drm/radeon: fix PFP sync in vm_flush

Otherwise the next IB might start reading commands
with the page table still invalid.
Signed-off-by: Christian König <deathsimple@vodafone.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/ni.c

@@ -1586,4 +1586,8 @@ void cayman_vm_flush(struct radeon_device *rdev, int ridx, struct radeon_vm *vm)
 	/* bits 0-7 are the VM contexts0-7 */
 	radeon_ring_write(ring, PACKET0(VM_INVALIDATE_REQUEST, 0));
 	radeon_ring_write(ring, 1 << vm->id);
+
+	/* sync PFP to ME, otherwise we might get invalid PFP reads */
+	radeon_ring_write(ring, PACKET3(PACKET3_PFP_SYNC_ME, 0));
+	radeon_ring_write(ring, 0x0);
 }

drivers/gpu/drm/radeon/nid.h

@@ -502,6 +502,7 @@
 #define	PACKET3_MPEG_INDEX				0x3A
 #define	PACKET3_WAIT_REG_MEM				0x3C
 #define	PACKET3_MEM_WRITE				0x3D
+#define	PACKET3_PFP_SYNC_ME				0x42
 #define	PACKET3_SURFACE_SYNC				0x43
 #              define PACKET3_CB0_DEST_BASE_ENA    (1 << 6)
 #              define PACKET3_CB1_DEST_BASE_ENA    (1 << 7)

drivers/gpu/drm/radeon/si.c

@@ -2868,6 +2868,10 @@ void si_vm_flush(struct radeon_device *rdev, int ridx, struct radeon_vm *vm)
 	radeon_ring_write(ring, VM_INVALIDATE_REQUEST >> 2);
 	radeon_ring_write(ring, 0);
 	radeon_ring_write(ring, 1 << vm->id);
+
+	/* sync PFP to ME, otherwise we might get invalid PFP reads */
+	radeon_ring_write(ring, PACKET3(PACKET3_PFP_SYNC_ME, 0));
+	radeon_ring_write(ring, 0x0);
 }
 
 /*