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Message-ID:
<IA1PR12MB6532446BE6F20C7C5F8621C9F2692@IA1PR12MB6532.namprd12.prod.outlook.com>
Date: Wed, 10 Jan 2024 12:33:40 +0000
From: "Zhang, Julia" <Julia.Zhang@....com>
To: "Zhang, Julia" <Julia.Zhang@....com>, Gurchetan Singh
<gurchetansingh@...omium.org>, Chia-I Wu <olvaffe@...il.com>, David Airlie
<airlied@...hat.com>, Gerd Hoffmann <kraxel@...hat.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
"amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
"virtualization@...ts.linux-foundation.org"
<virtualization@...ts.linux-foundation.org>, "Deucher, Alexander"
<Alexander.Deucher@....com>, "Koenig, Christian" <Christian.Koenig@....com>,
David Airlie <airlied@...il.com>, Erik Faye-Lund <kusmabite@...il.com>,
"Olsak, Marek" <Marek.Olsak@....com>, "Pelloux-Prayer, Pierre-Eric"
<Pierre-eric.Pelloux-prayer@....com>, "Huang, Honglei1"
<Honglei1.Huang@....com>, "Chen, Jiqian" <Jiqian.Chen@....com>, "Huang, Ray"
<Ray.Huang@....com>, Daniel Stone <daniels@...labora.com>
Subject: Re: [PATCH 1/1] drm/virtio: Implement RESOURCE_GET_LAYOUT ioctl
On 2024/1/10 18:47, Daniel Vetter wrote:
> On Thu, Dec 21, 2023 at 06:00:16PM +0800, Julia Zhang wrote:
>> From: Daniel Stone <daniels@...labora.com>
>>
>> Add a new ioctl to allow the guest VM to discover how the guest
>> actually allocated the underlying buffer, which allows buffers to
>> be used for GL<->Vulkan interop and through standard window systems.
>> It's also a step towards properly supporting modifiers in the guest.
>>
>> Signed-off-by: Daniel Stone <daniels@...labora.com>
>> Co-developed-by: Julia Zhang <julia.zhang@....com> # support query
>> stride before it's created
>> Signed-off-by: Julia Zhang <julia.zhang@....com>
>> ---
>> drivers/gpu/drm/virtio/virtgpu_drv.c | 1 +
>> drivers/gpu/drm/virtio/virtgpu_drv.h | 22 ++++++++-
>> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 66 ++++++++++++++++++++++++++
>> drivers/gpu/drm/virtio/virtgpu_kms.c | 8 +++-
>> drivers/gpu/drm/virtio/virtgpu_vq.c | 63 ++++++++++++++++++++++++
>> include/uapi/drm/virtgpu_drm.h | 21 ++++++++
>> include/uapi/linux/virtio_gpu.h | 30 ++++++++++++
>> 7 files changed, 208 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
>> index 4334c7608408..98061b714b98 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_drv.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
>> @@ -148,6 +148,7 @@ static unsigned int features[] = {
>> VIRTIO_GPU_F_RESOURCE_UUID,
>> VIRTIO_GPU_F_RESOURCE_BLOB,
>> VIRTIO_GPU_F_CONTEXT_INIT,
>> + VIRTIO_GPU_F_RESOURCE_QUERY_LAYOUT,
>> };
>> static struct virtio_driver virtio_gpu_driver = {
>> .feature_table = features,
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
>> index 96365a772f77..bb5edcfeda54 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_drv.h
>> +++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
>> @@ -214,6 +214,16 @@ struct virtio_gpu_drv_cap_cache {
>> atomic_t is_valid;
>> };
>>
>> +struct virtio_gpu_query_info {
>> + uint32_t num_planes;
>> + uint64_t modifier;
>> + struct {
>> + uint64_t offset;
>> + uint32_t stride;
>> + } planes[VIRTIO_GPU_MAX_RESOURCE_PLANES];
>> + atomic_t is_valid;
>> +};
>> +
>> struct virtio_gpu_device {
>> struct drm_device *ddev;
>>
>> @@ -246,6 +256,7 @@ struct virtio_gpu_device {
>> bool has_resource_blob;
>> bool has_host_visible;
>> bool has_context_init;
>> + bool has_resource_query_layout;
>> struct virtio_shm_region host_visible_region;
>> struct drm_mm host_visible_mm;
>>
>> @@ -277,7 +288,7 @@ struct virtio_gpu_fpriv {
>> };
>>
>> /* virtgpu_ioctl.c */
>> -#define DRM_VIRTIO_NUM_IOCTLS 12
>> +#define DRM_VIRTIO_NUM_IOCTLS 13
>> extern struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS];
>> void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file);
>>
>> @@ -420,6 +431,15 @@ virtio_gpu_cmd_set_scanout_blob(struct virtio_gpu_device *vgdev,
>> uint32_t width, uint32_t height,
>> uint32_t x, uint32_t y);
>>
>> +int
>> +virtio_gpu_cmd_get_resource_layout(struct virtio_gpu_device *vgdev,
>> + struct virtio_gpu_query_info *bo_info,
>> + uint32_t width,
>> + uint32_t height,
>> + uint32_t format,
>> + uint32_t bind,
>> + uint32_t hw_res_handle);
>> +
>> /* virtgpu_display.c */
>> int virtio_gpu_modeset_init(struct virtio_gpu_device *vgdev);
>> void virtio_gpu_modeset_fini(struct virtio_gpu_device *vgdev);
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
>> index b24b11f25197..216c04314177 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
>> @@ -107,6 +107,9 @@ static int virtio_gpu_getparam_ioctl(struct drm_device *dev, void *data,
>> case VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs:
>> value = vgdev->capset_id_mask;
>> break;
>> + case VIRTGPU_PARAM_RESOURCE_QUERY_LAYOUT:
>> + value = vgdev->has_resource_query_layout ? 1 : 0;
>> + break;
>> default:
>> return -EINVAL;
>> }
>> @@ -668,6 +671,65 @@ static int virtio_gpu_context_init_ioctl(struct drm_device *dev,
>> return ret;
>> }
>>
>> +static int virtio_gpu_resource_query_layout_ioctl(struct drm_device *dev,
>> + void *data,
>> + struct drm_file *file)
>> +{
>> + struct drm_virtgpu_resource_query_layout *args = data;
>> + struct virtio_gpu_device *vgdev = dev->dev_private;
>> + struct drm_gem_object *obj = NULL;
>> + struct virtio_gpu_object *bo = NULL;
>> + struct virtio_gpu_query_info bo_info = {0};
>> + int ret = 0;
>> + int i;
>> +
>> + if (!vgdev->has_resource_query_layout) {
>> + DRM_ERROR("failing: no RQL on host\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (args->handle > 0) {
>> + obj = drm_gem_object_lookup(file, args->handle);
>> + if (obj == NULL) {
>> + DRM_ERROR("invalid handle 0x%x\n", args->handle);
>> + return -ENOENT;
>> + }
>> + bo = gem_to_virtio_gpu_obj(obj);
>> + }
>> +
>> + ret = virtio_gpu_cmd_get_resource_layout(vgdev, &bo_info, args->width,
>> + args->height, args->format,
>> + args->bind, bo ? bo->hw_res_handle : 0);
>> + if (ret)
>> + goto out;
>> +
>> + ret = wait_event_timeout(vgdev->resp_wq,
>> + atomic_read(&bo_info.is_valid),
>> + 5 * HZ);
>> + if (!ret)
>> + goto out;
>> +
>> +valid:
>> + smp_rmb();
>
> Please, please no hand-rolling of coherency/synchronization primitives
> without writing an entire paper about why this is correct.
>
> I've done a full-length talk about this:
>
> https://blog.ffwll.ch/2023/07/eoss-prague-locking-engineering.html
>
> See the "Level 3: Lockless Tricks" section here:
>
> https://blog.ffwll.ch/2022/08/locking-hierarchy.html
>
> To fix this please just use a struct completion, which is practically what
> you hand-roll here.
>
> Since I looked, on the patch itself: It would be good to add a lot more
> context to this, like the userspace work and why exactly the kernel has to
> be in the business of knowing all this stuff. Because generally it really
> should not, ever: Userspace allocates buffers, userspace better knows how
> it allocated its buffers and should share that through userspace protocol
> (like wayland linux-dmabuf or x11 dri2/3). Why virtio breaks this needs a
> big explainer imo.
Yes I see your point, thank you very much.
Actually we are going to implement another way to get those information by
using existing submit_cmd ioctl of virtio gpu driver. We will create a buffer
in guest mesa to pass and get information between host and guest. So these
patches can be dropped.
Regards,
Julia
>
> Thanks, Sima
>
>> + WARN_ON(atomic_read(&bo_info.is_valid));
>> + args->num_planes = bo_info.num_planes;
>> + args->modifier = bo_info.modifier;
>> + for (i = 0; i < args->num_planes; i++) {
>> + args->planes[i].offset = bo_info.planes[i].offset;
>> + args->planes[i].stride = bo_info.planes[i].stride;
>> + }
>> + for (; i < VIRTIO_GPU_MAX_RESOURCE_PLANES; i++) {
>> + args->planes[i].offset = 0;
>> + args->planes[i].stride = 0;
>> + }
>> + ret = 0;
>> +
>> +out:
>> + if (obj)
>> + drm_gem_object_put(obj);
>> + return ret;
>> +}
>> +
>> struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS] = {
>> DRM_IOCTL_DEF_DRV(VIRTGPU_MAP, virtio_gpu_map_ioctl,
>> DRM_RENDER_ALLOW),
>> @@ -707,4 +769,8 @@ struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS] = {
>>
>> DRM_IOCTL_DEF_DRV(VIRTGPU_CONTEXT_INIT, virtio_gpu_context_init_ioctl,
>> DRM_RENDER_ALLOW),
>> +
>> + DRM_IOCTL_DEF_DRV(VIRTGPU_RESOURCE_QUERY_LAYOUT,
>> + virtio_gpu_resource_query_layout_ioctl,
>> + DRM_RENDER_ALLOW),
>> };
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
>> index 5a3b5aaed1f3..4f34f4145910 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_kms.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
>> @@ -175,6 +175,9 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
>> if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_BLOB)) {
>> vgdev->has_resource_blob = true;
>> }
>> + if (virtio_has_feature(vgdev->vdev, VIRTIO_GPU_F_RESOURCE_QUERY_LAYOUT)) {
>> + vgdev->has_resource_query_layout = true;
>> + }
>> if (virtio_get_shm_region(vgdev->vdev, &vgdev->host_visible_region,
>> VIRTIO_GPU_SHM_ID_HOST_VISIBLE)) {
>> if (!devm_request_mem_region(&vgdev->vdev->dev,
>> @@ -204,8 +207,9 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
>> vgdev->has_resource_blob ? '+' : '-',
>> vgdev->has_host_visible ? '+' : '-');
>>
>> - DRM_INFO("features: %ccontext_init\n",
>> - vgdev->has_context_init ? '+' : '-');
>> + DRM_INFO("features: %ccontext_init %cresource_query_layout\n",
>> + vgdev->has_context_init ? '+' : '-',
>> + vgdev->has_resource_query_layout ? '+' : '-');
>>
>> ret = virtio_find_vqs(vgdev->vdev, 2, vqs, callbacks, names, NULL);
>> if (ret) {
>> diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
>> index b1a00c0c25a7..26998a3ac4c2 100644
>> --- a/drivers/gpu/drm/virtio/virtgpu_vq.c
>> +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
>> @@ -1302,3 +1302,66 @@ void virtio_gpu_cmd_set_scanout_blob(struct virtio_gpu_device *vgdev,
>>
>> virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
>> }
>> +
>> +static void virtio_gpu_cmd_get_resource_layout_cb(struct virtio_gpu_device *vgdev,
>> + struct virtio_gpu_vbuffer *vbuf)
>> +{
>> + struct virtio_gpu_resp_resource_layout *resp =
>> + (struct virtio_gpu_resp_resource_layout *)vbuf->resp_buf;
>> + struct virtio_gpu_query_info *bo_info = vbuf->resp_cb_data;
>> + int i;
>> +
>> + vbuf->resp_cb_data = NULL;
>> +
>> + if (resp->hdr.type != VIRTIO_GPU_RESP_OK_RESOURCE_LAYOUT) {
>> + atomic_set(&bo_info->is_valid, 0);
>> + goto out;
>> + }
>> +
>> + bo_info->modifier = le64_to_cpu(resp->modifier);
>> + bo_info->num_planes = le32_to_cpu(resp->num_planes);
>> + for (i = 0; i < bo_info->num_planes; i++) {
>> + bo_info->planes[i].stride = le32_to_cpu(resp->planes[i].stride);
>> + bo_info->planes[i].offset = le32_to_cpu(resp->planes[i].offset);
>> + }
>> + smp_wmb();
>> + atomic_set(&bo_info->is_valid, 1);
>> +
>> +out:
>> + wake_up_all(&vgdev->resp_wq);
>> +}
>> +
>> +int virtio_gpu_cmd_get_resource_layout(struct virtio_gpu_device *vgdev,
>> + struct virtio_gpu_query_info *bo_info,
>> + uint32_t width,
>> + uint32_t height,
>> + uint32_t format,
>> + uint32_t bind,
>> + uint32_t hw_res_handle)
>> +{
>> + struct virtio_gpu_resource_query_layout *cmd_p;
>> + struct virtio_gpu_vbuffer *vbuf;
>> + void *resp_buf;
>> +
>> + resp_buf = kzalloc(sizeof(struct virtio_gpu_resp_resource_layout),
>> + GFP_KERNEL);
>> + if (!resp_buf)
>> + return -ENOMEM;
>> +
>> + cmd_p = virtio_gpu_alloc_cmd_resp
>> + (vgdev, &virtio_gpu_cmd_get_resource_layout_cb, &vbuf,
>> + sizeof(*cmd_p), sizeof(struct virtio_gpu_resp_resource_layout),
>> + resp_buf);
>> + memset(cmd_p, 0, sizeof(*cmd_p));
>> +
>> + cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_QUERY_LAYOUT);
>> + cmd_p->resource_id = cpu_to_le32(hw_res_handle);
>> + cmd_p->width = cpu_to_le32(width);
>> + cmd_p->height = cpu_to_le32(height);
>> + cmd_p->format = cpu_to_le32(format);
>> + cmd_p->bind = cpu_to_le32(bind);
>> + vbuf->resp_cb_data = bo_info;
>> +
>> + virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
>> + return 0;
>> +}
>> diff --git a/include/uapi/drm/virtgpu_drm.h b/include/uapi/drm/virtgpu_drm.h
>> index b1d0e56565bc..66f7c0fa1d4d 100644
>> --- a/include/uapi/drm/virtgpu_drm.h
>> +++ b/include/uapi/drm/virtgpu_drm.h
>> @@ -48,6 +48,7 @@ extern "C" {
>> #define DRM_VIRTGPU_GET_CAPS 0x09
>> #define DRM_VIRTGPU_RESOURCE_CREATE_BLOB 0x0a
>> #define DRM_VIRTGPU_CONTEXT_INIT 0x0b
>> +#define DRM_VIRTGPU_RESOURCE_QUERY_LAYOUT 0x0c
>>
>> #define VIRTGPU_EXECBUF_FENCE_FD_IN 0x01
>> #define VIRTGPU_EXECBUF_FENCE_FD_OUT 0x02
>> @@ -97,6 +98,7 @@ struct drm_virtgpu_execbuffer {
>> #define VIRTGPU_PARAM_CROSS_DEVICE 5 /* Cross virtio-device resource sharing */
>> #define VIRTGPU_PARAM_CONTEXT_INIT 6 /* DRM_VIRTGPU_CONTEXT_INIT */
>> #define VIRTGPU_PARAM_SUPPORTED_CAPSET_IDs 7 /* Bitmask of supported capability set ids */
>> +#define VIRTGPU_PARAM_RESOURCE_QUERY_LAYOUT 8 /* DRM_VIRTGPU_RESOURCE_QUERY_LAYOUT (also needs cap) */
>>
>> struct drm_virtgpu_getparam {
>> __u64 param;
>> @@ -211,6 +213,21 @@ struct drm_virtgpu_context_init {
>> __u64 ctx_set_params;
>> };
>>
>> +#define VIRTIO_GPU_MAX_RESOURCE_PLANES 4
>> +struct drm_virtgpu_resource_query_layout {
>> + __u32 handle;
>> + __u32 width;
>> + __u32 height;
>> + __u32 format;
>> + __u32 bind;
>> + __u32 num_planes;
>> + __u64 modifier;
>> + struct {
>> + __u64 offset;
>> + __u32 stride;
>> + } planes[VIRTIO_GPU_MAX_RESOURCE_PLANES];
>> +};
>> +
>> /*
>> * Event code that's given when VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK is in
>> * effect. The event size is sizeof(drm_event), since there is no additional
>> @@ -261,6 +278,10 @@ struct drm_virtgpu_context_init {
>> DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_CONTEXT_INIT, \
>> struct drm_virtgpu_context_init)
>>
>> +#define DRM_IOCTL_VIRTGPU_RESOURCE_QUERY_LAYOUT \
>> + DRM_IOWR(DRM_COMMAND_BASE + DRM_VIRTGPU_RESOURCE_QUERY_LAYOUT, \
>> + struct drm_virtgpu_resource_query_layout)
>> +
>> #if defined(__cplusplus)
>> }
>> #endif
>> diff --git a/include/uapi/linux/virtio_gpu.h b/include/uapi/linux/virtio_gpu.h
>> index f556fde07b76..547575232376 100644
>> --- a/include/uapi/linux/virtio_gpu.h
>> +++ b/include/uapi/linux/virtio_gpu.h
>> @@ -65,6 +65,11 @@
>> */
>> #define VIRTIO_GPU_F_CONTEXT_INIT 4
>>
>> +/*
>> + * VIRTIO_GPU_CMD_RESOURCE_QUERY_LAYOUT
>> + */
>> +#define VIRTIO_GPU_F_RESOURCE_QUERY_LAYOUT 5
>> +
>> enum virtio_gpu_ctrl_type {
>> VIRTIO_GPU_UNDEFINED = 0,
>>
>> @@ -95,6 +100,7 @@ enum virtio_gpu_ctrl_type {
>> VIRTIO_GPU_CMD_SUBMIT_3D,
>> VIRTIO_GPU_CMD_RESOURCE_MAP_BLOB,
>> VIRTIO_GPU_CMD_RESOURCE_UNMAP_BLOB,
>> + VIRTIO_GPU_CMD_RESOURCE_QUERY_LAYOUT,
>>
>> /* cursor commands */
>> VIRTIO_GPU_CMD_UPDATE_CURSOR = 0x0300,
>> @@ -108,6 +114,7 @@ enum virtio_gpu_ctrl_type {
>> VIRTIO_GPU_RESP_OK_EDID,
>> VIRTIO_GPU_RESP_OK_RESOURCE_UUID,
>> VIRTIO_GPU_RESP_OK_MAP_INFO,
>> + VIRTIO_GPU_RESP_OK_RESOURCE_LAYOUT,
>>
>> /* error responses */
>> VIRTIO_GPU_RESP_ERR_UNSPEC = 0x1200,
>> @@ -453,4 +460,27 @@ struct virtio_gpu_resource_unmap_blob {
>> __le32 padding;
>> };
>>
>> +/* VIRTIO_GPU_CMD_RESOURCE_QUERY_LAYOUT */
>> +struct virtio_gpu_resource_query_layout {
>> + struct virtio_gpu_ctrl_hdr hdr;
>> + __le32 resource_id;
>> + __le32 width;
>> + __le32 height;
>> + __le32 format;
>> + __le32 bind;
>> +};
>> +
>> +
>> +/* VIRTIO_GPU_RESP_OK_RESOURCE_LAYOUT */
>> +#define VIRTIO_GPU_RES_MAX_PLANES 4
>> +struct virtio_gpu_resp_resource_layout {
>> + struct virtio_gpu_ctrl_hdr hdr;
>> + __le64 modifier;
>> + __le32 num_planes;
>> + struct virtio_gpu_resource_plane {
>> + __le64 offset;
>> + __le32 stride;
>> + } planes[VIRTIO_GPU_RES_MAX_PLANES];
>> +};
>> +
>> #endif
>> --
>> 2.34.1
>>
>
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