From: Gerd Hoffmann <kraxel@xxxxxxxxxx>
A blob resource is a container for:
- VIRTIO_GPU_BLOB_MEM_GUEST: a guest memory allocation
(referred to as a "guest-only blob resource")
- VIRTIO_GPU_BLOB_MEM_HOST3D: a host3d memory allocation
(referred to as a "host-only blob resource")
- VIRTIO_GPU_BLOB_MEM_HOST3D_GUEST: a guest + host3d memory allocation
(referred to as a "default blob resource").
The memory properties of the blob resource must be described by
`blob_mem`.
For default and guest only blob resources set, `nents` guest system
pages are assigned to the resource. For default blob resources,
these guest pages are used for transfer operations. Attach/detach is
also possible to allow swap-in/swap-out, but isn't required since it
may not be applicable to future blob mem types
(shared guest/guest vram).
Host allocations depend on whether the 3D is supported. If 3D is not
supported, the only valid field for `blob_mem` is
VIRTIO_GPU_BLOB_MEM_GUEST.
If 3D is supported, the virtio-gpu resource is created from the
context local object identified by the `blob_id`. The actual host
allocation done by the CMD_SUBMIT_3D.
Userspace must specify if the blob resource is intended to be used
for userspace mapping, sharing between virtio-gpu contexts and/or
sharing between virtio devices. This is done via `blob_flags`.
For 3D hosts, both VIRTIO_GPU_CMD_TRANSFER_TO_HOST_3D and
VIRTIO_GPU_CMD_TRANSFER_FROM_HOST_3D may be used to update
the host resource. There is no restriction on the image/buffer
view the guest/host userspace has on the blob resource.
VIRTIO_GPU_CMD_SET_SCANOUT_BLOB / VIRTIO_GPU_CMD_RESOURCE_FLUSH may
be used with blob resources as well. The modifier is intentionally
left out of SCANOUT_BLOB, and auxilary blobs are also left out
as a simplification.
The use case for blob resources is zero-copy, needed for coherent
memory in virglrenderer. Host only blob resources are not mappable
without the feature described in the next patch, but are shareable.
Future work:
- Emulated coherent `blob_mem` type for QEMU/vhost-user
- A `blob_mem` type for guest-only resources imported in
cache-coherent FOSS GPU/display drivers.
- Display integration involving the blob model using seamless
Wayland windows.
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Co-developed-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
Signed-off-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
Acked-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
Acked-by: Chia-I Wu <olvaffe@xxxxxxxxx>
Acked-by: Lingfeng Yang <lfy@xxxxxxxxxx>
Link: https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/374
---
include/uapi/linux/virtio_gpu.h | 43 +++++++++++++++++++++++++++++++++
1 file changed, 43 insertions(+)
diff --git a/include/uapi/linux/virtio_gpu.h b/include/uapi/linux/virtio_gpu.h
index 747a5c5cc4e60..4ddf2fe342ed0 100644
--- a/include/uapi/linux/virtio_gpu.h
+++ b/include/uapi/linux/virtio_gpu.h
@@ -55,6 +55,11 @@
*/
#define VIRTIO_GPU_F_RESOURCE_UUID 2
+/*
+ * VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB
+ */
+#define VIRTIO_GPU_F_RESOURCE_BLOB 3
+
enum virtio_gpu_ctrl_type {
VIRTIO_GPU_UNDEFINED = 0,
@@ -71,6 +76,8 @@ enum virtio_gpu_ctrl_type {
VIRTIO_GPU_CMD_GET_CAPSET,
VIRTIO_GPU_CMD_GET_EDID,
VIRTIO_GPU_CMD_RESOURCE_ASSIGN_UUID,
+ VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB,
+ VIRTIO_GPU_CMD_SET_SCANOUT_BLOB,
/* 3d commands */
VIRTIO_GPU_CMD_CTX_CREATE = 0x0200,
@@ -359,4 +366,40 @@ struct virtio_gpu_resp_resource_uuid {
__u8 uuid[16];
};
+/* VIRTIO_GPU_CMD_RESOURCE_CREATE_BLOB */
+struct virtio_gpu_resource_create_blob {
+ struct virtio_gpu_ctrl_hdr hdr;
+ __le32 resource_id;
+#define VIRTIO_GPU_BLOB_MEM_GUEST 0x0001
+#define VIRTIO_GPU_BLOB_MEM_HOST3D 0x0002
+#define VIRTIO_GPU_BLOB_MEM_HOST3D_GUEST 0x0003
+
+#define VIRTIO_GPU_BLOB_FLAG_USE_MAPPABLE 0x0001
+#define VIRTIO_GPU_BLOB_FLAG_USE_SHAREABLE 0x0002
+#define VIRTIO_GPU_BLOB_FLAG_USE_CROSS_DEVICE 0x0004
+ /* zero is invalid blob mem */
+ __le32 blob_mem;
+ __le32 blob_flags;
+ __le64 blob_id;
+ __le64 size;
+ __le32 nr_entries;
+ /*
+ * sizeof(nr_entries * virtio_gpu_mem_entry) bytes follow
+ */
+};
+
+/* VIRTIO_GPU_CMD_SET_SCANOUT_BLOB */
+struct virtio_gpu_set_scanout_blob {
+ struct virtio_gpu_ctrl_hdr hdr;
+ struct virtio_gpu_rect r;
+ __le32 scanout_id;
+ __le32 resource_id;
+ __le32 width;
+ __le32 height;
+ __le32 format;
+ __le32 padding;
+ __le32 strides[4];
+ __le32 offsets[4];
+};
+
#endif
--
2.26.2
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