drm/vmwgfx: Kill unneeded legacy security features

At one point, the GPU command verifier and user-space handle manager
couldn't properly protect GPU clients from accessing each other's data.
Instead there was an elaborate mechanism to make sure only the active
master's primary clients could render. The other clients were either
put to sleep or even killed (if the master had exited). VRAM was
evicted on master switch. With the advent of render-node functionality,
we relaxed the VRAM eviction, but the other mechanisms stayed in place.

Now that the GPU  command verifier and ttm object manager properly
isolates primary clients from different master realms we can remove the
master switch related code and drop those legacy features.

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

1 files changed, 2 insertions, 161 deletions

diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
index cd0d49d8a8da..9bd925c420c9 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_drv.c
@@ -254,7 +254,6 @@ static int vmw_restrict_dma_mask;
 static int vmw_assume_16bpp;
 
 static int vmw_probe(struct pci_dev *, const struct pci_device_id *);
-static void vmw_master_init(struct vmw_master *);
 static int vmwgfx_pm_notifier(struct notifier_block *nb, unsigned long val,
 			      void *ptr);
 
@@ -764,10 +763,6 @@ static int vmw_driver_load(struct drm_device *dev, unsigned long chipset)
 	DRM_INFO("MMIO at 0x%08x size is %u kiB\n",
 		 dev_priv->mmio_start, dev_priv->mmio_size / 1024);
 
-	vmw_master_init(&dev_priv->fbdev_master);
-	ttm_lock_set_kill(&dev_priv->fbdev_master.lock, false, SIGTERM);
-	dev_priv->active_master = &dev_priv->fbdev_master;
-
 	dev_priv->mmio_virt = memremap(dev_priv->mmio_start,
 				       dev_priv->mmio_size, MEMREMAP_WB);
 
@@ -1009,18 +1004,7 @@ static void vmw_driver_unload(struct drm_device *dev)
 static void vmw_postclose(struct drm_device *dev,
 			 struct drm_file *file_priv)
 {
-	struct vmw_fpriv *vmw_fp;
-
-	vmw_fp = vmw_fpriv(file_priv);
-
-	if (vmw_fp->locked_master) {
-		struct vmw_master *vmaster =
-			vmw_master(vmw_fp->locked_master);
-
-		ttm_lock_set_kill(&vmaster->lock, true, SIGTERM);
-		ttm_vt_unlock(&vmaster->lock);
-		drm_master_put(&vmw_fp->locked_master);
-	}
+	struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
 
 	ttm_object_file_release(&vmw_fp->tfile);
 	kfree(vmw_fp);
@@ -1049,55 +1033,6 @@ out_no_tfile:
 	return ret;
 }
 
-static struct vmw_master *vmw_master_check(struct drm_device *dev,
-					   struct drm_file *file_priv,
-					   unsigned int flags)
-{
-	int ret;
-	struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
-	struct vmw_master *vmaster;
-
-	if (!drm_is_primary_client(file_priv) || !(flags & DRM_AUTH))
-		return NULL;
-
-	ret = mutex_lock_interruptible(&dev->master_mutex);
-	if (unlikely(ret != 0))
-		return ERR_PTR(-ERESTARTSYS);
-
-	if (drm_is_current_master(file_priv)) {
-		mutex_unlock(&dev->master_mutex);
-		return NULL;
-	}
-
-	/*
-	 * Check if we were previously master, but now dropped. In that
-	 * case, allow at least render node functionality.
-	 */
-	if (vmw_fp->locked_master) {
-		mutex_unlock(&dev->master_mutex);
-
-		if (flags & DRM_RENDER_ALLOW)
-			return NULL;
-
-		DRM_ERROR("Dropped master trying to access ioctl that "
-			  "requires authentication.\n");
-		return ERR_PTR(-EACCES);
-	}
-	mutex_unlock(&dev->master_mutex);
-
-	/*
-	 * Take the TTM lock. Possibly sleep waiting for the authenticating
-	 * master to become master again, or for a SIGTERM if the
-	 * authenticating master exits.
-	 */
-	vmaster = vmw_master(file_priv->master);
-	ret = ttm_read_lock(&vmaster->lock, true);
-	if (unlikely(ret != 0))
-		vmaster = ERR_PTR(ret);
-
-	return vmaster;
-}
-
 static long vmw_generic_ioctl(struct file *filp, unsigned int cmd,
 			      unsigned long arg,
 			      long (*ioctl_func)(struct file *, unsigned int,
@@ -1106,9 +1041,7 @@ static long vmw_generic_ioctl(struct file *filp, unsigned int cmd,
 	struct drm_file *file_priv = filp->private_data;
 	struct drm_device *dev = file_priv->minor->dev;
 	unsigned int nr = DRM_IOCTL_NR(cmd);
-	struct vmw_master *vmaster;
 	unsigned int flags;
-	long ret;
 
 	/*
 	 * Do extra checking on driver private ioctls.
@@ -1134,21 +1067,7 @@ static long vmw_generic_ioctl(struct file *filp, unsigned int cmd,
 	} else if (!drm_ioctl_flags(nr, &flags))
 		return -EINVAL;
 
-	vmaster = vmw_master_check(dev, file_priv, flags);
-	if (IS_ERR(vmaster)) {
-		ret = PTR_ERR(vmaster);
-
-		if (ret != -ERESTARTSYS)
-			DRM_INFO("IOCTL ERROR Command %d, Error %ld.\n",
-				 nr, ret);
-		return ret;
-	}
-
-	ret = ioctl_func(filp, cmd, arg);
-	if (vmaster)
-		ttm_read_unlock(&vmaster->lock);
-
-	return ret;
+	return ioctl_func(filp, cmd, arg);
 
 out_io_encoding:
 	DRM_ERROR("Invalid command format, ioctl %d\n",
@@ -1171,65 +1090,10 @@ static long vmw_compat_ioctl(struct file *filp, unsigned int cmd,
 }
 #endif
 
-static void vmw_master_init(struct vmw_master *vmaster)
-{
-	ttm_lock_init(&vmaster->lock);
-}
-
-static int vmw_master_create(struct drm_device *dev,
-			     struct drm_master *master)
-{
-	struct vmw_master *vmaster;
-
-	vmaster = kzalloc(sizeof(*vmaster), GFP_KERNEL);
-	if (unlikely(!vmaster))
-		return -ENOMEM;
-
-	vmw_master_init(vmaster);
-	ttm_lock_set_kill(&vmaster->lock, true, SIGTERM);
-	master->driver_priv = vmaster;
-
-	return 0;
-}
-
-static void vmw_master_destroy(struct drm_device *dev,
-			       struct drm_master *master)
-{
-	struct vmw_master *vmaster = vmw_master(master);
-
-	master->driver_priv = NULL;
-	kfree(vmaster);
-}
-
 static int vmw_master_set(struct drm_device *dev,
 			  struct drm_file *file_priv,
 			  bool from_open)
 {
-	struct vmw_private *dev_priv = vmw_priv(dev);
-	struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
-	struct vmw_master *active = dev_priv->active_master;
-	struct vmw_master *vmaster = vmw_master(file_priv->master);
-	int ret = 0;
-
-	if (active) {
-		BUG_ON(active != &dev_priv->fbdev_master);
-		ret = ttm_vt_lock(&active->lock, false, vmw_fp->tfile);
-		if (unlikely(ret != 0))
-			return ret;
-
-		ttm_lock_set_kill(&active->lock, true, SIGTERM);
-		dev_priv->active_master = NULL;
-	}
-
-	ttm_lock_set_kill(&vmaster->lock, false, SIGTERM);
-	if (!from_open) {
-		ttm_vt_unlock(&vmaster->lock);
-		BUG_ON(vmw_fp->locked_master != file_priv->master);
-		drm_master_put(&vmw_fp->locked_master);
-	}
-
-	dev_priv->active_master = vmaster;
-
 	/*
 	 * Inform a new master that the layout may have changed while
 	 * it was gone.
@@ -1244,31 +1108,10 @@ static void vmw_master_drop(struct drm_device *dev,
 			    struct drm_file *file_priv)
 {
 	struct vmw_private *dev_priv = vmw_priv(dev);
-	struct vmw_fpriv *vmw_fp = vmw_fpriv(file_priv);
-	struct vmw_master *vmaster = vmw_master(file_priv->master);
-	int ret;
-
-	/**
-	 * Make sure the master doesn't disappear while we have
-	 * it locked.
-	 */
 
-	vmw_fp->locked_master = drm_master_get(file_priv->master);
-	ret = ttm_vt_lock(&vmaster->lock, false, vmw_fp->tfile);
 	vmw_kms_legacy_hotspot_clear(dev_priv);
-	if (unlikely((ret != 0))) {
-		DRM_ERROR("Unable to lock TTM at VT switch.\n");
-		drm_master_put(&vmw_fp->locked_master);
-	}
-
-	ttm_lock_set_kill(&vmaster->lock, false, SIGTERM);
-
 	if (!dev_priv->enable_fb)
 		vmw_svga_disable(dev_priv);
-
-	dev_priv->active_master = &dev_priv->fbdev_master;
-	ttm_lock_set_kill(&dev_priv->fbdev_master.lock, false, SIGTERM);
-	ttm_vt_unlock(&dev_priv->fbdev_master.lock);
 }
 
 /**
@@ -1546,8 +1389,6 @@ static struct drm_driver driver = {
 	.disable_vblank = vmw_disable_vblank,
 	.ioctls = vmw_ioctls,
 	.num_ioctls = ARRAY_SIZE(vmw_ioctls),
-	.master_create = vmw_master_create,
-	.master_destroy = vmw_master_destroy,
 	.master_set = vmw_master_set,
 	.master_drop = vmw_master_drop,
 	.open = vmw_driver_open,