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

Commit-ID: d7ac083f095d894a0b8ac0573516bfd035e6b25a Gitweb: https://git.kernel.org/tip/d7ac083f095d894a0b8ac0573516bfd035e6b25a Author: Avadhut Naik avadhut.naik@amd.com AuthorDate: Fri, 21 Nov 2025 19:04:04 Committer: Borislav Petkov (AMD) bp@alien8.de CommitterDate: Fri, 21 Nov 2025 20:33:12 +01:00

x86/mce: Do not clear bank's poll bit in mce_poll_banks on AMD SMCA systems

Currently, when a CMCI storm detected on a Machine Check bank, subsides, the bank's corresponding bit in the mce_poll_banks per-CPU variable is cleared unconditionally by cmci_storm_end().

On AMD SMCA systems, this essentially disables polling on that particular bank on that CPU. Consequently, any subsequent correctable errors or storms will not be logged.

Since AMD SMCA systems allow banks to be managed by both polling and interrupts, the polling banks bitmap for a CPU, i.e., mce_poll_banks, should not be modified when a storm subsides.

Fixes: 7eae17c4add5 ("x86/mce: Add per-bank CMCI storm mitigation") Signed-off-by: Avadhut Naik avadhut.naik@amd.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20251121190542.2447913-2-avadhut.naik@amd.com --- arch/x86/kernel/cpu/mce/threshold.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mce/threshold.c b/arch/x86/kernel/cpu/mce/threshold.c index eebaa63..f19dd5b 100644 --- a/arch/x86/kernel/cpu/mce/threshold.c +++ b/arch/x86/kernel/cpu/mce/threshold.c @@ -98,7 +98,8 @@ void cmci_storm_end(unsigned int bank) { struct mca_storm_desc *storm = this_cpu_ptr(&storm_desc);

- __clear_bit(bank, this_cpu_ptr(mce_poll_banks)); + if (!mce_flags.amd_threshold) + __clear_bit(bank, this_cpu_ptr(mce_poll_banks)); storm->banks[bank].history = 0; storm->banks[bank].in_storm_mode = false;