Re: [PATCH v4 0/3] KVM: arm64: ID register finalisation fixes

[Oliver Upton <oupton@kernel.org>]

Hi,

On Tue, Sep 29, 2026 at 12:57:57PM +0100, Mark Brown wrote:
> While looking at some feature enablement I noticed that there are some
> scenarios where we can end up with an inconsistently configured vCPU due
> to finalizing configuration based on ID registers before we have blocked
> writes to the ID registers. This series aims to clean up these issues.
> 
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> Changes in v4:
> - Rebase onto v7.3-rc3.
> - Add a lockdep assert.
> - Update Fuad's LLM tag.
> - Link to v3: https://patch.msgid.link/20260901-kvm-arm64-idreg-final-v3-0-a0ffa06fa872@kernel.org
> 
> Changes in v3:
> - Rebase onto v7.3-rc1.
> - Explain why KVM_ARCH_FLAG_ID_REGS_INITIALIZED is not reused.
> - Pull in Fuad's test cases.
> - Link to v2: https://patch.msgid.link/20260803-kvm-arm64-idreg-final-v2-0-d7d7e4efc640@kernel.org
> 
> Changes in v2:
> - Also replace the kvm_vm_has_ran_once() usage in kvm_set_vm_id_rg() and
>   kvm_vm_finalize_sys_regs() with kvm_id_regs_final().
> - Link to v1: https://patch.msgid.link/20260731-kvm-arm64-idreg-final-v1-0-3de2a5616dc6@kernel.org
> 
> ---
> Fuad Tabba (1):
>       KVM: arm64: selftests: Check ID regs are immutable after a failed run
> 
> Mark Brown (2):
>       KVM: arm64: Finalize guest-wide sysregs prior to per-vCPU sysregs
>       KVM: arm64: Block ID register changes after we rely on the values

I'm not too terribly jazzed about testing the relative ordering of
errors in the selftest, but I see why we need to do it. Otherwise,
everything looks good.

Reviewed-by: Oliver Upton <oupton@kernel.org>

Thanks,
Oliver