On 10/30/25 5:59 PM, Sebastian Ott wrote:
> Provide a kvm specific vcpu property to override the default
> (as of kernel v6.13 that would be PSCI v1.3) PSCI version emulated
> by kvm. Current valid values are: 0.1, 0.2, 1.0, 1.1, 1.2, and 1.3
>
> Signed-off-by: Sebastian Ott <[email protected]>
> ---
> docs/system/arm/cpu-features.rst | 5 +++
> target/arm/cpu.h | 6 ++++
> target/arm/kvm.c | 60 +++++++++++++++++++++++++++++++-
> 3 files changed, 70 insertions(+), 1 deletion(-)
>
> diff --git a/docs/system/arm/cpu-features.rst
> b/docs/system/arm/cpu-features.rst
> index 37d5dfd15b..1d32ce0fee 100644
> --- a/docs/system/arm/cpu-features.rst
> +++ b/docs/system/arm/cpu-features.rst
> @@ -204,6 +204,11 @@ the list of KVM VCPU features and their descriptions.
> the guest scheduler behavior and/or be exposed to the guest
> userspace.
>
> +``kvm-psci-version``
> + Override the default (as of kernel v6.13 that would be PSCI v1.3)
> + PSCI version emulated by the kernel. Current valid values are:
> + 0.1, 0.2, 1.0, 1.1, 1.2, and 1.3
> +
> TCG VCPU Features
> =================
>
> diff --git a/target/arm/cpu.h b/target/arm/cpu.h
> index 39f2b2e54d..c2032070b7 100644
> --- a/target/arm/cpu.h
> +++ b/target/arm/cpu.h
> @@ -981,6 +981,12 @@ struct ArchCPU {
> */
> uint32_t psci_version;
>
> + /*
> + * Intermediate value used during property parsing.
> + * Once finalized, the value should be read from psci_version.
> + */
> + uint32_t prop_psci_version;
> +
> /* Current power state, access guarded by BQL */
> ARMPSCIState power_state;
>
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index 0d57081e69..c53b307b76 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -484,6 +484,49 @@ static void kvm_steal_time_set(Object *obj, bool value,
> Error **errp)
> ARM_CPU(obj)->kvm_steal_time = value ? ON_OFF_AUTO_ON : ON_OFF_AUTO_OFF;
> }
>
> +struct psci_version {
> + uint32_t number;
> + const char *str;
> +};
> +
> +static const struct psci_version psci_versions[] = {
> + { QEMU_PSCI_VERSION_0_1, "0.1" },
> + { QEMU_PSCI_VERSION_0_2, "0.2" },
> + { QEMU_PSCI_VERSION_1_0, "1.0" },
> + { QEMU_PSCI_VERSION_1_1, "1.1" },
> + { QEMU_PSCI_VERSION_1_2, "1.2" },
> + { QEMU_PSCI_VERSION_1_3, "1.3" },
> + { -1, NULL },
> +};
> +
> +static char *kvm_get_psci_version(Object *obj, Error **errp)
> +{
> + ARMCPU *cpu = ARM_CPU(obj);
> + const struct psci_version *ver;
> +
> + for (ver = psci_versions; ver->number != -1; ver++) {
> + if (ver->number == cpu->prop_psci_version)
I still have the same question/comment as on v1. In case the end user
does not override the psci version I think you want to return the
default value, retrieved from KVM through KVM_REG_ARM_PSCI_VERSION and
which populates cpu->psci_version. So to me you should use
cpu->psci_version instead
> + return g_strdup(ver->str);
> + }
> +
> + g_assert_not_reached();
> +}
> +
> +static void kvm_set_psci_version(Object *obj, const char *value, Error
> **errp)
> +{
> + ARMCPU *cpu = ARM_CPU(obj);
> + const struct psci_version *ver;
> +
> + for (ver = psci_versions; ver->number != -1; ver++) {
> + if (!strcmp(value, ver->str)) {
> + cpu->prop_psci_version = ver->number;
> + return;
> + }
> + }
> +
> + error_setg(errp, "Invalid PSCI-version value");
> +}
> +
> /* KVM VCPU properties should be prefixed with "kvm-". */
> void kvm_arm_add_vcpu_properties(ARMCPU *cpu)
> {
> @@ -505,6 +548,12 @@ void kvm_arm_add_vcpu_properties(ARMCPU *cpu)
> kvm_steal_time_set);
> object_property_set_description(obj, "kvm-steal-time",
> "Set off to disable KVM steal time.");
> +
> + object_property_add_str(obj, "kvm-psci-version", kvm_get_psci_version,
> + kvm_set_psci_version);
> + object_property_set_description(obj, "kvm-psci-version",
> + "Set PSCI version. "
> + "Valid values are 0.1, 0.2, 1.0, 1.1,
> 1.2, 1.3");
> }
>
> bool kvm_arm_pmu_supported(void)
> @@ -1959,7 +2008,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
> if (cs->start_powered_off) {
> cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_POWER_OFF;
> }
> - if (kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PSCI_0_2)) {
> + if (cpu->prop_psci_version != QEMU_PSCI_VERSION_0_1 &&
I don't understand what this change stands for. Please document it
through both a comment and a commit msg explanation
Thanks
Eric
> + kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PSCI_0_2)) {
> cpu->psci_version = QEMU_PSCI_VERSION_0_2;
> cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PSCI_0_2;
> }
> @@ -1998,6 +2048,14 @@ int kvm_arch_init_vcpu(CPUState *cs)
> }
> }
>
> + if (cpu->prop_psci_version) {
> + psciver = cpu->prop_psci_version;
> + ret = kvm_set_one_reg(cs, KVM_REG_ARM_PSCI_VERSION, &psciver);
> + if (ret) {
> + error_report("PSCI version %"PRIx64" is not supported by KVM",
> psciver);
> + return ret;
> + }
> + }
> /*
> * KVM reports the exact PSCI version it is implementing via a
> * special sysreg. If it is present, use its contents to determine
