Commit 00c092de authored by Yazen Ghannam's avatar Yazen Ghannam Committed by Borislav Petkov (AMD)
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x86/mce: Ensure user polling settings are honored when restarting timer 



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.

  [ bp: Massage. ]

Fixes: 7eae17c4 ("x86/mce: Add per-bank CMCI storm mitigation")
Signed-off-by: default avatarYazen Ghannam <yazen.ghannam@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250624-wip-mca-updates-v4-2-236dd74f645f@amd.com
parent 4c113a5b

arch/x86/kernel/cpu/mce/core.c

+10 −6
Original line number Diff line number Diff line
@@ -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);

	}
@@ -2156,12 +2161,11 @@ static void mce_start_timer(struct timer_list *t) 
{

	unsigned long iv = check_interval * HZ;



	if (mca_cfg.ignore_ce || !iv)

		return;



	if (should_enable_timer(iv)) {

		this_cpu_write(mce_next_interval, iv);

		__start_timer(t, iv);

	}

}



static void __mcheck_cpu_setup_timer(void)

{