Re: [PATCH v2] KVM: PPC: Book3S HV: Validate arch_compat against host compatibility mode

[Vaibhav Jain <vaibhav@linux.ibm.com>]

Amit Machhiwal <amachhiw@linux.ibm.com> writes:

<snip>
> Introduce a validation mechanism that detects unsupported arch_compat
> values early in the guest initialization path. When an unsupported
> arch_compat is requested (e.g., Power11 on a Power10 compatibility mode
> host), kvmppc_set_arch_compat() uses cpu_has_feature(CPU_FTR_P11_PVR) to
> detect the mismatch and sets arch_compat to PVR_ARCH_INVALID. This
> triggers kvmppc_sanity_check() to mark the vCPU as invalid by setting
> vcpu->arch.sane to false. On the next vCPU run, kvmppc_vcpu_run_hv()
> checks this flag and returns -EINVAL, preventing the guest from running
> with an invalid processor compatibility configuration.
>
> With this, when a Power11 arch_compat is requested on a Power10
> compatibility mode host, the guest fails early during boot with:
>
>   error: kvm run failed Invalid argument
>
<snip>
>
> Suggested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> Cc: stable@vger.kernel.org # v6.13+
> Signed-off-by: Amit Machhiwal <amachhiw@linux.ibm.com>

Thanks Amit for addressing the issue reported on v1. The v2 patch
changes look aligned to what we discussed offline. Hence,


Reviewed-by: Vaibhav Jain <vaibhav@linux.ibm.com>


-- 
Cheers
~ Vaibhav