[PATCH] iommu/arm-smmu-v3: Add missing S2FWB feature detection

[Will Deacon]

On Tue, Apr 08, 2025 at 09:09:19AM -0300, Jason Gunthorpe wrote:
> On Tue, Apr 08, 2025 at 09:03:51AM +0530, Aneesh Kumar K.V (Arm) wrote:
> > Commit 67e4fe398513 ("iommu/arm-smmu-v3: Use S2FWB for NESTED domains")
> > introduced S2FWB usage but omitted the corresponding feature detection.
> > As a result, vIOMMU allocation fails on FVP in arm_vsmmu_alloc(), due to
> > the following check:
> > 
> > 	if (!arm_smmu_master_canwbs(master) &&
> > 	    !(smmu->features & ARM_SMMU_FEAT_S2FWB))
> > 		return ERR_PTR(-EOPNOTSUPP);
> > 
> > This patch adds the missing detection logic to prevent allocation
> > failure when S2FWB is supported.
> > 
> > Fixes: 67e4fe398513 ("iommu/arm-smmu-v3: Use S2FWB for NESTED domains")
> > Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar at kernel.org>
> > ---
> >  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 2 ++
> >  1 file changed, 2 insertions(+)
> 
> Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
> 
> This should go to rc

Yup. I'll pick this up next week along with any other SMMU fixes kicking
around.

Cheers,

Will