The following commit has been merged into the ras/urgent branch of tip:

Commit-ID: 00c092de6f28ebd32208aef83b02d61af2229b60 Gitweb: https://git.kernel.org/tip/00c092de6f28ebd32208aef83b02d61af2229b60 Author: Yazen Ghannam yazen.ghannam@amd.com AuthorDate: Tue, 24 Jun 2025 14:15:57 Committer: Borislav Petkov (AMD) bp@alien8.de CommitterDate: Fri, 27 Jun 2025 12:41:44 +02:00

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: 7eae17c4add5 ("x86/mce: Add per-bank CMCI storm mitigation") 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-v4-2-236dd74f645f@amd.com --- arch/x86/kernel/cpu/mce/core.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 07d6193..4da4eab 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); } @@ -2156,11 +2161,10 @@ static void mce_start_timer(struct timer_list *t) { unsigned long iv = check_interval * HZ;

- if (mca_cfg.ignore_ce || !iv) - return; - - this_cpu_write(mce_next_interval, iv); - __start_timer(t, iv); + if (should_enable_timer(iv)) { + this_cpu_write(mce_next_interval, iv); + __start_timer(t, iv); + } }

static void __mcheck_cpu_setup_timer(void)