drm/amdgpu: stop unmapping MQD for kernel queues v3

This looks unnecessary and actually extremely harmful since using kmap()
is not possible while inside the ring reset.

Remove all the extra mapping and unmapping of the MQDs.

v2: also fix debugfs
v3: fix coding style typo

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 8 insertions, 50 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
index d55c8b7fdb59..59acdbfe28d8 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c
@@ -608,59 +608,17 @@ static ssize_t amdgpu_debugfs_mqd_read(struct file *f, char __user *buf,
 				       size_t size, loff_t *pos)
 {
 	struct amdgpu_ring *ring = file_inode(f)->i_private;
-	volatile u32 *mqd;
-	u32 *kbuf;
-	int r, i;
-	uint32_t value, result;
+	ssize_t bytes = min_t(ssize_t, ring->mqd_size - *pos, size);
+	void *from = ((u8 *)ring->mqd_ptr) + *pos;
 
-	if (*pos & 3 || size & 3)
-		return -EINVAL;
-
-	kbuf = kmalloc(ring->mqd_size, GFP_KERNEL);
-	if (!kbuf)
-		return -ENOMEM;
-
-	r = amdgpu_bo_reserve(ring->mqd_obj, false);
-	if (unlikely(r != 0))
-		goto err_free;
-
-	r = amdgpu_bo_kmap(ring->mqd_obj, (void **)&mqd);
-	if (r)
-		goto err_unreserve;
-
-	/*
-	 * Copy to local buffer to avoid put_user(), which might fault
-	 * and acquire mmap_sem, under reservation_ww_class_mutex.
-	 */
-	for (i = 0; i < ring->mqd_size/sizeof(u32); i++)
-		kbuf[i] = mqd[i];
+	if (*pos > ring->mqd_size)
+		return 0;
 
-	amdgpu_bo_kunmap(ring->mqd_obj);
-	amdgpu_bo_unreserve(ring->mqd_obj);
+	if (copy_to_user(buf, from, bytes))
+		return -EFAULT;
 
-	result = 0;
-	while (size) {
-		if (*pos >= ring->mqd_size)
-			break;
-
-		value = kbuf[*pos/4];
-		r = put_user(value, (uint32_t *)buf);
-		if (r)
-			goto err_free;
-		buf += 4;
-		result += 4;
-		size -= 4;
-		*pos += 4;
-	}
-
-	kfree(kbuf);
-	return result;
-
-err_unreserve:
-	amdgpu_bo_unreserve(ring->mqd_obj);
-err_free:
-	kfree(kbuf);
-	return r;
+	*pos += bytes;
+	return bytes;
 }
 
 static const struct file_operations amdgpu_debugfs_mqd_fops = {