linux-kernel - [PATCH AUTOSEL 5.12 45/49] drm/amd/amdgpu:save psp ring wptr to avoid attack

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Date:   Mon,  7 Jun 2021 12:12:11 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Victor Zhao <Victor.Zhao@....com>,
        Jingwen Chen <Jingwen.Chen2@....com>,
        Monk Liu <monk.liu@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>, amd-gfx@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.12 45/49] drm/amd/amdgpu:save psp ring wptr to avoid attack

From: Victor Zhao <Victor.Zhao@....com>

[ Upstream commit 2370eba9f552eaae3d8aa1f70b8e9eec5c560f9e ]

[Why]
When some tools performing psp mailbox attack, the readback value
of register can be a random value which may break psp.

[How]
Use a psp wptr cache machanism to aovid the change made by attack.

v2: unify change and add detailed reason

Signed-off-by: Victor Zhao <Victor.Zhao@....com>
Signed-off-by: Jingwen Chen <Jingwen.Chen2@....com>
Reviewed-by: Monk Liu <monk.liu@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h | 1 +
 drivers/gpu/drm/amd/amdgpu/psp_v11_0.c  | 3 ++-
 drivers/gpu/drm/amd/amdgpu/psp_v3_1.c   | 3 ++-
 3 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h
index cb50ba445f8c..0fd62a8e68c2 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_psp.h
@@ -76,6 +76,7 @@ struct psp_ring
 	uint64_t			ring_mem_mc_addr;
 	void				*ring_mem_handle;
 	uint32_t			ring_size;
+	uint32_t			ring_wptr;
 };
 
 /* More registers may will be supported */
diff --git a/drivers/gpu/drm/amd/amdgpu/psp_v11_0.c b/drivers/gpu/drm/amd/amdgpu/psp_v11_0.c
index c325d6f53a71..d39735a89a25 100644
--- a/drivers/gpu/drm/amd/amdgpu/psp_v11_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/psp_v11_0.c
@@ -720,7 +720,7 @@ static uint32_t psp_v11_0_ring_get_wptr(struct psp_context *psp)
 	struct amdgpu_device *adev = psp->adev;
 
 	if (amdgpu_sriov_vf(adev))
-		data = RREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_102);
+		data = psp->km_ring.ring_wptr;
 	else
 		data = RREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_67);
 
@@ -734,6 +734,7 @@ static void psp_v11_0_ring_set_wptr(struct psp_context *psp, uint32_t value)
 	if (amdgpu_sriov_vf(adev)) {
 		WREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_102, value);
 		WREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_101, GFX_CTRL_CMD_ID_CONSUME_CMD);
+		psp->km_ring.ring_wptr = value;
 	} else
 		WREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_67, value);
 }
diff --git a/drivers/gpu/drm/amd/amdgpu/psp_v3_1.c b/drivers/gpu/drm/amd/amdgpu/psp_v3_1.c
index f2e725f72d2f..908664a5774b 100644
--- a/drivers/gpu/drm/amd/amdgpu/psp_v3_1.c
+++ b/drivers/gpu/drm/amd/amdgpu/psp_v3_1.c
@@ -379,7 +379,7 @@ static uint32_t psp_v3_1_ring_get_wptr(struct psp_context *psp)
 	struct amdgpu_device *adev = psp->adev;
 
 	if (amdgpu_sriov_vf(adev))
-		data = RREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_102);
+		data = psp->km_ring.ring_wptr;
 	else
 		data = RREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_67);
 	return data;
@@ -394,6 +394,7 @@ static void psp_v3_1_ring_set_wptr(struct psp_context *psp, uint32_t value)
 		/* send interrupt to PSP for SRIOV ring write pointer update */
 		WREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_101,
 			GFX_CTRL_CMD_ID_CONSUME_CMD);
+		psp->km_ring.ring_wptr = value;
 	} else
 		WREG32_SOC15(MP0, 0, mmMP0_SMN_C2PMSG_67, value);
 }
-- 
2.30.2