backends/iommufd: Add get_pasid_info() callback

The get_pasid_info callback retrieves PASID capability information
when the HostIOMMUDevice backend supports it. Currently, only the
Linux IOMMUFD backend provides this information.

This will be used by a subsequent patch to synthesize a PASID
capability for vfio-pci devices behind a vIOMMU that supports PASID.

Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Reviewed-by: Yi Liu <yi.l.liu@intel.com>
Message-id: 20260126104342.253965-34-skolothumtho@nvidia.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

backends/iommufd.c

@@ -539,11 +539,28 @@ static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp)
     }
 }
 
+static bool hiod_iommufd_get_pasid_info(HostIOMMUDevice *hiod,
+                                        PasidInfo *pasid_info)
+{
+    HostIOMMUDeviceCaps *caps = &hiod->caps;
+
+    if (!caps->max_pasid_log2) {
+        return false;
+    }
+
+    g_assert(pasid_info);
+    pasid_info->exec_perm = (caps->hw_caps & IOMMU_HW_CAP_PCI_PASID_EXEC);
+    pasid_info->priv_mod = (caps->hw_caps & IOMMU_HW_CAP_PCI_PASID_PRIV);
+    pasid_info->max_pasid_log2 = caps->max_pasid_log2;
+    return true;
+}
+
 static void hiod_iommufd_class_init(ObjectClass *oc, const void *data)
 {
     HostIOMMUDeviceClass *hioc = HOST_IOMMU_DEVICE_CLASS(oc);
 
     hioc->get_cap = hiod_iommufd_get_cap;
+    hioc->get_pasid_info = hiod_iommufd_get_pasid_info;
 };
 
 static const TypeInfo types[] = {

include/system/host_iommu_device.h

@@ -59,6 +59,12 @@ struct HostIOMMUDevice {
 #endif
 };
 
+typedef struct PasidInfo {
+    bool exec_perm;
+    bool priv_mod;
+    uint8_t max_pasid_log2;
+} PasidInfo;
+
 /**
  * struct HostIOMMUDeviceClass - The base class for all host IOMMU devices.
  *
@@ -116,6 +122,17 @@ struct HostIOMMUDeviceClass {
      * @hiod: handle to the host IOMMU device
      */
     uint64_t (*get_page_size_mask)(HostIOMMUDevice *hiod);
+    /**
+     * @get_pasid_info: Return the PASID information associated with the
+     * @hiod Host IOMMU device.
+     *
+     * @hiod: handle to the host IOMMU device
+     *
+     * @pasid_info: If success, returns the PASID related information.
+     *
+     * Returns: true on success, false on failure.
+     */
+    bool (*get_pasid_info)(HostIOMMUDevice *hiod, PasidInfo *pasid_info);
 };
 
 /*