[PATCH v2 16/19] iommu/arm-smmu-v3: Add a global static BLOCKED domain

[Jason Gunthorpe]

On Wed, Nov 15, 2023 at 11:57:39PM +0800, Michael Shavit wrote:
> On Tue, Nov 14, 2023 at 1:53 AM Jason Gunthorpe <jgg at nvidia.com> wrote:
> >
> > Using the same design as the IDENTITY domain install an
> > STRTAB_STE_0_CFG_ABORT STE.
> >
> > Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
> Reviewed-by: Michael Shavit <mshavit at google.com>
> 
> Are there any subtle observable changes hidden here? IIUC the iommu
> framework would have previously installed an empty UNMANAGED domain
> but will now end up installing an abort STE instead.

I don't think meaningfully. The empty UNMANAGED domain is a fallback
for drivers that don't natively support BLOCKED. SMMUv3 already uses
ABORT for this use case in the pre-boot and unattached devices flows,
so if there is something wrong we have an existing issue already.

I suspect there are slight differences about what gets logged if a DMA
hits ABORT vs UNMANAGED, but not material.

Thanks,
Jason