Re: [PATCH v4 0/2] arm: add kvm-psci-version vcpu property

[Eric Auger <eric.auger@redhat.com>]

Hi Sebastian,

On 12/2/25 5:08 PM, Sebastian Ott wrote:
> This series adds a vcpu knob to request a specific PSCI version
> from KVM via the KVM_REG_ARM_PSCI_VERSION FW register.
>
> The use case for this is to support migration between host kernels
> that differ in their default (a.k.a. most recent) PSCI version.
>
> Note: in order to support PSCI v0.1 we need to drop vcpu
> initialization with KVM_CAP_ARM_PSCI_0_2 in that case.
> Alternatively we could limit support to versions >=0.2 .
>
> Changes since V3 [3]:
> * changed variable name as requested by Eric
> * added R-B
> Changes since V2 [2]:
> * fix kvm_get_psci_version() when the prop is not specified - thanks Eric!
> * removed the assertion in kvm_get_psci_version() so that this also works
>   with a future kernel/psci version
> * added R-B
> Changes since V1 [1]:
> * incorporated feedback from Peter and Eric
>
> [1] https://lore.kernel.org/kvmarm/20250911144923.24259-1-sebott@redhat.com/
> [2] https://lore.kernel.org/kvmarm/20251030165905.73295-1-sebott@redhat.com/
> [3] https://lore.kernel.org/kvmarm/20251112181357.38999-1-sebott@redhat.com/
>
> Sebastian Ott (2):
>   target/arm/kvm: add constants for new PSCI versions
>   target/arm/kvm: add kvm-psci-version vcpu property
>
>  docs/system/arm/cpu-features.rst |  5 +++
>  target/arm/cpu.h                 |  6 +++
>  target/arm/kvm-consts.h          |  2 +
>  target/arm/kvm.c                 | 64 +++++++++++++++++++++++++++++++-
>  4 files changed, 76 insertions(+), 1 deletion(-)
>
Feel free to add my
Tested-by: Eric Auger <eric.auger@redhat.com>

I was able to migrate from a host featuring "KVM: arm64: Add support for
PSCI v1.2 and v1.3" to an "old" one that doesn't using
,kvm-psci-version=1.1

Thanks

Eric