Re: [PATCH v10 07/12] arm-smmu-v3/sva: Add SVA domain support

[Baolu Lu]

On 2022/7/23 22:20, Jason Gunthorpe wrote:
> On Tue, Jul 05, 2022 at 01:07:05PM +0800, Lu Baolu wrote:
> > Add support for SVA domain allocation and provide an SVA-specific
> > iommu_domain_ops.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> > Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
> > ---
> >   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  6 ++
> >   .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   | 69 +++++++++++++++++++
> >   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  3 +
> >   3 files changed, 78 insertions(+)
> >
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> > index d2ba86470c42..96399dd3a67a 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
> > @@ -758,6 +758,7 @@ struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm);
> >   void arm_smmu_sva_unbind(struct iommu_sva *handle);
> >   u32 arm_smmu_sva_get_pasid(struct iommu_sva *handle);
> >   void arm_smmu_sva_notifier_synchronize(void);
> > +struct iommu_domain *arm_smmu_sva_domain_alloc(void);
> >   #else /* CONFIG_ARM_SMMU_V3_SVA */
> >   static inline bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
> >   {
> > @@ -803,5 +804,10 @@ static inline u32 arm_smmu_sva_get_pasid(struct iommu_sva *handle)
> >   }
> >   
> >   static inline void arm_smmu_sva_notifier_synchronize(void) {}
> > +
> > +static inline struct iommu_domain *arm_smmu_sva_domain_alloc(void)
> > +{
> > +	return NULL;
> > +}
> >   #endif /* CONFIG_ARM_SMMU_V3_SVA */
> >   #endif /* _ARM_SMMU_V3_H */
> > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > index f155d406c5d5..fc4555dac5b4 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
> > @@ -549,3 +549,72 @@ void arm_smmu_sva_notifier_synchronize(void)
> >   	 */
> >   	mmu_notifier_synchronize();
> >   }
> > +
> > +static int arm_smmu_sva_set_dev_pasid(struct iommu_domain *domain,
> > +				      struct device *dev, ioasid_t id)
> > +{
> > +	int ret = 0;
> > +	struct mm_struct *mm;
> > +	struct iommu_sva *handle;
> > +
> > +	if (domain->type != IOMMU_DOMAIN_SVA)
> > +		return -EINVAL;
>
> Not needed, this function is only called from the sva ops, other
> domain types are impossible, we don't need sanity tests in drivers
>
> > +	mm = domain->mm;
> > +	if (WARN_ON(!mm))
> > +		return -ENODEV;
>
> Also guarenteed by core code, don't need sanity tests

Above two updated. Thanks!

> > +static void arm_smmu_sva_block_dev_pasid(struct iommu_domain *domain,
> > +					 struct device *dev, ioasid_t id)
> > +{
> > +	struct mm_struct *mm = domain->mm;
> > +	struct arm_smmu_bond *bond = NULL, *t;
> > +	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> > +
> > +	mutex_lock(&sva_lock);
> > +	list_for_each_entry(t, &master->bonds, list) {
> > +		if (t->mm == mm) {
> > +			bond = t;
> > +			break;
>
> This doesn't seem like what I would expect, the domain should be used
> at the key in these datastructures, not the mm..

Both Intel and arm-smmu-v3 SVA code have room to cleanup. I've discussed
this with Jean. We will cleanup and refactor the individual drivers in
separated series.

> > index ae8ec8df47c1..a30b252e2f95 100644
> > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
> > @@ -1999,6 +1999,9 @@ static struct iommu_domain *arm_smmu_domain_alloc(unsigned type)
> >   {
> >   	struct arm_smmu_domain *smmu_domain;
> >   
> > +	if (type == IOMMU_DOMAIN_SVA)
> > +		return arm_smmu_sva_domain_alloc();
>
> If no drivers are sharing any code with their other alloc paths perhaps we
> should have a dedicated op for SVA?

AFAICS, Robin is refactoring the domain allocation interfaces. How about
leaving this until we finalize the interface?

Best regards,
baolu