Re: [PATCH v4 24/27] backends/iommufd: Retrieve PASID width from iommufd_backend_get_device_info()

[Eric Auger <eric.auger@redhat.com>]

On 9/29/25 3:36 PM, Shameer Kolothum wrote:
> And store it in HostIOMMUDeviceCaps for later use.
>
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
> ---
>  backends/iommufd.c                 | 6 +++++-
>  hw/arm/smmuv3-accel.c              | 3 ++-
>  hw/vfio/iommufd.c                  | 7 +++++--
>  include/system/host_iommu_device.h | 2 ++
>  include/system/iommufd.h           | 3 ++-
>  5 files changed, 16 insertions(+), 5 deletions(-)
>
> diff --git a/backends/iommufd.c b/backends/iommufd.c
> index d3029d4658..023e67bc46 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 *pasid_log2,
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 (pasid_log2) {
> +        *pasid_log2 = info.out_max_pasid_log2;
> +    }
>      return true;
>  }
>  
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index ba37d690ad..283d36e6cd 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -124,7 +124,8 @@ 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 525df30ed1..89aa1b76a8 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -366,7 +366,8 @@ 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;
>      }
>  
> @@ -901,19 +902,21 @@ 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 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, &pasid_log2, errp)) {
>          return false;
>      }
>  
>      hiod->name = g_strdup(vdev->name);
>      caps->type = type;
>      caps->hw_caps = hw_caps;
> +    caps->max_pasid_log2 = 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..c6a2a3899a 100644
> --- a/include/system/host_iommu_device.h
> +++ b/include/system/host_iommu_device.h
> @@ -29,6 +29,7 @@ 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
> @@ -37,6 +38,7 @@ 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 e852193f35..d3efcffc45 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, ram_addr_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 *pasid_log2,
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,
Besides
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric