Re: [PATCH 2/8] iommu/arm-smmu-v3: Use S2FWB when available

[Jason Gunthorpe <jgg@nvidia.com>]

On Thu, Aug 15, 2024 at 04:14:22PM +0000, Shameerali Kolothum Thodi wrote:
> > On Fri, Aug 09, 2024 at 02:26:13PM +0000, Shameerali Kolothum Thodi wrote:
> > > > +		if (smmu->features & ARM_SMMU_FEAT_S2FWB)
> > > > +			pgtbl_cfg.quirks |= IO_PGTABLE_QUIRK_ARM_S2FWB;
> > >
> > > This probably requires an update in arm_64_lpae_alloc_pgtable_s2() quirks
> > check.
> > 
> > Yep, fixed I was hoping you had HW to test this..
> 
> Let me see if I can get hold of a test setup that supports S2FWB.

Thanks!
 
> I do have another concern with respect to the hardware we have which doesn't
> support S2FWB, but those can claim CANWBS. The problem is, BIOS update is not
> a very liked/feasible solution to already deployed ones. But we can probably add 
> an option/quirk in SMMUv3 driver for those platforms(based on 
> ACPI_IORT_SMMU_V3_HISILICON_HI161X).  I hope this is fine.

I don't have an issue with doing that, if you can reliably identify
the platform in some way a kernel quirk seems reasonable.

Thanks,
Jason