From 6d03a247468059b0e59c821ef39e6762d4d6fc30 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 19 Jun 2024 23:00:51 +0200 Subject: Merging upstream version 6.9.2. Signed-off-by: Daniel Baumann --- arch/x86/kernel/nmi.c | 74 +++++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 60 insertions(+), 14 deletions(-) (limited to 'arch/x86/kernel/nmi.c') diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index 6da2cfa23c..ed163c8c86 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -35,6 +35,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -303,13 +304,13 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs) __this_cpu_add(nmi_stats.unknown, 1); - pr_emerg("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n", - reason, smp_processor_id()); + pr_emerg_ratelimited("Uhhuh. NMI received for unknown reason %02x on CPU %d.\n", + reason, smp_processor_id()); if (unknown_nmi_panic || panic_on_unrecovered_nmi) nmi_panic(regs, "NMI: Not continuing"); - pr_emerg("Dazed and confused, but trying to continue\n"); + pr_emerg_ratelimited("Dazed and confused, but trying to continue\n"); } NOKPROBE_SYMBOL(unknown_nmi_error); @@ -502,7 +503,7 @@ 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 (arch_cpu_is_offline(smp_processor_id())) { if (microcode_nmi_handler_enabled()) microcode_offline_nmi_handler(); return; @@ -579,7 +580,7 @@ EXPORT_SYMBOL_GPL(asm_exc_nmi_kvm_vmx); static char *nmi_check_stall_msg[] = { /* */ -/* +--------- nsp->idt_seq_snap & 0x1: CPU is in NMI handler. */ +/* +--------- nmi_seq & 0x1: CPU is currently in NMI handler. */ /* | +------ cpu_is_offline(cpu) */ /* | | +--- nsp->idt_calls_snap != atomic_long_read(&nsp->idt_calls): */ /* | | | NMI handler has been invoked. */ @@ -627,27 +628,72 @@ void nmi_backtrace_stall_check(const struct cpumask *btp) nmi_seq = READ_ONCE(nsp->idt_nmi_seq); if (nsp->idt_nmi_seq_snap + 1 == nmi_seq && (nmi_seq & 0x1)) { msgp = "CPU entered NMI handler function, but has not exited"; - } else if ((nsp->idt_nmi_seq_snap & 0x1) != (nmi_seq & 0x1)) { - msgp = "CPU is handling NMIs"; - } else { - idx = ((nsp->idt_seq_snap & 0x1) << 2) | + } else if (nsp->idt_nmi_seq_snap == nmi_seq || + nsp->idt_nmi_seq_snap + 1 == nmi_seq) { + idx = ((nmi_seq & 0x1) << 2) | (cpu_is_offline(cpu) << 1) | (nsp->idt_calls_snap != atomic_long_read(&nsp->idt_calls)); msgp = nmi_check_stall_msg[idx]; if (nsp->idt_ignored_snap != READ_ONCE(nsp->idt_ignored) && (idx & 0x1)) modp = ", but OK because ignore_nmis was set"; - if (nmi_seq & 0x1) - msghp = " (CPU currently in NMI handler function)"; - else if (nsp->idt_nmi_seq_snap + 1 == nmi_seq) + if (nsp->idt_nmi_seq_snap + 1 == nmi_seq) msghp = " (CPU exited one NMI handler function)"; + else if (nmi_seq & 0x1) + msghp = " (CPU currently in NMI handler function)"; + else + msghp = " (CPU was never in an NMI handler function)"; + } else { + msgp = "CPU is handling NMIs"; } - pr_alert("%s: CPU %d: %s%s%s, last activity: %lu jiffies ago.\n", - __func__, cpu, msgp, modp, msghp, j - READ_ONCE(nsp->recv_jiffies)); + pr_alert("%s: CPU %d: %s%s%s\n", __func__, cpu, msgp, modp, msghp); + pr_alert("%s: last activity: %lu jiffies ago.\n", + __func__, j - READ_ONCE(nsp->recv_jiffies)); } } #endif +#ifdef CONFIG_X86_FRED +/* + * With FRED, CR2/DR6 is pushed to #PF/#DB stack frame during FRED + * event delivery, i.e., there is no problem of transient states. + * And NMI unblocking only happens when the stack frame indicates + * that so should happen. + * + * Thus, the NMI entry stub for FRED is really straightforward and + * as simple as most exception handlers. As such, #DB is allowed + * during NMI handling. + */ +DEFINE_FREDENTRY_NMI(exc_nmi) +{ + irqentry_state_t irq_state; + + if (arch_cpu_is_offline(smp_processor_id())) { + if (microcode_nmi_handler_enabled()) + microcode_offline_nmi_handler(); + return; + } + + /* + * Save CR2 for eventual restore to cover the case where the NMI + * hits the VMENTER/VMEXIT region where guest CR2 is life. This + * prevents guest state corruption in case that the NMI handler + * takes a page fault. + */ + this_cpu_write(nmi_cr2, read_cr2()); + + irq_state = irqentry_nmi_enter(regs); + + inc_irq_stat(__nmi_count); + default_do_nmi(regs); + + irqentry_nmi_exit(regs, irq_state); + + if (unlikely(this_cpu_read(nmi_cr2) != read_cr2())) + write_cr2(this_cpu_read(nmi_cr2)); +} +#endif + void stop_nmi(void) { ignore_nmis++; -- cgit v1.2.3