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| author | Thomas Gleixner <tglx@linutronix.de> | 2023-10-02 14:00:08 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-10-24 15:05:55 +0200 |
| commit | 8f849ff63bcbc77670da03cb8f2b78b06257f455 (patch) | |
| tree | d53d92a3ca79ec251c1edaa3d046f6e15e3cfb1b /arch/x86/kernel/nmi.c | |
| parent | 9cab5fb776d4367e26950cf759211e948335288e (diff) | |
| download | lwn-8f849ff63bcbc77670da03cb8f2b78b06257f455.tar.gz lwn-8f849ff63bcbc77670da03cb8f2b78b06257f455.zip | |
x86/microcode: Handle "offline" CPUs correctly
Offline CPUs need to be parked in a safe loop when microcode update is
in progress on the primary CPU. Currently, offline CPUs are parked in
mwait_play_dead(), and for Intel CPUs, its not a safe instruction,
because the MWAIT instruction can be patched in the new microcode update
that can cause instability.
- Add a new microcode state 'UCODE_OFFLINE' to report status on per-CPU
basis.
- Force NMI on the offline CPUs.
Wake up offline CPUs while the update is in progress and then return
them back to mwait_play_dead() after microcode update is complete.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115903.660850472@linutronix.de
Diffstat (limited to 'arch/x86/kernel/nmi.c')
| -rw-r--r-- | arch/x86/kernel/nmi.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index a87d856a3808..2c6ede434a3b 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -502,8 +502,11 @@ DEFINE_IDTENTRY_RAW(exc_nmi) if (IS_ENABLED(CONFIG_NMI_CHECK_CPU)) raw_atomic_long_inc(&nsp->idt_calls); - if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id())) + if (IS_ENABLED(CONFIG_SMP) && arch_cpu_is_offline(smp_processor_id())) { + if (microcode_nmi_handler_enabled()) + microcode_offline_nmi_handler(); return; + } if (this_cpu_read(nmi_state) != NMI_NOT_RUNNING) { this_cpu_write(nmi_state, NMI_LATCHED); |