On Thu, Mar 4, 2021 at 7:48 AM Robin Murphy [off-list ref] wrote:

On 2021-03-01 08:42, Christoph Hellwig wrote:

quoted

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.

quoted

---
  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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