vfio: Move vfio_get_info_dma_avail() into helpers.c

vfio_get_info_dma_avail() is a low level routine similar to the other
routines extracting capabilities from 'struct vfio_iommu_type1_info'.
It belongs to file "helpers.c".

Reviewed-by: John Levon <john.levon@nutanix.com>
Link: https://lore.kernel.org/qemu-devel/20250318095415.670319-17-clg@redhat.com
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Link: https://lore.kernel.org/qemu-devel/20250326075122.1299361-18-clg@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/hw/vfio/helpers.c b/hw/vfio/helpers.c
index 054ee6e31e..1a584ba5f0 100644
--- a/hw/vfio/helpers.c
+++ b/hw/vfio/helpers.c
@@ -222,6 +222,37 @@ retry:
     return 0;
 }
 
+struct vfio_info_cap_header *
+vfio_get_iommu_type1_info_cap(struct vfio_iommu_type1_info *info, uint16_t id)
+{
+    if (!(info->flags & VFIO_IOMMU_INFO_CAPS)) {
+        return NULL;
+    }
+
+    return vfio_get_cap((void *)info, info->cap_offset, id);
+}
+
+bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
+                             unsigned int *avail)
+{
+    struct vfio_info_cap_header *hdr;
+    struct vfio_iommu_type1_info_dma_avail *cap;
+
+    /* If the capability cannot be found, assume no DMA limiting */
+    hdr = vfio_get_iommu_type1_info_cap(info,
+                                        VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);
+    if (!hdr) {
+        return false;
+    }
+
+    if (avail != NULL) {
+        cap = (void *) hdr;
+        *avail = cap->avail;
+    }
+
+    return true;
+}
+
 int vfio_get_dev_region_info(VFIODevice *vbasedev, uint32_t type,
                              uint32_t subtype, struct vfio_region_info **info)
 {