[PATCH v2] drm/amdgpu: Remove writing GRBM_GFX_CNTL in RLCG interface under SRIOV

[Zhang, Hawking]

[AMD Official Use Only - General]

Reviewed-by: Hawking Zhang <Hawking.Zhang at amd.com>

Regards,
Hawking
From: Yifan Zha <Yifan.Zha at amd.com>
Date: Wednesday, February 1, 2023 at 13:15
To: amd-gfx at lists.freedesktop.org <amd-gfx at lists.freedesktop.org>, Deucher, Alexander <Alexander.Deucher at amd.com>, Zhang, Hawking <Hawking.Zhang at amd.com>
Cc: Chen, Horace <Horace.Chen at amd.com>, Chang, HaiJun <HaiJun.Chang at amd.com>, Zha, YiFan(Even) <Yifan.Zha at amd.com>
Subject: [PATCH v2] drm/amdgpu: Remove writing GRBM_GFX_CNTL in RLCG interface under SRIOV
[Why]
Accessing GRBM_GFX_CNTL in full access time has risk when VF is doing MMIO attacking.
Therefore, VF writing GRBM_GFX_CNTL are blocked by L1 Policy.
For RLCG interface, RLCG use SCRATCH_REG2 which is copied from GRBM_GFX_CNTL.

[How]
Remove writing GRBM_GFX_CNTL in amdgpu_virt_rlcg_reg_rw.

v2:
Remove directly writing GRBM_GFX_INDEX in amdgpu_virt_rlcg_reg_rw
as RLCG interface no need to use it.

Signed-off-by: Yifan Zha <Yifan.Zha at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
index f39391e03d46..ca5a1d026f5a 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -983,11 +983,9 @@ static u32 amdgpu_virt_rlcg_reg_rw(struct amdgpu_device *adev, u32 offset, u32 v
         if (offset == reg_access_ctrl->grbm_cntl) {
                 /* if the target reg offset is grbm_cntl, write to scratch_reg2 */
                 writel(v, scratch_reg2);
-               writel(v, ((void __iomem *)adev->rmmio) + (offset * 4));
         } else if (offset == reg_access_ctrl->grbm_idx) {
                 /* if the target reg offset is grbm_idx, write to scratch_reg3 */
                 writel(v, scratch_reg3);
-               writel(v, ((void __iomem *)adev->rmmio) + (offset * 4));
         } else {
                 /*
                  * SCRATCH_REG0   = read/write value
--
2.25.1
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