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 Note: in order to support PSCI v0.1 we need to drop vcpu initialization with KVM_CAP_ARM_PSCI_0_2 in that case. Reviewed-by: Eric Auger Tested-by: Eric Auger Signed-off-by: Sebastian Ott --- docs/system/arm/cpu-features.rst | 11 ++++++++ target/arm/cpu.c | 8 +++++- target/arm/kvm.c | 48 ++++++++++++++++++++++++++++++-- 3 files changed, 64 insertions(+), 3 deletions(-) diff --git a/docs/system/arm/cpu-features.rst b/docs/system/arm/cpu-features.rst index 3db1f19401..ce19ae6a04 100644 --- a/docs/system/arm/cpu-features.rst +++ b/docs/system/arm/cpu-features.rst @@ -204,6 +204,17 @@ the list of KVM VCPU features and their descriptions. the guest scheduler behavior and/or be exposed to the guest userspace. +``kvm-psci-version`` + Set the Power State Coordination Interface (PSCI) firmware ABI version + that KVM provides to the guest. By default KVM will use the newest + version that it knows about (which is PSCI v1.3 in Linux v6.13). + + You only need to set this if you want to be able to migrate this + VM to a host machine running an older kernel that does not + recognize the PSCI version that this host's kernel defaults to. + + 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.c b/target/arm/cpu.c index 10f8280eef..60f391651d 100644 --- a/target/arm/cpu.c +++ b/target/arm/cpu.c @@ -1144,7 +1144,13 @@ static void arm_cpu_initfn(Object *obj) * picky DTB consumer will also provide a helpful error message. */ cpu->dtb_compatible = "qemu,unknown"; - cpu->psci_version = QEMU_PSCI_VERSION_0_1; /* By default assume PSCI v0.1 */ + if (!kvm_enabled()) { + /* By default KVM will use the newest PSCI version that it knows about. + * This can be changed using the kvm-psci-version property. + * For others assume PSCI v0.1 by default. + */ + cpu->psci_version = QEMU_PSCI_VERSION_0_1; + } cpu->kvm_target = QEMU_KVM_ARM_TARGET_NONE; if (tcg_enabled() || hvf_enabled()) { diff --git a/target/arm/kvm.c b/target/arm/kvm.c index ded582e0da..5453460965 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -485,6 +485,28 @@ 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; } +static char *kvm_get_psci_version(Object *obj, Error **errp) +{ + ARMCPU *cpu = ARM_CPU(obj); + + return g_strdup_printf("%d.%d", + (int) PSCI_VERSION_MAJOR(cpu->psci_version), + (int) PSCI_VERSION_MINOR(cpu->psci_version)); +} + +static void kvm_set_psci_version(Object *obj, const char *value, Error **errp) +{ + ARMCPU *cpu = ARM_CPU(obj); + uint16_t maj, min; + + if (sscanf(value, "%hd.%hd", &maj, &min) != 2) { + error_setg(errp, "Invalid PSCI version."); + return; + } + + cpu->psci_version = PSCI_VERSION(maj, min); +} + /* KVM VCPU properties should be prefixed with "kvm-". */ void kvm_arm_add_vcpu_properties(ARMCPU *cpu) { @@ -506,6 +528,12 @@ 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) @@ -1976,8 +2004,12 @@ 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)) { - cpu->psci_version = QEMU_PSCI_VERSION_0_2; + if (cpu->psci_version != QEMU_PSCI_VERSION_0_1 && + kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PSCI_0_2)) { + /* + * Versions >= v0.2 are backward compatible with v0.2 + * omit the feature flag for v0.1 . + */ cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PSCI_0_2; } if (!arm_feature(env, ARM_FEATURE_AARCH64)) { @@ -2015,6 +2047,18 @@ int kvm_arch_init_vcpu(CPUState *cs) } } + if (cpu->psci_version) { + psciver = cpu->psci_version; + ret = kvm_set_one_reg(cs, KVM_REG_ARM_PSCI_VERSION, &psciver); + if (ret) { + error_report("KVM in this kernel does not support PSCI version %d.%d", + (int) PSCI_VERSION_MAJOR(psciver), + (int) PSCI_VERSION_MINOR(psciver)); + error_printf("Consider setting the kvm-psci-version property on the " + "migration source.\n"); + return ret; + } + } /* * KVM reports the exact PSCI version it is implementing via a * special sysreg. If it is present, use its contents to determine -- 2.52.0