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From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	Brian Gerst <brgerst@gmail.com>, Juergen Gross <jgross@suse.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>
Subject: [patch 05/10] x86/traps: Document do_spurious_interrupt_bug()
Date: Tue, 25 Feb 2020 22:36:41 +0100	[thread overview]
Message-ID: <20200225220216.624165786@linutronix.de> (raw)
In-Reply-To: <20200225213636.689276920@linutronix.de>

Add a comment which explains why this empty handler for a reserved vector
exists.

Requested-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/kernel/traps.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -862,6 +862,25 @@ do_simd_coprocessor_error(struct pt_regs
 dotraplinkage void
 do_spurious_interrupt_bug(struct pt_regs *regs, long error_code)
 {
+	/*
+	 * This addresses a Pentium Pro Erratum:
+	 *
+	 * PROBLEM: If the APIC subsystem is configured in mixed mode with
+	 * Virtual Wire mode implemented through the local APIC, an
+	 * interrupt vector of 0Fh (Intel reserved encoding) may be
+	 * generated by the local APIC (Int 15).  This vector may be
+	 * generated upon receipt of a spurious interrupt (an interrupt
+	 * which is removed before the system receives the INTA sequence)
+	 * instead of the programmed 8259 spurious interrupt vector.
+	 *
+	 * IMPLICATION: The spurious interrupt vector programmed in the
+	 * 8259 is normally handled by an operating system's spurious
+	 * interrupt handler. However, a vector of 0Fh is unknown to some
+	 * operating systems, which would crash if this erratum occurred.
+	 *
+	 * In theory this could be limited to 32bit, but the handler is not
+	 * hurting and who knows which other CPUs suffer from this.
+	 */
 }
 
 dotraplinkage void


  parent reply	other threads:[~2020-02-25 23:25 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-25 21:36 [patch 00/10] x86/entry: Consolidation - Part I Thomas Gleixner
2020-02-25 21:36 ` [patch 01/10] x86/entry/32: Add missing ASM_CLAC to general_protection entry Thomas Gleixner
2020-02-26  1:00   ` Frederic Weisbecker
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 02/10] x86/mce: Disable tracing and kprobes on do_machine_check() Thomas Gleixner
2020-02-26  1:13   ` Frederic Weisbecker
2020-02-26  5:29     ` Andy Lutomirski
2020-02-26 13:28       ` Peter Zijlstra
2020-02-26 15:10         ` Andy Lutomirski
2020-02-26 16:08           ` Peter Zijlstra
2020-02-26 17:28             ` Andy Lutomirski
2020-02-26 18:42               ` Borislav Petkov
2020-02-26 18:59                 ` Peter Zijlstra
2020-02-26 19:09                   ` Andy Lutomirski
2020-02-26 20:59                     ` Steven Rostedt
2020-02-26 11:18   ` Borislav Petkov
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Andy Lutomirski
2020-02-25 21:36 ` [patch 03/10] x86/entry/32: Force MCE through do_mce() Thomas Gleixner
2020-02-26  1:11   ` Frederic Weisbecker
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 04/10] x86/traps: Remove pointless irq enable from do_spurious_interrupt_bug() Thomas Gleixner
2020-02-26  1:19   ` Frederic Weisbecker
2020-02-25 21:36 ` Thomas Gleixner [this message]
2020-02-26 17:08   ` [patch 05/10] x86/traps: Document do_spurious_interrupt_bug() Frederic Weisbecker
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 06/10] x86/traps: Remove redundant declaration of do_double_fault() Thomas Gleixner
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 07/10] x86/irq: Remove useless return value from do_IRQ() Thomas Gleixner
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 08/10] x86/entry/32: Remove the 0/-1 distinction from exception entries Thomas Gleixner
2020-02-26  5:34   ` Andy Lutomirski
2020-02-26 18:42     ` Thomas Gleixner
2020-02-26 18:57       ` Andy Lutomirski
2020-02-26 19:15         ` Thomas Gleixner
2020-02-27 14:24           ` [patch V2 " Thomas Gleixner
2020-02-29 11:49             ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 09/10] x86/entry/entry_32: Route int3 through common_exception Thomas Gleixner
2020-02-26 17:35   ` Frederic Weisbecker
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-25 21:36 ` [patch 10/10] x86/traps: Stop using ist_enter/exit() in do_int3() Thomas Gleixner
2020-02-27 14:15   ` [tip: x86/entry] " tip-bot2 for Thomas Gleixner
2020-02-27 14:33   ` tip-bot2 for Andy Lutomirski
2020-02-26  5:26 ` [patch 00/10] x86/entry: Consolidation - Part I Andy Lutomirski
2020-02-26  5:35 ` Andy Lutomirski
2020-02-27 11:01 ` Alexandre Chartre

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