[Qemu-devel] [PATCH v14 13/22] vfio: Introduce common function to add capabilities

[Kirti Wankhede]

Vendor driver using mediated device framework should use
vfio_info_add_capability() to add capabilities.
Introduced this function to reduce code duplication in vendor drivers.

vfio_info_cap_shift() manipulated a data buffer to add an offset to each
element in a chain. This data buffer is documented in a uapi header.
Changing vfio_info_cap_shift symbol to be available to all drivers.

Signed-off-by: Kirti Wankhede <address@hidden>
Signed-off-by: Neo Jia <address@hidden>
Change-Id: I6fca329fa2291f37a2c859d0bc97574d9e2ce1a6
---
 drivers/vfio/vfio.c  | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 include/linux/vfio.h |  3 +++
 2 files changed, 62 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index c850ba324be2..82257cf30f52 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -1797,8 +1797,66 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, 
size_t offset)
        for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset)
                tmp->next += offset;
 }
-EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
+EXPORT_SYMBOL(vfio_info_cap_shift);
 
+static int sparse_mmap_cap(struct vfio_info_cap *caps, void *cap_type)
+{
+       struct vfio_info_cap_header *header;
+       struct vfio_region_info_cap_sparse_mmap *sparse_cap, *sparse = cap_type;
+       size_t size;
+
+       size = sizeof(*sparse) + sparse->nr_areas *  sizeof(*sparse->areas);
+       header = vfio_info_cap_add(caps, size,
+                                  VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
+       if (IS_ERR(header))
+               return PTR_ERR(header);
+
+       sparse_cap = container_of(header,
+                       struct vfio_region_info_cap_sparse_mmap, header);
+       sparse_cap->nr_areas = sparse->nr_areas;
+       memcpy(sparse_cap->areas, sparse->areas,
+              sparse->nr_areas * sizeof(*sparse->areas));
+       return 0;
+}
+
+static int region_type_cap(struct vfio_info_cap *caps, void *cap_type)
+{
+       struct vfio_info_cap_header *header;
+       struct vfio_region_info_cap_type *type_cap, *cap = cap_type;
+
+       header = vfio_info_cap_add(caps, sizeof(*cap),
+                                  VFIO_REGION_INFO_CAP_TYPE, 1);
+       if (IS_ERR(header))
+               return PTR_ERR(header);
+
+       type_cap = container_of(header, struct vfio_region_info_cap_type,
+                               header);
+       type_cap->type = cap->type;
+       type_cap->subtype = cap->subtype;
+       return 0;
+}
+
+int vfio_info_add_capability(struct vfio_info_cap *caps, int cap_type_id,
+                            void *cap_type)
+{
+       int ret = -EINVAL;
+
+       if (!cap_type)
+               return 0;
+
+       switch (cap_type_id) {
+       case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
+               ret = sparse_mmap_cap(caps, cap_type);
+               break;
+
+       case VFIO_REGION_INFO_CAP_TYPE:
+               ret = region_type_cap(caps, cap_type);
+               break;
+       }
+
+       return ret;
+}
+EXPORT_SYMBOL(vfio_info_add_capability);
 
 /*
  * Pin a set of guest PFNs and return their associated host PFNs for local
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 6ab13f7e2920..e26f7ccab564 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -126,6 +126,9 @@ extern struct vfio_info_cap_header *vfio_info_cap_add(
                struct vfio_info_cap *caps, size_t size, u16 id, u16 version);
 extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
 
+extern int vfio_info_add_capability(struct vfio_info_cap *caps,
+                                   int cap_type_id, void *cap_type);
+
 struct pci_dev;
 #ifdef CONFIG_EEH
 extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
-- 
2.7.0