From d7ddcf921e7d0d8ebe82e89635bc9dc26ba9540d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Christian=20K=C3=B6nig?= <christian.koenig@amd.com>
Date: Wed, 27 Aug 2025 13:14:43 +0200
Subject: [PATCH 5189/5403] drm/amdgpu: reject gang submissions under SRIOV
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Gang submission means that the kernel driver guarantees that multiple
submissions are executed on the HW at the same time on different engines.

Background is that those submissions then depend on each other and each
can't finish stand alone.

SRIOV now uses world switch to preempt submissions on the engines to allow
sharing the HW resources between multiple VFs.

The problem is now that the SRIOV world switch can't know about such inter
dependencies and will cause a timeout if it waits for a partially running
gang submission.

To conclude SRIOV and gang submissions are fundamentally incompatible at
the moment. For now just disable them.

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>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
index 2e93d570153c..defb511acc5a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
@@ -273,7 +273,7 @@ static int amdgpu_cs_pass1(struct amdgpu_cs_parser *p,
 		}
 	}
 
-	if (!p->gang_size) {
+	if (!p->gang_size || (amdgpu_sriov_vf(p->adev) && p->gang_size > 1)) {
 		ret = -EINVAL;
 		goto free_all_kdata;
 	}
-- 
2.54.0

