linux-kernel - [PATCH 5.14 163/432] drm/amdgpu: Fix koops when accessing RAS EEPROM

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Message-Id: <20210916155816.273246131@linuxfoundation.org>
Date:   Thu, 16 Sep 2021 17:58:32 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Alexander Deucher <Alexander.Deucher@....com>,
        John Clements <john.clements@....com>,
        Hawking Zhang <Hawking.Zhang@....com>,
        Luben Tuikov <luben.tuikov@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.14 163/432] drm/amdgpu: Fix koops when accessing RAS EEPROM

From: Luben Tuikov <luben.tuikov@....com>

[ Upstream commit 1d9d2ca85b32605ac9c74c8fa42d0c1cfbe019d4 ]

Debugfs RAS EEPROM files are available when
the ASIC supports RAS, and when the debugfs is
enabled, an also when "ras_enable" module
parameter is set to 0. However in this case,
we get a kernel oops when accessing some of
the "ras_..." controls in debugfs. The reason
for this is that struct amdgpu_ras::adev is
unset. This commit sets it, thus enabling access
to those facilities. Note that this facilitates
EEPROM access and not necessarily RAS features or
functionality.

Cc: Alexander Deucher <Alexander.Deucher@....com>
Cc: John Clements <john.clements@....com>
Cc: Hawking Zhang <Hawking.Zhang@....com>
Signed-off-by: Luben Tuikov <luben.tuikov@....com>
Acked-by: Alexander Deucher <Alexander.Deucher@....com>
Signed-off-by: Alex Deucher <alexander.deucher@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
index fc66aca28594..95d5842385b3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ras.c
@@ -1966,11 +1966,20 @@ int amdgpu_ras_recovery_init(struct amdgpu_device *adev)
 	bool exc_err_limit = false;
 	int ret;
 
-	if (adev->ras_enabled && con)
-		data = &con->eh_data;
-	else
+	if (!con)
+		return 0;
+
+	/* Allow access to RAS EEPROM via debugfs, when the ASIC
+	 * supports RAS and debugfs is enabled, but when
+	 * adev->ras_enabled is unset, i.e. when "ras_enable"
+	 * module parameter is set to 0.
+	 */
+	con->adev = adev;
+
+	if (!adev->ras_enabled)
 		return 0;
 
+	data = &con->eh_data;
 	*data = kmalloc(sizeof(**data), GFP_KERNEL | __GFP_ZERO);
 	if (!*data) {
 		ret = -ENOMEM;
@@ -1980,7 +1989,6 @@ int amdgpu_ras_recovery_init(struct amdgpu_device *adev)
 	mutex_init(&con->recovery_lock);
 	INIT_WORK(&con->recovery_work, amdgpu_ras_do_recovery);
 	atomic_set(&con->in_recovery, 0);
-	con->adev = adev;
 
 	max_eeprom_records_len = amdgpu_ras_eeprom_get_record_max_length();
 	amdgpu_ras_validate_threshold(adev, max_eeprom_records_len);
-- 
2.30.2