drm/msm/gem: Add metadata

The EXT_external_objects extension is a bit awkward as it doesn't pass
explicit modifiers, leaving the importer to guess with incomplete
information.  In the case of vk (turnip) exporting and gl (freedreno)
importing, the "OPTIMAL_TILING_EXT" layout depends on VkImageCreateInfo
flags (among other things), which the importer does not know.  Which
unfortunately leaves us with the need for a metadata back-channel.

The contents of the metadata are defined by userspace.  The
EXT_external_objects extension is only required to work between
compatible versions of gl and vk drivers, as defined by device and
driver UUIDs.

v2: add missing metadata kfree
v3: Rework to move copy_from/to_user out from under gem obj lock
    to avoid angering lockdep about deadlocks against fs-reclaim

Signed-off-by: Rob Clark <robdclark@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/566157/

diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
index d751d2023f8423af87082838b7d1a484c7e6bd1b..75d60aab5780964ae6fcd98f59784756c17d46de 100644 (file)
--- a/drivers/gpu/drm/msm/msm_drv.c
+++ b/drivers/gpu/drm/msm/msm_drv.c
@@ -37,9 +37,10 @@
  * - 1.9.0 - Add MSM_SUBMIT_FENCE_SN_IN
  * - 1.10.0 - Add MSM_SUBMIT_BO_NO_IMPLICIT
  * - 1.11.0 - Add wait boost (MSM_WAIT_FENCE_BOOST, MSM_PREP_BOOST)
+ * - 1.12.0 - Add MSM_INFO_SET_METADATA and MSM_INFO_GET_METADATA
  */
 #define MSM_VERSION_MAJOR      1
-#define MSM_VERSION_MINOR      11
+#define MSM_VERSION_MINOR      12
 #define MSM_VERSION_PATCHLEVEL 0
 
 static void msm_deinit_vram(struct drm_device *ddev);
@@ -546,6 +547,85 @@ static int msm_ioctl_gem_info_set_iova(struct drm_device *dev,
        return msm_gem_set_iova(obj, ctx->aspace, iova);
 }
 
+static int msm_ioctl_gem_info_set_metadata(struct drm_gem_object *obj,
+                                          __user void *metadata,
+                                          u32 metadata_size)
+{
+       struct msm_gem_object *msm_obj = to_msm_bo(obj);
+       void *buf;
+       int ret;
+
+       /* Impose a moderate upper bound on metadata size: */
+       if (metadata_size > 128) {
+               return -EOVERFLOW;
+       }
+
+       /* Use a temporary buf to keep copy_from_user() outside of gem obj lock: */
+       buf = memdup_user(metadata, metadata_size);
+       if (IS_ERR(buf))
+               return PTR_ERR(buf);
+
+       ret = msm_gem_lock_interruptible(obj);
+       if (ret)
+               goto out;
+
+       msm_obj->metadata =
+               krealloc(msm_obj->metadata, metadata_size, GFP_KERNEL);
+       msm_obj->metadata_size = metadata_size;
+       memcpy(msm_obj->metadata, buf, metadata_size);
+
+       msm_gem_unlock(obj);
+
+out:
+       kfree(buf);
+
+       return ret;
+}
+
+static int msm_ioctl_gem_info_get_metadata(struct drm_gem_object *obj,
+                                          __user void *metadata,
+                                          u32 *metadata_size)
+{
+       struct msm_gem_object *msm_obj = to_msm_bo(obj);
+       void *buf;
+       int ret, len;
+
+       if (!metadata) {
+               /*
+                * Querying the size is inherently racey, but
+                * EXT_external_objects expects the app to confirm
+                * via device and driver UUIDs that the exporter and
+                * importer versions match.  All we can do from the
+                * kernel side is check the length under obj lock
+                * when userspace tries to retrieve the metadata
+                */
+               *metadata_size = msm_obj->metadata_size;
+               return 0;
+       }
+
+       ret = msm_gem_lock_interruptible(obj);
+       if (ret)
+               return ret;
+
+       /* Avoid copy_to_user() under gem obj lock: */
+       len = msm_obj->metadata_size;
+       buf = kmemdup(msm_obj->metadata, len, GFP_KERNEL);
+
+       msm_gem_unlock(obj);
+
+       if (*metadata_size < len) {
+               ret = -ETOOSMALL;
+       } else if (copy_to_user(metadata, buf, len)) {
+               ret = -EFAULT;
+       } else {
+               *metadata_size = len;
+       }
+
+       kfree(buf);
+
+       return 0;
+}
+
 static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
                struct drm_file *file)
 {
@@ -568,6 +648,8 @@ static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
                break;
        case MSM_INFO_SET_NAME:
        case MSM_INFO_GET_NAME:
+       case MSM_INFO_SET_METADATA:
+       case MSM_INFO_GET_METADATA:
                break;
        default:
                return -EINVAL;
@@ -630,6 +712,14 @@ static int msm_ioctl_gem_info(struct drm_device *dev, void *data,
                                ret = -EFAULT;
                }
                break;
+       case MSM_INFO_SET_METADATA:
+               ret = msm_ioctl_gem_info_set_metadata(
+                       obj, u64_to_user_ptr(args->value), args->len);
+               break;
+       case MSM_INFO_GET_METADATA:
+               ret = msm_ioctl_gem_info_get_metadata(
+                       obj, u64_to_user_ptr(args->value), &args->len);
+               break;
        }
 
        drm_gem_object_put(obj);

diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index db1e748daa753fa9293d883b83db2047a83b1024..32303cc8e646ae072581d512f375e6931c33a38e 100644 (file)
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c
@@ -1058,6 +1058,7 @@ static void msm_gem_free_object(struct drm_gem_object *obj)
 
        drm_gem_object_release(obj);
 
+       kfree(msm_obj->metadata);
        kfree(msm_obj);
 }
 

diff --git a/drivers/gpu/drm/msm/msm_gem.h b/drivers/gpu/drm/msm/msm_gem.h
index 8ddef544314083d0778607deeb978f354aaa4649..6352bd3cc5ed68c2ac8d7d6bbb56c3003898c799 100644 (file)
--- a/drivers/gpu/drm/msm/msm_gem.h
+++ b/drivers/gpu/drm/msm/msm_gem.h
@@ -108,6 +108,10 @@ struct msm_gem_object {
 
        char name[32]; /* Identifier to print for the debugfs files */
 
+       /* userspace metadata backchannel */
+       void *metadata;
+       u32 metadata_size;
+
        /**
         * pin_count: Number of times the pages are pinned
         *

diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
index 6c34272a13fd64d8bf0a3904efb4f48a57456a72..6f2a7ad04aa407ece8ed7f5bf7b6745bc3d9456b 100644 (file)
--- a/include/uapi/drm/msm_drm.h
+++ b/include/uapi/drm/msm_drm.h
@@ -139,6 +139,8 @@ struct drm_msm_gem_new {
 #define MSM_INFO_GET_NAME      0x03   /* get debug name, returned by pointer */
 #define MSM_INFO_SET_IOVA      0x04   /* set the iova, passed by value */
 #define MSM_INFO_GET_FLAGS     0x05   /* get the MSM_BO_x flags */
+#define MSM_INFO_SET_METADATA  0x06   /* set userspace metadata */
+#define MSM_INFO_GET_METADATA  0x07   /* get userspace metadata */
 
 struct drm_msm_gem_info {
        __u32 handle;         /* in */