Re: [PATCH v6 30/33] backends/iommufd: Retrieve PASID width from iommufd_backend_get_device_info()

[Cédric Le Goater]

On 11/20/25 14:22, Shameer Kolothum wrote:

Retrieve PASID width from iommufd_backend_get_device_info() and store it
in HostIOMMUDeviceCaps for later use.

Reviewed-by: Jonathan Cameron <jonathan.came...@huawei.com>
Reviewed-by: Eric Auger <eric.au...@redhat.com>
Tested-by: Zhangfei Gao <zhangfei....@linaro.org>
Signed-off-by: Shameer Kolothum <skolothum...@nvidia.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  backends/iommufd.c                 | 6 +++++-
  hw/arm/smmuv3-accel.c              | 3 ++-
  hw/vfio/iommufd.c                  | 7 +++++--
  include/system/host_iommu_device.h | 3 +++
  include/system/iommufd.h           | 3 ++-
  5 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/backends/iommufd.c b/backends/iommufd.c
index e68a2c934f..6381f9664b 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -388,7 +388,8 @@ bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be,

bool iommufd_backend_get_device_info(IOMMUFDBackend *be, uint32_t devid,

                                       uint32_t *type, void *data, uint32_t len,
-                                     uint64_t *caps, Error **errp)
+                                     uint64_t *caps, uint8_t *max_pasid_log2,
+                                     Error **errp)
  {
      struct iommu_hw_info info = {
          .size = sizeof(info),
@@ -407,6 +408,9 @@ bool iommufd_backend_get_device_info(IOMMUFDBackend *be, 
uint32_t devid,
      g_assert(caps);
      *caps = info.out_capabilities;

+ if (max_pasid_log2) {

+        *max_pasid_log2 = info.out_max_pasid_log2;
+    }
      return true;
  }

diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c

index 35a94c720a..254d29ee2d 100644
--- a/hw/arm/smmuv3-accel.c
+++ b/hw/arm/smmuv3-accel.c
@@ -113,7 +113,8 @@ smmuv3_accel_hw_compatible(SMMUv3State *s, 
HostIOMMUDeviceIOMMUFD *idev,
      uint64_t caps;

if (!iommufd_backend_get_device_info(idev->iommufd, idev->devid, &data_type,

-                                         &info, sizeof(info), &caps, errp)) {
+                                         &info, sizeof(info), &caps, NULL,
+                                         errp)) {
          return false;
      }

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c

index ca8a6b7029..bbe944d7cc 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -353,7 +353,8 @@ static bool iommufd_cdev_autodomains_get(VFIODevice 
*vbasedev,
       * instead.
       */
      if (!iommufd_backend_get_device_info(vbasedev->iommufd, vbasedev->devid,
-                                         &type, NULL, 0, &hw_caps, errp)) {
+                                         &type, NULL, 0, &hw_caps, NULL,
+                                         errp)) {
          return false;
      }

@@ -889,19 +890,21 @@ static bool hiod_iommufd_vfio_realize(HostIOMMUDevice *hiod, void *opaque,

      HostIOMMUDeviceCaps *caps = &hiod->caps;
      VendorCaps *vendor_caps = &caps->vendor_caps;
      enum iommu_hw_info_type type;
+    uint8_t max_pasid_log2;
      uint64_t hw_caps;

hiod->agent = opaque; if (!iommufd_backend_get_device_info(vdev->iommufd, vdev->devid, &type,

                                           vendor_caps, sizeof(*vendor_caps),
-                                         &hw_caps, errp)) {
+                                         &hw_caps, &max_pasid_log2, errp)) {
          return false;
      }

hiod->name = g_strdup(vdev->name);

      caps->type = type;
      caps->hw_caps = hw_caps;
+    caps->max_pasid_log2 = max_pasid_log2;

idev = HOST_IOMMU_DEVICE_IOMMUFD(hiod);

      idev->iommufd = vdev->iommufd;
diff --git a/include/system/host_iommu_device.h 
b/include/system/host_iommu_device.h
index ab849a4a82..bfb2b60478 100644
--- a/include/system/host_iommu_device.h
+++ b/include/system/host_iommu_device.h
@@ -30,6 +30,8 @@ typedef union VendorCaps {
   * @hw_caps: host platform IOMMU capabilities (e.g. on IOMMUFD this represents
   *           the @out_capabilities value returned from IOMMU_GET_HW_INFO 
ioctl)
   *
+ * @max_pasid_log2: width of PASIDs supported by host IOMMU device
+ *
   * @vendor_caps: host platform IOMMU vendor specific capabilities (e.g. on
   *               IOMMUFD this represents a user-space buffer filled by kernel
   *               with host IOMMU @type specific hardware information data)
@@ -37,6 +39,7 @@ typedef union VendorCaps {
  typedef struct HostIOMMUDeviceCaps {
      uint32_t type;
      uint64_t hw_caps;
+    uint8_t max_pasid_log2;
      VendorCaps vendor_caps;
  } HostIOMMUDeviceCaps;
  #endif
diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index 41e216c677..aa78bf1e1d 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -71,7 +71,8 @@ int iommufd_backend_unmap_dma(IOMMUFDBackend *be, uint32_t 
ioas_id,
                                hwaddr iova, uint64_t size);
  bool iommufd_backend_get_device_info(IOMMUFDBackend *be, uint32_t devid,
                                       uint32_t *type, void *data, uint32_t len,
-                                     uint64_t *caps, Error **errp);
+                                     uint64_t *caps, uint8_t *max_pasid_log2,
+                                     Error **errp);
  bool iommufd_backend_alloc_hwpt(IOMMUFDBackend *be, uint32_t dev_id,
                                  uint32_t pt_id, uint32_t flags,
                                  uint32_t data_type, uint32_t data_len,