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

[Jason Gunthorpe]

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 at 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 :)

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