backends/iommufd: Introduce iommufd_backend_alloc_veventq

Add a new helper for IOMMU_VEVENTQ_ALLOC ioctl to allocate a virtual event
queue (vEVENTQ) for a vIOMMU object.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
Message-id: 20260226084456.112142-2-skolothumtho@nvidia.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

backends/iommufd.c

@@ -504,6 +504,37 @@ bool iommufd_backend_alloc_vdev(IOMMUFDBackend *be, uint32_t dev_id,
     return true;
 }
 
+bool iommufd_backend_alloc_veventq(IOMMUFDBackend *be, uint32_t viommu_id,
+                                   uint32_t type, uint32_t depth,
+                                   uint32_t *out_veventq_id,
+                                   uint32_t *out_veventq_fd, Error **errp)
+{
+    int ret;
+    struct iommu_veventq_alloc alloc_veventq = {
+        .size = sizeof(alloc_veventq),
+        .flags = 0,
+        .type = type,
+        .veventq_depth = depth,
+        .viommu_id = viommu_id,
+    };
+
+    ret = ioctl(be->fd, IOMMU_VEVENTQ_ALLOC, &alloc_veventq);
+
+    trace_iommufd_viommu_alloc_eventq(be->fd, viommu_id, type,
+                                      alloc_veventq.out_veventq_id,
+                                      alloc_veventq.out_veventq_fd, ret);
+    if (ret) {
+        error_setg_errno(errp, errno, "IOMMU_VEVENTQ_ALLOC failed");
+        return false;
+    }
+
+    g_assert(out_veventq_id);
+    g_assert(out_veventq_fd);
+    *out_veventq_id = alloc_veventq.out_veventq_id;
+    *out_veventq_fd = alloc_veventq.out_veventq_fd;
+    return true;
+}
+
 bool host_iommu_device_iommufd_attach_hwpt(HostIOMMUDeviceIOMMUFD *idev,
                                            uint32_t hwpt_id, Error **errp)
 {

backends/trace-events

@@ -23,6 +23,7 @@ iommufd_backend_get_dirty_bitmap(int iommufd, uint32_t hwpt_id, uint64_t iova, u
 iommufd_backend_invalidate_cache(int iommufd, uint32_t id, uint32_t data_type, uint32_t entry_len, uint32_t entry_num, uint32_t done_num, uint64_t data_ptr, int ret) " iommufd=%d id=%u data_type=%u entry_len=%u entry_num=%u done_num=%u data_ptr=0x%"PRIx64" (%d)"
 iommufd_backend_alloc_viommu(int iommufd, uint32_t dev_id, uint32_t type, uint32_t hwpt_id, uint32_t viommu_id, int ret) " iommufd=%d type=%u dev_id=%u hwpt_id=%u viommu_id=%u (%d)"
 iommufd_backend_alloc_vdev(int iommufd, uint32_t dev_id, uint32_t viommu_id, uint64_t virt_id, uint32_t vdev_id, int ret) " iommufd=%d dev_id=%u viommu_id=%u virt_id=0x%"PRIx64" vdev_id=%u (%d)"
+iommufd_viommu_alloc_eventq(int iommufd, uint32_t viommu_id, uint32_t type, uint32_t veventq_id, uint32_t veventq_fd, int ret) " iommufd=%d viommu_id=%u type=%u veventq_id=%u veventq_fd=%u (%d)"
 
 # igvm-cfg.c
 igvm_reset_enter(int type) "type=%u"

include/system/iommufd.h

@@ -56,6 +56,15 @@ typedef struct IOMMUFDVdev {
     uint32_t virt_id;  /* virtual device ID */
 } IOMMUFDVdev;
 
+/* Virtual event queue interface for a vIOMMU */
+typedef struct IOMMUFDVeventq {
+    IOMMUFDViommu *viommu;
+    uint32_t veventq_id;
+    uint32_t veventq_fd;
+    uint32_t last_event_seq; /* Sequence number of last processed event */
+    bool event_start; /* True after first valid event; cleared on overflow */
+} IOMMUFDVeventq;
+
 bool iommufd_backend_connect(IOMMUFDBackend *be, Error **errp);
 void iommufd_backend_disconnect(IOMMUFDBackend *be);
 
@@ -86,6 +95,11 @@ bool iommufd_backend_alloc_vdev(IOMMUFDBackend *be, uint32_t dev_id,
                                 uint32_t viommu_id, uint64_t virt_id,
                                 uint32_t *out_vdev_id, Error **errp);
 
+bool iommufd_backend_alloc_veventq(IOMMUFDBackend *be, uint32_t viommu_id,
+                                   uint32_t type, uint32_t depth,
+                                   uint32_t *out_veventq_id,
+                                   uint32_t *out_veventq_fd, Error **errp);
+
 bool iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
                                         bool start, Error **errp);
 bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,