Re: [RFC PATCH v7 08/28] HACK! KVM: arm64: Disable SPE virtualization if protected KVM is enabled

["Lorenzo Stoakes (ARM)" <ljs@kernel.org>]

On Thu, Sep 03, 2026 at 05:06:03PM +0100, Alexandru Elisei wrote:
> For RFC only.
>

I realise this isn't intended for the final series :) but be good to put
something here briefly for reviewers to explain why this is here, e.g. pKVM
needs special attention etc. Similar comment for 9, 10 if there's an RFC
respin.

So for this and patches 9, 10 in general it seems you disable the feature
for:

- pKVM (at global level)
- non-VHE
- nested virt

Are these temporary for proof-of-concept reasons or do you plan to make
them permanent limitations for the initial implementation of SPE?

If the former it'd be good to know what your plans are to provide support
for these, if the latter it seems sensible to put these all in one patch
that describes why you are limiting each.

> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>

I won't bother actually reviewing the hacks, so just the queries above for
8, 9, 10. Will resume review at 11 :)

> ---
>  arch/arm64/kvm/spe.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
> index 646806a60d66..97160d1fae81 100644
> --- a/arch/arm64/kvm/spe.c
> +++ b/arch/arm64/kvm/spe.c
> @@ -22,6 +22,10 @@ void kvm_spe_add_instance(struct arm_spe_pmu *spe_pmu)
>  {
>  	struct spe_pmu_entry *entry;
>
> +	/* TODO: pKVM support */
> +	if (is_protected_kvm_enabled())
> +		return;
> +
>  	guard(mutex)(&spe_pmus_lock);
>
>  	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
> --
> 2.43.0
>
>

--
Cheers, Lorenzo