Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com;
From:   Yazen Ghannam <yazen.ghannam@amd.com>
To:     <linux-edac@vger.kernel.org>
CC:     <linux-kernel@vger.kernel.org>, <tony.luck@intel.com>,
        <x86@kernel.org>, <Smita.KoralahalliChannabasappa@amd.com>,
        Yazen Ghannam <yazen.ghannam@amd.com>
Subject: [PATCH] x86/MCE/AMD: Allow thresholding interface updates after init
Date:   Tue, 7 Dec 2021 19:30:28 +0000
Message-ID: <20211207193028.9389-1-yazen.ghannam@amd.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Dec 2021 19:30:50.9560
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: d67eb8eb-40d9-476c-8a6a-08d9b9b8140c
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT034.eop-nam11.prod.protection.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR12MB1455
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Changes to the AMD Thresholding sysfs code prevents sysfs writes from
updating the underlying registers once CPU init is completed, i.e.
"threshold_banks" is set.

Allow the registers to be updated if the thresholding interface is
already initialized or if in the init path. Use the "set_lvt_off" value
to indicate if running in the init path, since this value is only set
during init.

Fixes: a037f3ca0ea0 ("x86/mce/amd: Make threshold bank setting hotplug robust")
Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
---
 arch/x86/kernel/cpu/mce/amd.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 2eadc7c4c902..408c9546ea0b 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -400,8 +400,12 @@ static void threshold_restart_bank(void *_tr)
 	struct thresh_restart *tr = _tr;
 	u32 hi, lo;
 
-	/* sysfs write might race against an offline operation */
-	if (this_cpu_read(threshold_banks))
+	/*
+	 * sysfs write might race against an offline operation.
+	 * Prevent register writes if threshold_banks are not set and this is
+	 * not called from the init path as indicated by "set_lvt_off".
+	 */
+	if (!(this_cpu_read(threshold_banks) || tr->set_lvt_off))
 		return;
 
 	rdmsr(tr->b->address, lo, hi);
-- 
2.25.1