From 8f849ff63bcbc77670da03cb8f2b78b06257f455 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 2 Oct 2023 14:00:08 +0200 Subject: 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 Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20231002115903.660850472@linutronix.de --- arch/x86/include/asm/microcode.h | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/include/asm') diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h index 82924828a94b..0ee6ed0ff2bf 100644 --- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -73,6 +73,7 @@ static inline u32 intel_get_microcode_revision(void) #endif /* !CONFIG_CPU_SUP_INTEL */ bool microcode_nmi_handler(void); +void microcode_offline_nmi_handler(void); #ifdef CONFIG_MICROCODE_LATE_LOADING DECLARE_STATIC_KEY_FALSE(microcode_nmi_handler_enable); -- cgit v1.2.3