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The IPI shorthand functionality delivers IPI/NMI broadcasts to all CPUs in the system. This can have similar side effects as the MCE broadcasting when CPUs are waiting in the BIOS or are offlined. The kernel tracks already the state of offlined CPUs whether they have been brought up at least once so that the CR4 MCE bit is set to make sure that MCE broadcasts can't brick the machine. Utilize that information and compare it to the cpu_present_mask. If all present CPUs have been brought up at least once then the broadcast side effect is mitigated by disabling regular interrupt/IPI delivery in the APIC itself and by the cpu offline check at the begin of the NMI handler. Use a static key to switch between broadcasting via shorthands or sending the IPI/NMI one by one. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20190722105220.386410643@linutronix.de
67 lines
2 KiB
C
67 lines
2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Historical copyright notices:
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*
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* Copyright 2004 James Cleverdon, IBM.
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* (c) 1995 Alan Cox, Building #3 <alan@redhat.com>
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* (c) 1998-99, 2000 Ingo Molnar <mingo@redhat.com>
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* (c) 2002,2003 Andi Kleen, SuSE Labs.
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*/
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#include <linux/jump_label.h>
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#include <asm/apic.h>
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/* APIC flat 64 */
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void flat_init_apic_ldr(void);
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/* X2APIC */
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int x2apic_apic_id_valid(u32 apicid);
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int x2apic_apic_id_registered(void);
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void __x2apic_send_IPI_dest(unsigned int apicid, int vector, unsigned int dest);
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unsigned int x2apic_get_apic_id(unsigned long id);
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u32 x2apic_set_apic_id(unsigned int id);
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int x2apic_phys_pkg_id(int initial_apicid, int index_msb);
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void x2apic_send_IPI_self(int vector);
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/* IPI */
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DECLARE_STATIC_KEY_FALSE(apic_use_ipi_shorthand);
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static inline unsigned int __prepare_ICR(unsigned int shortcut, int vector,
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unsigned int dest)
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{
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unsigned int icr = shortcut | dest;
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switch (vector) {
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default:
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icr |= APIC_DM_FIXED | vector;
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break;
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case NMI_VECTOR:
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icr |= APIC_DM_NMI;
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break;
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}
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return icr;
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}
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void __default_send_IPI_shortcut(unsigned int shortcut, int vector);
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/*
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* This is used to send an IPI with no shorthand notation (the destination is
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* specified in bits 56 to 63 of the ICR).
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*/
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void __default_send_IPI_dest_field(unsigned int mask, int vector, unsigned int dest);
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void default_send_IPI_single(int cpu, int vector);
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void default_send_IPI_single_phys(int cpu, int vector);
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void default_send_IPI_mask_sequence_phys(const struct cpumask *mask, int vector);
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void default_send_IPI_mask_allbutself_phys(const struct cpumask *mask, int vector);
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#ifdef CONFIG_X86_32
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void default_send_IPI_mask_sequence_logical(const struct cpumask *mask, int vector);
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void default_send_IPI_mask_allbutself_logical(const struct cpumask *mask, int vector);
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void default_send_IPI_mask_logical(const struct cpumask *mask, int vector);
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void default_send_IPI_allbutself(int vector);
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void default_send_IPI_all(int vector);
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void default_send_IPI_self(int vector);
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#endif
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