Re: [Freedreno] [PATCH 16/17] iommu: remove DOMAIN_ATTR_IO_PGTABLE_CFG

[Rob Clark <robdclark@gmail.com>]

On Thu, Mar 4, 2021 at 7:48 AM Robin Murphy <robin.murphy@arm.com> wrote:
>
> On 2021-03-01 08:42, Christoph Hellwig wrote:
> > Signed-off-by: Christoph Hellwig <hch@lst.de>
>
> Moreso than the previous patch, where the feature is at least relatively
> generic (note that there's a bunch of in-flight development around
> DOMAIN_ATTR_NESTING), I'm really not convinced that it's beneficial to
> bloat the generic iommu_ops structure with private driver-specific
> interfaces. The attribute interface is a great compromise for these
> kinds of things, and you can easily add type-checked wrappers around it
> for external callers (maybe even make the actual attributes internal
> between the IOMMU core and drivers) if that's your concern.

I suppose if this is *just* for the GPU we could move it into adreno_smmu_priv..

But one thing I'm not sure about is whether
IO_PGTABLE_QUIRK_ARM_OUTER_WBWA is something that other devices
*should* be using as well, but just haven't gotten around to yet.

BR,
-R

> Robin.
>
> > ---
> >   drivers/gpu/drm/msm/adreno/adreno_gpu.c |  2 +-
> >   drivers/iommu/arm/arm-smmu/arm-smmu.c   | 40 +++++++------------------
> >   drivers/iommu/iommu.c                   |  9 ++++++
> >   include/linux/iommu.h                   |  9 +++++-
> >   4 files changed, 29 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > index 0f184c3dd9d9ec..78d98ab2ee3a68 100644
> > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> > @@ -191,7 +191,7 @@ void adreno_set_llc_attributes(struct iommu_domain *iommu)
> >       struct io_pgtable_domain_attr pgtbl_cfg;
> >
> >       pgtbl_cfg.quirks = IO_PGTABLE_QUIRK_ARM_OUTER_WBWA;
> > -     iommu_domain_set_attr(iommu, DOMAIN_ATTR_IO_PGTABLE_CFG, &pgtbl_cfg);
> > +     iommu_domain_set_pgtable_attr(iommu, &pgtbl_cfg);
> >   }
> >
> >   struct msm_gem_address_space *
> > diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > index 2e17d990d04481..2858999c86dfd1 100644
> > --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> > @@ -1515,40 +1515,22 @@ static int arm_smmu_domain_enable_nesting(struct iommu_domain *domain)
> >       return ret;
> >   }
> >
> > -static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
> > -                                 enum iommu_attr attr, void *data)
> > +static int arm_smmu_domain_set_pgtable_attr(struct iommu_domain *domain,
> > +             struct io_pgtable_domain_attr *pgtbl_cfg)
> >   {
> > -     int ret = 0;
> >       struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
> > +     int ret = -EPERM;
> >
> > -     mutex_lock(&smmu_domain->init_mutex);
> > -
> > -     switch(domain->type) {
> > -     case IOMMU_DOMAIN_UNMANAGED:
> > -             switch (attr) {
> > -             case DOMAIN_ATTR_IO_PGTABLE_CFG: {
> > -                     struct io_pgtable_domain_attr *pgtbl_cfg = data;
> > -
> > -                     if (smmu_domain->smmu) {
> > -                             ret = -EPERM;
> > -                             goto out_unlock;
> > -                     }
> > +     if (domain->type != IOMMU_DOMAIN_UNMANAGED)
> > +             return -EINVAL;
> >
> > -                     smmu_domain->pgtbl_cfg = *pgtbl_cfg;
> > -                     break;
> > -             }
> > -             default:
> > -                     ret = -ENODEV;
> > -             }
> > -             break;
> > -     case IOMMU_DOMAIN_DMA:
> > -             ret = -ENODEV;
> > -             break;
> > -     default:
> > -             ret = -EINVAL;
> > +     mutex_lock(&smmu_domain->init_mutex);
> > +     if (!smmu_domain->smmu) {
> > +             smmu_domain->pgtbl_cfg = *pgtbl_cfg;
> > +             ret = 0;
> >       }
> > -out_unlock:
> >       mutex_unlock(&smmu_domain->init_mutex);
> > +
> >       return ret;
> >   }
> >
> > @@ -1609,7 +1591,7 @@ static struct iommu_ops arm_smmu_ops = {
> >       .device_group           = arm_smmu_device_group,
> >       .dma_use_flush_queue    = arm_smmu_dma_use_flush_queue,
> >       .dma_enable_flush_queue = arm_smmu_dma_enable_flush_queue,
> > -     .domain_set_attr        = arm_smmu_domain_set_attr,
> > +     .domain_set_pgtable_attr = arm_smmu_domain_set_pgtable_attr,
> >       .domain_enable_nesting  = arm_smmu_domain_enable_nesting,
> >       .of_xlate               = arm_smmu_of_xlate,
> >       .get_resv_regions       = arm_smmu_get_resv_regions,
> > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> > index 2e9e058501a953..8490aefd4b41f8 100644
> > --- a/drivers/iommu/iommu.c
> > +++ b/drivers/iommu/iommu.c
> > @@ -2693,6 +2693,15 @@ int iommu_domain_enable_nesting(struct iommu_domain *domain)
> >   }
> >   EXPORT_SYMBOL_GPL(iommu_domain_enable_nesting);
> >
> > +int iommu_domain_set_pgtable_attr(struct iommu_domain *domain,
> > +             struct io_pgtable_domain_attr *pgtbl_cfg)
> > +{
> > +     if (!domain->ops->domain_set_pgtable_attr)
> > +             return -EINVAL;
> > +     return domain->ops->domain_set_pgtable_attr(domain, pgtbl_cfg);
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_domain_set_pgtable_attr);
> > +
> >   void iommu_get_resv_regions(struct device *dev, struct list_head *list)
> >   {
> >       const struct iommu_ops *ops = dev->bus->iommu_ops;
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index aed88aa3bd3edf..39d3ed4d2700ac 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -40,6 +40,7 @@ struct iommu_domain;
> >   struct notifier_block;
> >   struct iommu_sva;
> >   struct iommu_fault_event;
> > +struct io_pgtable_domain_attr;
> >
> >   /* iommu fault flags */
> >   #define IOMMU_FAULT_READ    0x0
> > @@ -107,7 +108,6 @@ enum iommu_cap {
> >    */
> >
> >   enum iommu_attr {
> > -     DOMAIN_ATTR_IO_PGTABLE_CFG,
> >       DOMAIN_ATTR_MAX,
> >   };
> >
> > @@ -196,6 +196,7 @@ struct iommu_iotlb_gather {
> >    * @dma_enable_flush_queue: Try to enable the DMA flush queue
> >    * @domain_set_attr: Change domain attributes
> >    * @domain_enable_nesting: Enable nesting
> > + * @domain_set_pgtable_attr: Set io page table attributes
> >    * @get_resv_regions: Request list of reserved regions for a device
> >    * @put_resv_regions: Free list of reserved regions for a device
> >    * @apply_resv_region: Temporary helper call-back for iova reserved ranges
> > @@ -249,6 +250,8 @@ struct iommu_ops {
> >       int (*domain_set_attr)(struct iommu_domain *domain,
> >                              enum iommu_attr attr, void *data);
> >       int (*domain_enable_nesting)(struct iommu_domain *domain);
> > +     int (*domain_set_pgtable_attr)(struct iommu_domain *domain,
> > +                     struct io_pgtable_domain_attr *pgtbl_cfg);
> >
> >       /* Request/Free a list of reserved regions for a device */
> >       void (*get_resv_regions)(struct device *dev, struct list_head *list);
> > @@ -493,9 +496,13 @@ extern int iommu_group_id(struct iommu_group *group);
> >   extern struct iommu_domain *iommu_group_default_domain(struct iommu_group *);
> >
> >   bool iommu_dma_use_flush_queue(struct iommu_domain *domain);
> > +int iommu_domain_set_pgtable_attr(struct iommu_domain *domain,
> > +             struct io_pgtable_domain_attr *pgtbl_cfg);
> >   extern int iommu_domain_set_attr(struct iommu_domain *domain, enum iommu_attr,
> >                                void *data);
> >   int iommu_domain_enable_nesting(struct iommu_domain *domain);
> > +int iommu_domain_set_pgtable_attr(struct iommu_domain *domain,
> > +             struct io_pgtable_domain_attr *pgtbl_cfg);
> >
> >   extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
> >                             unsigned long iova, int flags);
> >
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