x86/MCE/AMD: Allow thresholding interface updates after init

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@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220117161328.19148-1-yazen.ghannam@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 08831acc1d036bc31858ad192c93768763b7dba5..c0c57bd05f02dfc807bc3aa27e2310a9ec4412cb 100644 (file)
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -400,7 +400,7 @@ 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);