On Tue, 24 Feb 2026, Peter Maydell wrote:
On Fri, 20 Feb 2026 at 11:57, Sebastian Ott <[email protected]> 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
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 <[email protected]>
Tested-by: Eric Auger <[email protected]>
Signed-off-by: Sebastian Ott <[email protected]>
---
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) {
%hd is a signed value, so this will accept "-3.-5" I think ?
Probably we want %hu.
Ugh, right.
(If you agree I can just make this fix locally, no need for you to respin.)
That'd be great, Thanks!
Sebastian
