Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752273AbaDALR2 (ORCPT ); Tue, 1 Apr 2014 07:17:28 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:42393 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752240AbaDALRY (ORCPT ); Tue, 1 Apr 2014 07:17:24 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: "H. Peter Anvin" , Luis Henriques Subject: [PATCH 3.11 064/144] x86: Ignore NMIs that come in during early boot Date: Tue, 1 Apr 2014 12:14:28 +0100 Message-Id: <1396350948-29910-65-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1396350948-29910-1-git-send-email-luis.henriques@canonical.com> References: <1396350948-29910-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.11.10.7 -stable review patch. If anyone has any objections, please let me know. ------------------ From: "H. Peter Anvin" commit 5fa10196bdb5f190f595ebd048490ee52dddea0f upstream. Don Zickus reports: A customer generated an external NMI using their iLO to test kdump worked. Unfortunately, the machine hung. Disabling the nmi_watchdog made things work. I speculated the external NMI fired, caused the machine to panic (as expected) and the perf NMI from the watchdog came in and was latched. My guess was this somehow caused the hang. ---- It appears that the latched NMI stays latched until the early page table generation on 64 bits, which causes exceptions to happen which end in IRET, which re-enable NMI. Therefore, ignore NMIs that come in during early execution, until we have proper exception handling. Reported-and-tested-by: Don Zickus Link: http://lkml.kernel.org/r/1394221143-29713-1-git-send-email-dzickus@redhat.com Signed-off-by: H. Peter Anvin Signed-off-by: Luis Henriques --- arch/x86/kernel/head_32.S | 7 ++++++- arch/x86/kernel/head_64.S | 6 +++++- 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 5dd87a8..4268023 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -544,6 +544,10 @@ ENDPROC(early_idt_handlers) /* This is global to keep gas from relaxing the jumps */ ENTRY(early_idt_handler) cld + + cmpl $X86_TRAP_NMI,(%esp) + je is_nmi # Ignore NMI + cmpl $2,%ss:early_recursion_flag je hlt_loop incl %ss:early_recursion_flag @@ -594,8 +598,9 @@ ex_entry: pop %edx pop %ecx pop %eax - addl $8,%esp /* drop vector number and error code */ decl %ss:early_recursion_flag +is_nmi: + addl $8,%esp /* drop vector number and error code */ iret ENDPROC(early_idt_handler) diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index e1aabdb..33f36c7 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -343,6 +343,9 @@ early_idt_handlers: ENTRY(early_idt_handler) cld + cmpl $X86_TRAP_NMI,(%rsp) + je is_nmi # Ignore NMI + cmpl $2,early_recursion_flag(%rip) jz 1f incl early_recursion_flag(%rip) @@ -405,8 +408,9 @@ ENTRY(early_idt_handler) popq %rdx popq %rcx popq %rax - addq $16,%rsp # drop vector number and error code decl early_recursion_flag(%rip) +is_nmi: + addq $16,%rsp # drop vector number and error code INTERRUPT_RETURN ENDPROC(early_idt_handler) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/