drm/vmwgfx: Add export fence to file descriptor support

Added code to link a fence to a out_fence_fd file descriptor and
thread out_fence_fd down to vmw_execbuf_copy_fence_user() so it can be
copied into the IOCTL reply and be passed back up the the user.

v2:
Make sure to sync and clean up in case of failure

Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Deepak Singh Rawat <drawat@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

4 files changed, 70 insertions, 11 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
index 3f802e835216..d6ab22c7d263 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.h
@@ -40,6 +40,7 @@
 #include <drm/ttm/ttm_execbuf_util.h>
 #include <drm/ttm/ttm_module.h>
 #include "vmwgfx_fence.h"
+#include <linux/sync_file.h>
 
 #define VMWGFX_DRIVER_NAME "vmwgfx"
 #define VMWGFX_DRIVER_DATE "20170607"
@@ -826,7 +827,8 @@ extern int vmw_execbuf_process(struct drm_file *file_priv,
                                uint32_t dx_context_handle,
                                struct drm_vmw_fence_rep __user
                                *user_fence_rep,
-                               struct vmw_fence_obj **out_fence);
+                               struct vmw_fence_obj **out_fence,
+                               uint32_t flags);
 extern void __vmw_execbuf_release_pinned_bo(struct vmw_private *dev_priv,
                                             struct vmw_fence_obj *fence);
 extern void vmw_execbuf_release_pinned_bo(struct vmw_private *dev_priv);
@@ -841,7 +843,9 @@ extern void vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
                                         struct drm_vmw_fence_rep __user
                                         *user_fence_rep,
                                         struct vmw_fence_obj *fence,
-                                        uint32_t fence_handle);
+                                        uint32_t fence_handle,
+                                        int32_t out_fence_fd,
+                                        struct sync_file *sync_file);
 extern int vmw_validate_single_buffer(struct vmw_private *dev_priv,
                                       struct ttm_buffer_object *bo,
                                       bool interruptible,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
index f94f43cca58e..21c62a34e558 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c
@@ -3830,6 +3830,8 @@ int vmw_execbuf_fence_commands(struct drm_file *file_priv,
  * which the information should be copied.
  * @fence: Pointer to the fenc object.
  * @fence_handle: User-space fence handle.
+ * @out_fence_fd: exported file descriptor for the fence.  -1 if not used
+ * @sync_file:  Only used to clean up in case of an error in this function.
  *
  * This function copies fence information to user-space. If copying fails,
  * The user-space struct drm_vmw_fence_rep::error member is hopefully
@@ -3845,7 +3847,9 @@ vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
                             int ret,
                             struct drm_vmw_fence_rep __user *user_fence_rep,
                             struct vmw_fence_obj *fence,
-                            uint32_t fence_handle)
+                            uint32_t fence_handle,
+                            int32_t out_fence_fd,
+                            struct sync_file *sync_file)
 {
         struct drm_vmw_fence_rep fence_rep;
 
@@ -3855,6 +3859,7 @@ vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
         memset(&fence_rep, 0, sizeof(fence_rep));
 
         fence_rep.error = ret;
+        fence_rep.fd = out_fence_fd;
         if (ret == 0) {
                 BUG_ON(fence == NULL);
 
@@ -3877,6 +3882,14 @@ vmw_execbuf_copy_fence_user(struct vmw_private *dev_priv,
          * and unreference the handle.
          */
         if (unlikely(ret != 0) && (fence_rep.error == 0)) {
+                if (sync_file)
+                        fput(sync_file->file);
+
+                if (fence_rep.fd != -1) {
+                        put_unused_fd(fence_rep.fd);
+                        fence_rep.fd = -1;
+                }
+
                 ttm_ref_object_base_unref(vmw_fp->tfile,
                                           fence_handle, TTM_REF_USAGE);
                 DRM_ERROR("Fence copy error. Syncing.\n");
@@ -4052,7 +4065,8 @@ int vmw_execbuf_process(struct drm_file *file_priv,
                         uint64_t throttle_us,
                         uint32_t dx_context_handle,
                         struct drm_vmw_fence_rep __user *user_fence_rep,
-                        struct vmw_fence_obj **out_fence)
+                        struct vmw_fence_obj **out_fence,
+                        uint32_t flags)
 {
         struct vmw_sw_context *sw_context = &dev_priv->ctx;
         struct vmw_fence_obj *fence = NULL;
@@ -4062,20 +4076,33 @@ int vmw_execbuf_process(struct drm_file *file_priv,
         struct ww_acquire_ctx ticket;
         uint32_t handle;
         int ret;
+        int32_t out_fence_fd = -1;
+        struct sync_file *sync_file = NULL;
+
+
+        if (flags & DRM_VMW_EXECBUF_FLAG_EXPORT_FENCE_FD) {
+                out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
+                if (out_fence_fd < 0) {
+                        DRM_ERROR("Failed to get a fence file descriptor.\n");
+                        return out_fence_fd;
+                }
+        }
 
         if (throttle_us) {
                 ret = vmw_wait_lag(dev_priv, &dev_priv->fifo.marker_queue,
                                    throttle_us);
 
                 if (ret)
-                        return ret;
+                        goto out_free_fence_fd;
         }
 
         kernel_commands = vmw_execbuf_cmdbuf(dev_priv, user_commands,
                                              kernel_commands, command_size,
                                              &header);
-        if (IS_ERR(kernel_commands))
-                return PTR_ERR(kernel_commands);
+        if (IS_ERR(kernel_commands)) {
+                ret = PTR_ERR(kernel_commands);
+                goto out_free_fence_fd;
+        }
 
         ret = mutex_lock_interruptible(&dev_priv->cmdbuf_mutex);
         if (ret) {
@@ -4211,8 +4238,32 @@ int vmw_execbuf_process(struct drm_file *file_priv,
                 __vmw_execbuf_release_pinned_bo(dev_priv, fence);
 
         vmw_clear_validations(sw_context);
+
+        /*
+         * If anything fails here, give up trying to export the fence
+         * and do a sync since the user mode will not be able to sync
+         * the fence itself.  This ensures we are still functionally
+         * correct.
+         */
+        if (flags & DRM_VMW_EXECBUF_FLAG_EXPORT_FENCE_FD) {
+
+                sync_file = sync_file_create(&fence->base);
+                if (!sync_file) {
+                        DRM_ERROR("Unable to create sync file for fence\n");
+                        put_unused_fd(out_fence_fd);
+                        out_fence_fd = -1;
+
+                        (void) vmw_fence_obj_wait(fence, false, false,
+                                                  VMW_FENCE_WAIT_TIMEOUT);
+                } else {
+                        /* Link the fence with the FD created earlier */
+                        fd_install(out_fence_fd, sync_file->file);
+                }
+        }
+
         vmw_execbuf_copy_fence_user(dev_priv, vmw_fpriv(file_priv), ret,
-                                    user_fence_rep, fence, handle);
+                                    user_fence_rep, fence, handle,
+                                    out_fence_fd, sync_file);
 
         /* Don't unreference when handing fence out */
         if (unlikely(out_fence != NULL)) {
@@ -4263,6 +4314,9 @@ out_unlock:
 out_free_header:
         if (header)
                 vmw_cmdbuf_header_free(header);
+out_free_fence_fd:
+        if (out_fence_fd >= 0)
+                put_unused_fd(out_fence_fd);
 
         return ret;
 }
@@ -4479,7 +4533,8 @@ int vmw_execbuf_ioctl(struct drm_device *dev, unsigned long data,
                                   NULL, arg.command_size, arg.throttle_us,
                                   arg.context_handle,
                                   (void __user *)(unsigned long)arg.fence_rep,
-                                  NULL);
+                                  NULL,
+                                  arg.flags);
         ttm_read_unlock(&dev_priv->reservation_sem);
         if (unlikely(ret != 0))
                 goto out;
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
index 21563ca8ac1e..3bbad22b3748 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_fence.c
@@ -1150,7 +1150,7 @@ int vmw_fence_event_ioctl(struct drm_device *dev, void *data,
         }
 
         vmw_execbuf_copy_fence_user(dev_priv, vmw_fp, 0, user_fence_rep, fence,
-                                    handle);
+                                    handle, -1, NULL);
         vmw_fence_obj_unreference(&fence);
         return 0;
 out_no_create:
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
index 36dd7930bf5f..5d50e45ae274 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c
@@ -2494,7 +2494,7 @@ void vmw_kms_helper_buffer_finish(struct vmw_private *dev_priv,
         if (file_priv)
                 vmw_execbuf_copy_fence_user(dev_priv, vmw_fpriv(file_priv),
                                             ret, user_fence_rep, fence,
-                                            handle);
+                                            handle, -1, NULL);
         if (out_fence)
                 *out_fence = fence;
         else