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[2003:f6:af2d:8700:b4c2:d356:c3fa:fe63]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43783d34657sm6448511f8f.6.2026.02.11.07.31.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Feb 2026 07:31:00 -0800 (PST) From: Sebastian Ott To: Peter Maydell , Paolo Bonzini , Eric Auger Cc: qemu-arm@nongnu.org, qemu-devel@nongnu.org, kvm@vger.kernel.org, kvmarm@lists.linux.dev, Sebastian Ott Subject: [PATCH v5 2/2] target/arm/kvm: add kvm-psci-version vcpu property Date: Wed, 11 Feb 2026 16:30:32 +0100 Message-ID: <20260211153032.19327-3-sebott@redhat.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260211153032.19327-1-sebott@redhat.com> References: <20260211153032.19327-1-sebott@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: zuQLiz4ApjW0crFJWYv0YFErnCskTWzzjPaDb0wSgtM_1770823862 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true 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.h | 6 +++ target/arm/kvm.c | 65 +++++++++++++++++++++++++++++++- 3 files changed, 81 insertions(+), 1 deletion(-) diff --git a/docs/system/arm/cpu-features.rst b/docs/system/arm/cpu-features.rst index 37d5dfd15b..50b106f2eb 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.h b/target/arm/cpu.h index e146f7e6c4..d3cfd444e8 100644 --- a/target/arm/cpu.h +++ b/target/arm/cpu.h @@ -1036,6 +1036,12 @@ struct ArchCPU { bool kvm_vtime_dirty; uint64_t kvm_vtime; + /* + * Intermediate value used during property parsing. + * Once finalized, the value should be read from psci_version. + */ + uint32_t kvm_prop_psci_version; + /* KVM steal time */ OnOffAuto kvm_steal_time; diff --git a/target/arm/kvm.c b/target/arm/kvm.c index ded582e0da..6d13cb4f3c 100644 --- a/target/arm/kvm.c +++ b/target/arm/kvm.c @@ -485,6 +485,46 @@ 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; } +typedef struct PSCIVersion { + uint32_t number; + const char *str; +} PSCIVersion; + +static const PSCIVersion 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" }, +}; + +static char *kvm_get_psci_version(Object *obj, Error **errp) +{ + ARMCPU *cpu = ARM_CPU(obj); + + for (int i = 0; i < ARRAY_SIZE(psci_versions); i++) { + if (psci_versions[i].number == cpu->psci_version) + return g_strdup(psci_versions[i].str); + } + + return g_strdup_printf("Unknown PSCI-version: %x", cpu->psci_version); +} + +static void kvm_set_psci_version(Object *obj, const char *value, Error **errp) +{ + ARMCPU *cpu = ARM_CPU(obj); + + for (int i = 0; i < ARRAY_SIZE(psci_versions); i++) { + if (!strcmp(value, psci_versions[i].str)) { + cpu->kvm_prop_psci_version = psci_versions[i].number; + return; + } + } + + error_setg(errp, "Invalid PSCI version."); +} + /* KVM VCPU properties should be prefixed with "kvm-". */ void kvm_arm_add_vcpu_properties(ARMCPU *cpu) { @@ -506,6 +546,12 @@ 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) @@ -1976,7 +2022,12 @@ 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)) { + if (cpu->kvm_prop_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->psci_version = QEMU_PSCI_VERSION_0_2; cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PSCI_0_2; } @@ -2015,6 +2066,18 @@ int kvm_arch_init_vcpu(CPUState *cs) } } + if (cpu->kvm_prop_psci_version) { + psciver = cpu->kvm_prop_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