x86/mce/amd: Make threshold bank setting hotplug robust

Handle the cases when the CPU goes offline before the bank
setting/reading happens.

 [ bp: Write commit message. ]

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200403161943.1458-8-bp@alien8.de

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 16e7aea..15c87b8 100644 (file)
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -386,6 +386,10 @@ 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))
+               return;
+
        rdmsr(tr->b->address, lo, hi);
 
        if (tr->b->threshold_limit < (hi & THRESHOLD_MAX))
@@ -1085,7 +1089,8 @@ store_interrupt_enable(struct threshold_block *b, const char *buf, size_t size)
        memset(&tr, 0, sizeof(tr));
        tr.b            = b;
 
-       smp_call_function_single(b->cpu, threshold_restart_bank, &tr, 1);
+       if (smp_call_function_single(b->cpu, threshold_restart_bank, &tr, 1))
+               return -ENODEV;
 
        return size;
 }
@@ -1109,7 +1114,8 @@ store_threshold_limit(struct threshold_block *b, const char *buf, size_t size)
        b->threshold_limit = new;
        tr.b = b;
 
-       smp_call_function_single(b->cpu, threshold_restart_bank, &tr, 1);
+       if (smp_call_function_single(b->cpu, threshold_restart_bank, &tr, 1))
+               return -ENODEV;
 
        return size;
 }
@@ -1118,7 +1124,9 @@ static ssize_t show_error_count(struct threshold_block *b, char *buf)
 {
        u32 lo, hi;
 
-       rdmsr_on_cpu(b->cpu, b->address, &lo, &hi);
+       /* CPU might be offline by now */
+       if (rdmsr_on_cpu(b->cpu, b->address, &lo, &hi))
+               return -ENODEV;
 
        return sprintf(buf, "%u\n", ((hi & THRESHOLD_MAX) -
                                     (THRESHOLD_MAX - b->threshold_limit)));