Users can disable MCA polling by setting the "ignore_ce" parameter or by
setting "check_interval=0". This tells the kernel to *not* start the MCE
timer on a CPU.
If the user did not disable CMCI, then storms can occur. When these
happen, the MCE timer will be started with a fixed interval. After the
storm subsides, the timer's next interval is set to check_interval.
This disregards the user's input through "ignore_ce" and
"check_interval". Furthermore, if "check_interval=0", then the new timer
will run faster than expected.
Create a new helper to check these conditions and use it when a CMCI
storm ends.
Fixes: 7eae17c4add5 ("x86/mce: Add per-bank CMCI storm mitigation")
Signed-off-by: Yazen Ghannam <yazen.ghannam@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
Notes:
Link:
https://lore.kernel.org/r/20250415-wip-mca-updates-v3-17-8ffd9eb4aa56@xxxxxxx
v3->v4:
* Update commit message.
* Move to beginning of set.
* Note: Polling vs thresholding use case updates not yet addressed.
v2->v3:
* New in v3.
arch/x86/kernel/cpu/mce/core.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index 07d61937427f..ae2e2d8ec99b 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -1740,6 +1740,11 @@ static void mc_poll_banks_default(void)
void (*mc_poll_banks)(void) = mc_poll_banks_default;
+static bool should_enable_timer(unsigned long iv)
+{
+ return !mca_cfg.ignore_ce && iv;
+}
+
static void mce_timer_fn(struct timer_list *t)
{
struct timer_list *cpu_t = this_cpu_ptr(&mce_timer);
@@ -1763,7 +1768,7 @@ static void mce_timer_fn(struct timer_list *t)
if (mce_get_storm_mode()) {
__start_timer(t, HZ);
- } else {
+ } else if (should_enable_timer(iv)) {
__this_cpu_write(mce_next_interval, iv);
__start_timer(t, iv);
}
@@ -2156,7 +2161,7 @@ static void mce_start_timer(struct timer_list *t)
{
unsigned long iv = check_interval * HZ;
- if (mca_cfg.ignore_ce || !iv)
+ if (!should_enable_timer(iv))
return;
this_cpu_write(mce_next_interval, iv);
--
2.49.0
