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 d4e75be64a4c5424b5258525a4947e87cbfdd688..aa20b2c6881e9500f6a849d8e9bbe45dc2fad3cf 100644 (file)
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -310,7 +310,6 @@ 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;
@@ -405,13 +404,13 @@ 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);