALID_PARAMS; + break; + } + kvm_psci_system_off2(vcpu); + /* + * We shouldn't be going back to guest VCPU after + * receiving SYSTEM_OFF2 request. + * + * If user space accidentally/deliberately resumes + * guest VCPU after SYSTEM_OFF2 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; default: return kvm_psci_0_2_call(vcpu); }