| Message ID | 20240924160512.4138879-2-dwmw2@infradead.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v4,1/6] firmware/psci: Add definitions for PSCI v1.3 specification | expand |
On Tue, 2024-09-24 at 17:05 +0100, David Woodhouse wrote: > From: David Woodhouse <dwmw@amazon.co.uk> > > The PSCI v1.3 specification (alpha) adds support for a SYSTEM_OFF2 Can remove (alpha). > 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). > > The beta version will be changed to say that PSCI_FEATURES returns a > bit > mask of the supported hibernate types, which is implemented here. Since the final spec has been released, we can revise or remove the above wording. > Although this new feature is inflicted unconditionally on unexpecting > userspace, it ought to be mostly 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). The spec says that the HIBERNATE_OFF parameter value is 0x1, not 0x0 (which is kind of unfortunate because it doesn't match the corresponding bit in the feature flags). So, either the BIT(PSCI_1_3_HIBERNATE_TYPE_OFF) value should be used for the SYSTEM_OFF2 functions in the code, or the definition should be changed in the header file (unless the text in the spec is wrong).
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); }