linux-kernel - [PATCH] drm/amdgpu: Rearrange WREG32 operations in gfxhub_v2

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Message-ID: <64690ac5.170a0220.92bb3.2e7a@mx.google.com>
Date:   Sat, 20 May 2023 19:59:40 +0800
From:   ghostfly233 <ghostfly23333@...il.com>
To:     alexander.deucher@....com, christian.koenig@....com,
        Xinhui.Pan@....com
Cc:     amd-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        airlied@...il.com, daniel@...ll.ch, ghostfly23333@...il.com
Subject: [PATCH] drm/amdgpu: Rearrange WREG32 operations in gfxhub_v2_1.c

In gfxhub_v2_1_setup_vmid_config(), the GCVM_CONTEXT1_CNTL reg is
written before related GCVM_CONTEXT1_PAGE_TABLE_START_ADDR and
GCVM_CONTEXT1_PAGE_TABLE_END_ADDR regs are written, which may
cause undefined behavior.

This patch rearranges WREG32 operations in gfxhub_v2_1_setup_vmid_config(),
so that it can ensure the addresses are initialized before CNTL is enabled
and reduce the risk of encountering undefined behavior.

Signed-off-by: Zibin Liu <ghostfly23333@...il.com>
---
 drivers/gpu/drm/amd/amdgpu/gfxhub_v2_1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/gfxhub_v2_1.c b/drivers/gpu/drm/amd/amdgpu/gfxhub_v2_1.c
index 4aacbbec31e2..6d094e7315eb 100644
--- a/drivers/gpu/drm/amd/amdgpu/gfxhub_v2_1.c
+++ b/drivers/gpu/drm/amd/amdgpu/gfxhub_v2_1.c
@@ -321,8 +321,6 @@ static void gfxhub_v2_1_setup_vmid_config(struct amdgpu_device *adev)
 		tmp = REG_SET_FIELD(tmp, GCVM_CONTEXT1_CNTL,
 				    RETRY_PERMISSION_OR_INVALID_PAGE_FAULT,
 				    !adev->gmc.noretry);
-		WREG32_SOC15_OFFSET(GC, 0, mmGCVM_CONTEXT1_CNTL,
-				    i * hub->ctx_distance, tmp);
 		WREG32_SOC15_OFFSET(GC, 0, mmGCVM_CONTEXT1_PAGE_TABLE_START_ADDR_LO32,
 				    i * hub->ctx_addr_distance, 0);
 		WREG32_SOC15_OFFSET(GC, 0, mmGCVM_CONTEXT1_PAGE_TABLE_START_ADDR_HI32,
@@ -333,6 +331,8 @@ static void gfxhub_v2_1_setup_vmid_config(struct amdgpu_device *adev)
 		WREG32_SOC15_OFFSET(GC, 0, mmGCVM_CONTEXT1_PAGE_TABLE_END_ADDR_HI32,
 				    i * hub->ctx_addr_distance,
 				    upper_32_bits(adev->vm_manager.max_pfn - 1));
+		WREG32_SOC15_OFFSET(GC, 0, mmGCVM_CONTEXT1_CNTL,
+				    i * hub->ctx_distance, tmp);
 	}
 
 	hub->vm_cntx_cntl = tmp;
-- 
2.34.1