Re: [RFC PATCH v6 08/35] HACK! KVM: arm64: Enable SPE virtualization only in VHE mode

[Leo Yan <leo.yan@arm.com>]

On Fri, Nov 14, 2025 at 04:06:49PM +0000, Alexandru Elisei wrote:
> For RFC only.
> 
> Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
> ---
>  arch/arm64/kvm/spe.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kvm/spe.c b/arch/arm64/kvm/spe.c
> index 7e38f7d9075b..101258b55053 100644
> --- a/arch/arm64/kvm/spe.c
> +++ b/arch/arm64/kvm/spe.c
> @@ -24,8 +24,8 @@ void kvm_host_spe_init(struct arm_spe_pmu *arm_spu)
>  {
>  	struct arm_spu_entry *entry;
>  
> -	/* TODO: pKVM support */
> -	if (is_protected_kvm_enabled())
> +	/* TODO: pKVM and nVHE support */
> +	if (is_protected_kvm_enabled() || !has_vhe())

I totally agree we should focus on VHE mode first.  But it is worth
considering if we can unify solution across different virtualization
modes.

Aside from register access and IRQ handling, buffer management is the
most complex part of this series, it would be useful to know whether
the change can support different modes.

Thanks,
Leo

P.S. an interesting question is whether we can reuse virtio-iommu or
DMA buffer allocation for SPE.  My understanding is the IOMMU would be
simpler case, as the page table allocation and mapping occur entirely
on the host side.