Re: [PATCH v2 7/8] iommu/arm-smmu-v3: Implement IOMMU_HWPT_ALLOC_NEST_PARENT

[Mostafa Saleh <smostafa@google.com>]

On Fri, Aug 30, 2024 at 02:18:17PM -0300, Jason Gunthorpe wrote:
> On Fri, Aug 30, 2024 at 03:27:00PM +0000, Mostafa Saleh wrote:
> > Hi Jason,
> > 
> > On Tue, Aug 27, 2024 at 12:51:37PM -0300, Jason Gunthorpe wrote:
> > > For SMMUv3 the parent must be a S2 domain, which can be composed
> > > into a IOMMU_DOMAIN_NESTED.
> > > 
> > > In future the S2 parent will also need a VMID linked to the VIOMMU and
> > > even to KVM.
> > > 
> > > Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> > > ---
> > >  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 11 ++++++++++-
> > >  1 file changed, 10 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > > index ec2fcdd4523a26..8db3db6328f8b7 100644
> > > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > > @@ -3103,7 +3103,8 @@ arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
> > >  			   const struct iommu_user_data *user_data)
> > >  {
> > >  	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> > > -	const u32 PAGING_FLAGS = IOMMU_HWPT_ALLOC_DIRTY_TRACKING;
> > > +	const u32 PAGING_FLAGS = IOMMU_HWPT_ALLOC_DIRTY_TRACKING |
> > > +				 IOMMU_HWPT_ALLOC_NEST_PARENT;
> > >  	struct arm_smmu_domain *smmu_domain;
> > >  	int ret;
> > >  
> > > @@ -3116,6 +3117,14 @@ arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
> > >  	if (!smmu_domain)
> > >  		return ERR_PTR(-ENOMEM);
> > >  
> > > +	if (flags & IOMMU_HWPT_ALLOC_NEST_PARENT) {
> > > +		if (!(master->smmu->features & ARM_SMMU_FEAT_NESTING)) {
> > > +			ret = -EOPNOTSUPP;
> > I think that should be:
> > 	ret = ERR_PTR(-EOPNOTSUPP);
> 
> Read again :)

Oops, sorry about the noise.

Thanks,
Mostafa
> 
> static struct iommu_domain *
> arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
> 			   struct iommu_domain *parent,
> 			   const struct iommu_user_data *user_data)
> {
> 	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> 	const u32 PAGING_FLAGS = IOMMU_HWPT_ALLOC_DIRTY_TRACKING |
> 				 IOMMU_HWPT_ALLOC_NEST_PARENT;
> 	struct arm_smmu_domain *smmu_domain;
> 	int ret;
>      ^^^^^^^^^^^^^^
> 
> err_free:
> 	kfree(smmu_domain);
> 	return ERR_PTR(ret);
>            ^^^^^^^^^^^^^^^^^^
> 
> Jason