On Mon, Jun 14, 2021 at 2:49 PM Shameerali Kolothum Thodi
[off-list ref] wrote:

quoted

quoted

-----Original Message-----
From: Robin Murphy [mailto:robin.murphy@arm.com]
Sent: 14 June 2021 12:23
To: Shameerali Kolothum Thodi <redacted>;
linux-arm-kernel@lists.infradead.org; linux-acpi@vger.kernel.org;
iommu@lists.linux-foundation.org
Cc: jon@solid-run.com; Linuxarm <redacted>;
steven.price@arm.com; Guohanjun (Hanjun Guo) [off-list ref];
yangyicong [off-list ref]; Sami.Mujawar@arm.com;
wanghuiqiang [off-list ref]
Subject: Re: [PATCH v5 3/8] ACPI/IORT: Add a helper to retrieve RMR memory
regions

On 2021-05-24 12:02, Shameer Kolothum wrote:

quoted

Add a helper function that retrieves RMR memory descriptors
associated with a given IOMMU. This will be used by IOMMU
drivers to setup necessary mappings.

Now that we have this, invoke it from the generic helper
interface.

Signed-off-by: Shameer Kolothum

[off-list ref]

quoted

---
  drivers/acpi/arm64/iort.c | 50

+++++++++++++++++++++++++++++++++++++++

quoted

  drivers/iommu/dma-iommu.c |  4 ++++
  include/linux/acpi_iort.h |  7 ++++++
  3 files changed, 61 insertions(+)

diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
index fea1ffaedf3b..01917caf58de 100644
--- a/drivers/acpi/arm64/iort.c
+++ b/drivers/acpi/arm64/iort.c

@@ -12,6 +12,7 @@

  #include <linux/acpi_iort.h>
  #include <linux/bitfield.h>
+#include <linux/dma-iommu.h>
  #include <linux/iommu.h>
  #include <linux/kernel.h>
  #include <linux/list.h>

@@ -837,6 +838,53 @@ static inline int iort_add_device_replay(struct

device *dev)

quoted

    return err;
  }

+/**
+ * iort_iommu_get_rmrs - Helper to retrieve RMR info associated with

IOMMU

quoted

+ * @iommu: fwnode for the IOMMU
+ * @head: RMR list head to be populated
+ *
+ * Returns: 0 on success, <0 failure
+ */
+int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
+                   struct list_head *head)
+{
+   struct iort_rmr_entry *e;
+   struct acpi_iort_node *iommu;
+   int rmrs = 0;
+
+   iommu = iort_get_iort_node(iommu_fwnode);
+   if (!iommu || list_empty(&iort_rmr_list))
+           return -ENODEV;
+
+   list_for_each_entry(e, &iort_rmr_list, list) {
+           int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_NOEXEC |

IOMMU_MMIO;

quoted

+           struct iommu_resv_region *region;
+           enum iommu_resv_type type;
+           struct acpi_iort_rmr_desc *rmr_desc;
+
+           if (e->smmu != iommu)
+                   continue;
+
+           rmr_desc = e->rmr_desc;
+           if (e->flags & IOMMU_RMR_REMAP_PERMITTED)
+                   type = IOMMU_RESV_DIRECT_RELAXABLE;
+           else
+                   type = IOMMU_RESV_DIRECT;

I have been looking at this a bit more and looking at the history of
RMR_REMAP_PERMITTED.  Based on the history I have found it
seems to me like this would be the better options for prot.

@@ -840,7 +840,7 @@ int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
                return -ENODEV;

        list_for_each_entry(e, &iort_rmr_list, list) {
-               int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
+               int prot = IOMMU_READ | IOMMU_WRITE;
                struct iommu_resv_region *region;
                enum iommu_resv_type type;
                struct acpi_iort_rmr_desc *rmr_desc;

@@ -849,10 +849,13 @@ int iort_iommu_get_rmrs(struct fwnode_handle

*iommu_fwnode,
                        continue;

                rmr_desc = e->rmr_desc;
-               if (e->flags & IOMMU_RMR_REMAP_PERMITTED)
+               if (e->flags & IOMMU_RMR_REMAP_PERMITTED) {
                        type = IOMMU_RESV_DIRECT_RELAXABLE;
-               else
+                       prot |= IOMMU_CACHE;
+               } else {
                        type = IOMMU_RESV_DIRECT;
+                       prot |= IOMMU_MMIO;
+               }

                region = iommu_alloc_resv_region(rmr_desc->base_address,
                                                 rmr_desc->length,

any input on this?  My reasoning is that IOMMU_RESV_DIRECT is specifically
referenced for things like MSI doorbell and in all the examples needs
IOMMU_MMIO, while REMAP_PERMITTED seems to be used for allocated
system memory that is then used for device specific reserved regions which
commits say would be like a GPU or USB device.

-Jon

quoted

quoted

Wasn't the idea that we can do all this during the initial parsing, i.e.
we don't even have iort_rmr_entry, we store them as iommu_resv_regions
and simply kmemdup() or whatever at this point?

Hmm... Not yet. I removed struct iommu_rmr() from v4. But yes, it looks like
we can get rid of iort_rmr_entry as well. Will give it a go in next.

Thanks,
Shameer

quoted

Robin.

quoted

+
+           region = iommu_alloc_resv_region(rmr_desc->base_address,
+                                            rmr_desc->length,
+                                            prot, type);
+           if (region) {
+                   region->fw_data.rmr.flags = e->flags;
+                   region->fw_data.rmr.sid = e->sid;
+                   list_add_tail(&region->list, head);
+                   rmrs++;
+           }
+   }
+
+   return (rmrs == 0) ? -ENODEV : 0;
+}
+
  /**
   * iort_iommu_msi_get_resv_regions - Reserved region driver helper
   * @dev: Device from iommu_get_resv_regions()

@@ -1108,6 +1156,8 @@ int iort_iommu_msi_get_resv_regions(struct

device *dev, struct list_head *head)

quoted

  const struct iommu_ops *iort_iommu_configure_id(struct device *dev,
                                            const u32 *input_id)
  { return NULL; }
+int iort_iommu_get_rmrs(struct fwnode_handle *fwnode, struct list_head

*head)

quoted

+{ return -ENODEV; }
  #endif

  static int nc_dma_get_range(struct device *dev, u64 *size)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 229ec65d98be..f893d460cfa4 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c

@@ -185,6 +185,9 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
  int iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode,
                   struct list_head *list)
  {
+   if (!is_of_node(iommu_fwnode))
+           return iort_iommu_get_rmrs(iommu_fwnode, list);
+
    return -EINVAL;
  }
  EXPORT_SYMBOL(iommu_dma_get_rmrs);

@@ -200,6 +203,7 @@ EXPORT_SYMBOL(iommu_dma_get_rmrs);
  void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
                    struct list_head *list)
  {
+   generic_iommu_put_resv_regions(iommu_fwnode->dev, list);
  }
  EXPORT_SYMBOL(iommu_dma_put_rmrs);

diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
index 1a12baa58e40..e8c45fa59531 100644
--- a/include/linux/acpi_iort.h
+++ b/include/linux/acpi_iort.h

@@ -39,6 +39,8 @@ const struct iommu_ops

*iort_iommu_configure_id(struct device *dev,

quoted

                                            const u32 *id_in);
  int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head

*head);

quoted

  phys_addr_t acpi_iort_dma_get_max_cpu_address(void);
+int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
+                   struct list_head *list);
  #else
  static inline void acpi_iort_init(void) { }
  static inline u32 iort_msi_map_id(struct device *dev, u32 id)

@@ -59,6 +61,11 @@ int iort_iommu_msi_get_resv_regions(struct device

*dev, struct list_head *head)

quoted

  static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)
  { return PHYS_ADDR_MAX; }
+
+static inline
+int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
+                   struct list_head *list)
+{ return -ENODEV; }
  #endif

  #endif /* __ACPI_IORT_H__ */