[PATCH] drm/etnaviv: Flush the tile status cache through both the PE and BLT

[Christian Gmeiner]

From: Christian Gmeiner <cgmeiner@xxxxxxxxxx>

Since commit f232d9ec029c ("drm/etnaviv: fix TS cache flushing on GPUs
with BLT engine"), jobs on GPUs with a BLT engine use a BLT command to
flush the tile status cache instead of TS_FLUSH_CACHE, which is broken
on most of these GPUs.

GC7000 r6008/r6009 and GC8200 r6401 are the other way around:
TS_FLUSH_CACHE works, but the BLT command does not flush the cache.
The vendor driver handles these GPUs using TS_FLUSH_CACHE, but the
etnaviv kernel driver has no way to identify them.

As a result, dirty tile status cache lines survive the end of a job.
They are written back by the next cache flush, using the page table of
the job issuing it. If that job belongs to another process, the write
goes to the wrong address space.

On GC7000 r6009 this causes MMU faults and GPU recoveries blamed on an
innocent process. I see around 1100 per run of a multisample
depth/stencil test running alongside two other GPU clients.

Emit both flushes at the end of every job on GPUs with a BLT engine.
Whichever does not work on a given GPU is a no-op. Since dirty lines
are only written back once, this costs one additional state load per
job.

Fixes: f232d9ec029c ("drm/etnaviv: fix TS cache flushing on GPUs with BLT engine")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Christian Gmeiner <cgmeiner@xxxxxxxxxx>
---
 drivers/gpu/drm/etnaviv/etnaviv_buffer.c | 40 ++++++++++++++------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
index 03b2576af67f..99c91a9eecf1 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_buffer.c
@@ -168,6 +168,17 @@ u16 etnaviv_buffer_config_pta(struct etnaviv_gpu *gpu, unsigned short id)
 	return buffer->user_size / 8;
 }
 
+static void etnaviv_cmd_flush_ts(struct etnaviv_cmdbuf *buffer, bool has_blt)
+{
+	CMD_LOAD_STATE(buffer, VIVS_TS_FLUSH_CACHE, VIVS_TS_FLUSH_CACHE_FLUSH);
+
+	if (has_blt) {
+		CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x1);
+		CMD_LOAD_STATE(buffer, VIVS_BLT_SET_COMMAND, 0x1);
+		CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x0);
+	}
+}
+
 void etnaviv_buffer_end(struct etnaviv_gpu *gpu)
 {
 	struct etnaviv_cmdbuf *buffer = &gpu->buffer;
@@ -191,7 +202,7 @@ void etnaviv_buffer_end(struct etnaviv_gpu *gpu)
 		unsigned int dwords = 7;
 
 		if (has_blt)
-			dwords += 10;
+			dwords += 11;
 
 		link_target = etnaviv_buffer_reserve(gpu, buffer, dwords);
 
@@ -204,16 +215,8 @@ void etnaviv_buffer_end(struct etnaviv_gpu *gpu)
 			CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x0);
 		}
 		CMD_LOAD_STATE(buffer, VIVS_GL_FLUSH_CACHE, flush);
-		if (gpu->exec_state == ETNA_PIPE_3D) {
-			if (has_blt) {
-				CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x1);
-				CMD_LOAD_STATE(buffer, VIVS_BLT_SET_COMMAND, 0x1);
-				CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x0);
-			} else {
-				CMD_LOAD_STATE(buffer, VIVS_TS_FLUSH_CACHE,
-					       VIVS_TS_FLUSH_CACHE_FLUSH);
-			}
-		}
+		if (gpu->exec_state == ETNA_PIPE_3D)
+			etnaviv_cmd_flush_ts(buffer, has_blt);
 		CMD_SEM(buffer, SYNC_RECIPIENT_FE, SYNC_RECIPIENT_PE);
 		CMD_STALL(buffer, SYNC_RECIPIENT_FE, SYNC_RECIPIENT_PE);
 		if (has_blt) {
@@ -400,12 +403,12 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 	return_dwords = 7;
 
 	/*
-	 * When the BLT engine is present we need 6 more dwords in the return
+	 * When the BLT engine is present we need 7 more dwords in the return
 	 * target: 3 enable/flush/disable + 4 enable/semaphore stall/disable,
-	 * but we don't need the normal TS flush state.
+	 * on top of the normal TS flush state.
 	 */
 	if (has_blt)
-		return_dwords += 6;
+		return_dwords += 7;
 
 	return_target = etnaviv_buffer_reserve(gpu, buffer, return_dwords);
 	CMD_LINK(cmdbuf, return_dwords, return_target);
@@ -422,14 +425,7 @@ void etnaviv_buffer_queue(struct etnaviv_gpu *gpu, u32 exec_state,
 				       VIVS_GL_FLUSH_CACHE_DEPTH |
 				       VIVS_GL_FLUSH_CACHE_COLOR |
 				       VIVS_GL_FLUSH_CACHE_SHADER_L1);
-		if (has_blt) {
-			CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x1);
-			CMD_LOAD_STATE(buffer, VIVS_BLT_SET_COMMAND, 0x1);
-			CMD_LOAD_STATE(buffer, VIVS_BLT_ENABLE, 0x0);
-		} else {
-			CMD_LOAD_STATE(buffer, VIVS_TS_FLUSH_CACHE,
-					       VIVS_TS_FLUSH_CACHE_FLUSH);
-		}
+		etnaviv_cmd_flush_ts(buffer, has_blt);
 	}
 	CMD_SEM(buffer, SYNC_RECIPIENT_FE, SYNC_RECIPIENT_PE);
 	CMD_STALL(buffer, SYNC_RECIPIENT_FE, SYNC_RECIPIENT_PE);

---
base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4
change-id: 20261102-etna-pe-ts-flush-ffa01363b98c

Best regards,
-- 
Christian Gmeiner <cgmeiner@xxxxxxxxxx>