[PATCH v2] x86/MCE/AMD: Allow thresholding interface updates after init

[Yazen Ghannam]

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@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
---
Link:
https://lkml.kernel.org/r/20211207193028.9389-1-yazen.ghannam@xxxxxxx

v1->v2:
* Add Cc: stable
* Switch logic for check and drop extra comment.

 arch/x86/kernel/cpu/mce/amd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index a1e2f41796dc..9f4b508886dd 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -423,7 +423,7 @@ static void threshold_restart_bank(void *_tr)
 	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);
-- 
2.25.1