x86/mce/amd: Fix threshold limit reset

commit 5f6e3b720694ad771911f637a51930f511427ce1 upstream.

The MCA threshold limit must be reset after servicing the interrupt.

Currently, the restart function doesn't have an explicit check for this.  It
makes some assumptions based on the current limit and what's in the registers.
These assumptions don't always hold, so the limit won't be reset in some
cases.

Make the reset condition explicit. Either an interrupt/overflow has occurred
or the bank is being initialized.

Signed-off-by: Yazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250624-wip-mca-updates-v4-4-236dd74f645f@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 1cf34fcc3a8e63f1bcf78086230aae1c68690f76..816b3d0512bad781823eb8be65412edb9a8982b3 100644 (file)
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -290,7 +290,6 @@ static void smca_configure(unsigned int bank, unsigned int cpu)
 
 struct thresh_restart {
        struct threshold_block  *b;
-       int                     reset;
        int                     set_lvt_off;
        int                     lvt_off;
        u16                     old_limit;
@@ -381,13 +380,13 @@ static void threshold_restart_bank(void *_tr)
 
        rdmsr(tr->b->address, lo, hi);
 
-       if (tr->b->threshold_limit < (hi & THRESHOLD_MAX))
-               tr->reset = 1;  /* limit cannot be lower than err count */
-
-       if (tr->reset) {                /* reset err count and overflow bit */
-               hi =
-                   (hi & ~(MASK_ERR_COUNT_HI | MASK_OVERFLOW_HI)) |
-                   (THRESHOLD_MAX - tr->b->threshold_limit);
+       /*
+        * Reset error count and overflow bit.
+        * This is done during init or after handling an interrupt.
+        */
+       if (hi & MASK_OVERFLOW_HI || tr->set_lvt_off) {
+               hi &= ~(MASK_ERR_COUNT_HI | MASK_OVERFLOW_HI);
+               hi |= THRESHOLD_MAX - tr->b->threshold_limit;
        } else if (tr->old_limit) {     /* change limit w/o reset */
                int new_count = (hi & THRESHOLD_MAX) +
                    (tr->old_limit - tr->b->threshold_limit);