[PATCH] drm/amdgpu: fix drm leases being broken on radv

[Andres Rodriguez]

After a recent commit, access to the DRM_AUTH ioctls become more
permissive. This resulted in a buggy check for drm_master capabilities
inside radv stop working.

This commit adds a backwards compatibility workaround so that the radv
drm_master check keeps working as previously expected.

This fixes SteamVR and other drm lease based apps being broken since
v5.1-rc1

>From the usermode side, radv will also be fixed to properly test for
master capabilities:
https://gitlab.freedesktop.org/mesa/mesa/merge_requests/669

Fixes: 8059add0478e ("drm: allow render capable master with DRM_AUTH ioctls")
Signed-off-by: Andres Rodriguez <andresx7 at gmail.com>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: David Airlie <airlied at linux.ie>
Cc: Emil Velikov <emil.velikov at collabora.com>
Cc: Alex Deucher <alexander.deucher at amd.com>
Cc: Keith Packard <keithp at keithp.com>
Reviewed-by: Keith Packard <keithp at keithp.com>
Reviewed-by: Daniel Vetter <daniel at ffwll.ch>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu.h     |  3 +++
 drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c |  2 ++
 drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 22 ++++++++++++++++++++++
 3 files changed, 27 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 8d0d7f3dd5fb..e67bfee8d411 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -409,6 +409,9 @@ struct amdgpu_fpriv {
 	struct mutex		bo_list_lock;
 	struct idr		bo_list_handles;
 	struct amdgpu_ctx_mgr	ctx_mgr;
+
+	/* Part of a backwards compatibility hack */
+	bool			is_first_ioctl;
 };
 
 int amdgpu_file_to_fpriv(struct file *filp, struct amdgpu_fpriv **fpriv);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 7419ea8a388b..cd438afa7092 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -1128,6 +1128,7 @@ long amdgpu_drm_ioctl(struct file *filp,
 		      unsigned int cmd, unsigned long arg)
 {
 	struct drm_file *file_priv = filp->private_data;
+	struct amdgpu_fpriv *fpriv = file_priv->driver_priv;
 	struct drm_device *dev;
 	long ret;
 	dev = file_priv->minor->dev;
@@ -1136,6 +1137,7 @@ long amdgpu_drm_ioctl(struct file *filp,
 		return ret;
 
 	ret = drm_ioctl(filp, cmd, arg);
+	fpriv->is_first_ioctl = false;
 
 	pm_runtime_mark_last_busy(dev->dev);
 	pm_runtime_put_autosuspend(dev->dev);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
index e860412043bb..00c0a2fb2a69 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
@@ -455,6 +455,7 @@ static int amdgpu_hw_ip_info(struct amdgpu_device *adev,
 static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
 {
 	struct amdgpu_device *adev = dev->dev_private;
+	struct amdgpu_fpriv *fpriv = filp->driver_priv;
 	struct drm_amdgpu_info *info = data;
 	struct amdgpu_mode_info *minfo = &adev->mode_info;
 	void __user *out = (void __user *)(uintptr_t)info->return_pointer;
@@ -470,6 +471,26 @@ static int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file
 
 	switch (info->query) {
 	case AMDGPU_INFO_ACCEL_WORKING:
+		/* HACK: radv has a fragile open-coded check for drm master
+		 * The pattern for the call is:
+		 *     open(DRM_NODE_PRIMARY)
+		 *     drmModeCommandWrite( query=AMDGPU_INFO_ACCEL_WORKING )
+		 *
+		 * After commit 8059add04 this check stopped working due to
+		 * operations on a primary node from non-master clients becoming
+		 * more permissive.
+		 *
+		 * This backwards compatibility hack targets the calling pattern
+		 * above to fail radv from thinking it has master access to the
+		 * display system ( without reverting 8059add04 ).
+		 *
+		 * Users of libdrm will not be affected as some other ioctls are
+		 * performed between open() and the AMDGPU_INFO_ACCEL_WORKING
+		 * query.
+		 */
+		if (fpriv->is_first_ioctl && !filp->is_master)
+			return -EACCES;
+
 		ui32 = adev->accel_working;
 		return copy_to_user(out, &ui32, min(size, 4u)) ? -EFAULT : 0;
 	case AMDGPU_INFO_CRTC_FROM_ID:
@@ -987,6 +1008,7 @@ int amdgpu_driver_open_kms(struct drm_device *dev, struct drm_file *file_priv)
 			goto error_vm;
 	}
 
+	fpriv->is_first_ioctl = true;
 	mutex_init(&fpriv->bo_list_lock);
 	idr_init(&fpriv->bo_list_handles);
 
-- 
2.19.1