Re: [PATCH 1/2] KVM: arm64: Hide FEAT_LS64_ACCDATA from guests

[Siddharth Chintamaneni <sidchintamaneni@gmail.com>]

On Tue, Oct 27, 2026 at 02:48:29PM +0100, Arnd Bergmann wrote:
> On Sat, Oct 24, 2026, at 09:14, Fuad Tabba wrote:
> > On a host that runs at EL1 (nVHE or hVHE), this also requires
> > __init_el2_fgt to set nACCDATA_EL1 in HFGRTR_EL2 and HFGWTR_EL2, and
> > __init_el2_hcrx to set HCRX_EL2.EnAS0. Without them, the ACCDATA_EL1
> > access traps to EL2 and the hypervisor panics, and so does ST64BV0
> > once SCTLR_EL1.EnAS0 is set. Happy to write those and the KVM change
> > once you're ready to post this.
>
> Thanks for the offer, that part is definitely not my area.

Hi Arnd, Fuad,

We are preparing to post the Microsoft Smart Data Accelerator (SDA) VF
dmaengine driver for Microsoft Cobalt SoCs, which uses IOMMU SVA with
direct EL0 ST64BV0 portal submissions carrying the process PASID in
ACCDATA_EL1.

Now that Fuad's KVM guest FEAT_LS64_ACCDATA series is queued, are you
planning to post the host ST64BV0 SVA + EL2/KVM patches as a standalone
series soon?

Either way, we have Cobalt hardware with FEAT_LS64_ACCDATA available and
would be happy to test your patches on silicon, or help put together and
carry any remaining pieces alongside our driver series if you prefer.

Thanks,
Siddharth