linux-kernel - [PATCH 5.16 091/200] x86/MCE/AMD: Allow thresholding interface updates after init

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Message-Id: <20220131105236.675046425@linuxfoundation.org>
Date:   Mon, 31 Jan 2022 11:55:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Yazen Ghannam <yazen.ghannam@....com>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH 5.16 091/200] x86/MCE/AMD: Allow thresholding interface updates after init

From: Yazen Ghannam <yazen.ghannam@....com>

commit 1f52b0aba6fd37653416375cb8a1ca673acf8d5f upstream.

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@....com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/20220117161328.19148-1-yazen.ghannam@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/cpu/mce/amd.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -401,7 +401,7 @@ static void threshold_restart_bank(void
 	u32 hi, lo;
 
 	/* sysfs write might race against an offline operation */
-	if (this_cpu_read(threshold_banks))
+	if (!this_cpu_read(threshold_banks) && !tr->set_lvt_off)
 		return;
 
 	rdmsr(tr->b->address, lo, hi);