Aside from the IOPF framework, iommufd provides an additional pathway to
report a hardware event or IRQ, via the VIRQ of VIOMMU infrastructure.

Implement the set/unset_vdev_id viommu ops, to take control of vdev_id's
lifecycle. Lock it properly so the threaded IRQ handler can read out the
viommu pointer and the virtual SID, to call iommufd_viommu_report_irq().

Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 109 +++++++++++++++-----
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |   2 +
 include/uapi/linux/iommufd.h                |  14 +++
 3 files changed, 97 insertions(+), 28 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c 
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index ad43351145d0..28daa0b253c6 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1810,6 +1810,7 @@ static int arm_smmu_handle_evt(struct arm_smmu_device 
*smmu, u64 *evt)
 {
        int ret = 0;
        u32 perm = 0;
+       struct iommu_domain *domain;
        struct arm_smmu_master *master;
        bool ssid_valid = evt[0] & EVTQ_0_SSV;
        u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
@@ -1830,41 +1831,59 @@ static int arm_smmu_handle_evt(struct arm_smmu_device 
*smmu, u64 *evt)
        if (evt[1] & EVTQ_1_S2)
                return -EFAULT;
 
-       if (!(evt[1] & EVTQ_1_STALL))
-               return -EOPNOTSUPP;
-
-       if (evt[1] & EVTQ_1_RnW)
-               perm |= IOMMU_FAULT_PERM_READ;
-       else
-               perm |= IOMMU_FAULT_PERM_WRITE;
-
-       if (evt[1] & EVTQ_1_InD)
-               perm |= IOMMU_FAULT_PERM_EXEC;
-
-       if (evt[1] & EVTQ_1_PnU)
-               perm |= IOMMU_FAULT_PERM_PRIV;
-
-       flt->type = IOMMU_FAULT_PAGE_REQ;
-       flt->prm = (struct iommu_fault_page_request) {
-               .flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
-               .grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
-               .perm = perm,
-               .addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
-       };
-
-       if (ssid_valid) {
-               flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
-               flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
-       }
-
        mutex_lock(&smmu->streams_mutex);
        master = arm_smmu_find_master(smmu, sid);
        if (!master) {
                ret = -EINVAL;
                goto out_unlock;
        }
+       domain = iommu_get_domain_for_dev(master->dev);
+
+       if (evt[1] & EVTQ_1_STALL) {
+               if (evt[1] & EVTQ_1_RnW)
+                       perm |= IOMMU_FAULT_PERM_READ;
+               else
+                       perm |= IOMMU_FAULT_PERM_WRITE;
+
+               if (evt[1] & EVTQ_1_InD)
+                       perm |= IOMMU_FAULT_PERM_EXEC;
+
+               if (evt[1] & EVTQ_1_PnU)
+                       perm |= IOMMU_FAULT_PERM_PRIV;
+
+               flt->type = IOMMU_FAULT_PAGE_REQ;
+               flt->prm = (struct iommu_fault_page_request) {
+                       .flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
+                       .grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
+                       .perm = perm,
+                       .addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
+               };
+
+               if (ssid_valid) {
+                       flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
+                       flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
+               }
+
+               iommu_report_device_fault(master->dev, &fault_evt);
+       } else if (domain && domain->type == IOMMU_DOMAIN_NESTED) {
+               mutex_lock(&master->lock);
+               if (master->vdev_id) {
+                       struct iommu_virq_arm_smmuv3 virq_data =
+                               *(struct iommu_virq_arm_smmuv3 *)evt;
 
-       iommu_report_device_fault(master->dev, &fault_evt);
+                       virq_data.evt[0] &= ~EVTQ_0_SID;
+                       virq_data.evt[0] |=
+                               FIELD_PREP(EVTQ_0_SID, master->vdev_id->id);
+
+                       iommufd_viommu_report_irq(master->vdev_id->viommu,
+                                                 IOMMU_VIRQ_TYPE_ARM_SMMUV3,
+                                                 &virq_data, 
sizeof(virq_data));
+               }
+               mutex_unlock(&master->lock);
+       } else {
+               /* Unhandled events should be pinned */
+               ret = -EFAULT;
+       }
 out_unlock:
        mutex_unlock(&smmu->streams_mutex);
        return ret;
@@ -3750,6 +3769,7 @@ static struct iommu_device *arm_smmu_probe_device(struct 
device *dev)
 
        master->dev = dev;
        master->smmu = smmu;
+       mutex_init(&master->lock);
        dev_iommu_priv_set(dev, master);
 
        ret = arm_smmu_insert_master(smmu, master);
@@ -3802,6 +3822,7 @@ static void arm_smmu_release_device(struct device *dev)
        arm_smmu_remove_master(master);
        if (arm_smmu_cdtab_allocated(&master->cd_table))
                arm_smmu_free_cd_tables(master);
+       mutex_destroy(&master->lock);
        kfree(master);
 }
 
@@ -3937,6 +3958,36 @@ static int arm_smmu_def_domain_type(struct device *dev)
        return 0;
 }
 
+static struct iommufd_vdev_id *
+arm_smmu_viommu_set_vdev_id(struct iommufd_viommu *viommu, struct device *dev,
+                           u64 id)
+{
+       struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+       struct iommufd_vdev_id *vdev_id;
+
+       vdev_id = kzalloc(sizeof(*vdev_id), GFP_KERNEL);
+       if (!vdev_id)
+               return ERR_PTR(-ENOMEM);
+
+       mutex_lock(&master->lock);
+       master->vdev_id = vdev_id;
+       mutex_unlock(&master->lock);
+
+       return vdev_id;
+}
+
+static void arm_smmu_viommu_unset_vdev_id(struct iommufd_vdev_id *vdev_id)
+{
+       struct device *dev = iommufd_vdev_id_to_dev(vdev_id);
+       struct arm_smmu_master *master = dev_iommu_priv_get(dev);
+
+       mutex_lock(&master->lock);
+       master->vdev_id = NULL;
+       mutex_unlock(&master->lock);
+
+       /* IOMMUFD core frees the memory of vdev_id */
+}
+
 static int arm_smmu_viommu_cache_invalidate(struct iommufd_viommu *viommu,
                                            struct iommu_user_data_array *array)
 {
@@ -3977,6 +4028,8 @@ static struct iommu_ops arm_smmu_ops = {
                .iova_to_phys           = arm_smmu_iova_to_phys,
                .free                   = arm_smmu_domain_free_paging,
                .default_viommu_ops = &(const struct iommufd_viommu_ops) {
+                       .set_vdev_id = arm_smmu_viommu_set_vdev_id,
+                       .unset_vdev_id = arm_smmu_viommu_unset_vdev_id,
                        .cache_invalidate = arm_smmu_viommu_cache_invalidate,
                }
        }
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h 
b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 6930810b85cb..5d20a67683e6 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -788,6 +788,8 @@ struct arm_smmu_master {
        struct arm_smmu_device          *smmu;
        struct device                   *dev;
        struct arm_smmu_stream          *streams;
+       struct mutex                    lock;
+       struct iommufd_vdev_id          *vdev_id;
        /* Locked by the iommu core using the group mutex */
        struct arm_smmu_ctx_desc_cfg    cd_table;
        unsigned int                    num_streams;
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index f9ec07efed8d..1dc2c0b05af7 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -956,9 +956,23 @@ struct iommu_viommu_unset_vdev_id {
 /**
  * enum iommu_virq_type - Virtual IRQ Type
  * @IOMMU_VIRQ_TYPE_NONE: INVALID type
+ * @IOMMU_VIRQ_TYPE_ARM_SMMUV3: ARM SMMUv3 Virtual Event
  */
 enum iommu_virq_type {
        IOMMU_VIRQ_TYPE_NONE = 0,
+       IOMMU_VIRQ_TYPE_ARM_SMMUV3 = 1,
+};
+
+/**
+ * struct iommu_virq_arm_smmuv3 - ARM SMMUv3 Virtual IRQ
+ *                                (IOMMU_VIRQ_TYPE_ARM_SMMUV3)
+ * @evt: 256-bit ARM SMMUv3 Event record, little-endian.
+ *
+ * StreamID field reports a virtual device ID. To receive a virtual IRQ for a
+ * device, it must set its virtual device ID via IOMMU_VIOMMU_SET_VDEV_ID.
+ */
+struct iommu_virq_arm_smmuv3 {
+       __aligned_u64 evt[4];
 };
 
 /**
-- 
2.43.0


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