diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2014-03-07 15:05:20 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-03-23 21:38:15 -0700 |
| commit | a56c57c055ecc75f4375d60c783a0b578edd763c (patch) | |
| tree | 052089d136175229dbe54728c1c12d4e32db76b2 | |
| parent | 783d444c6dbca17d2b15918ef6b30add2ba586b8 (diff) | |
x86: Ignore NMIs that come in during early boot
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 <dzickus@redhat.com>
Link: http://lkml.kernel.org/r/1394221143-29713-1-git-send-email-dzickus@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/head_32.S | 7 | ||||
| -rw-r--r-- | 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 73afd11799c..e194842b093 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -566,6 +566,10 @@ 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 @@ -616,8 +620,9 @@ 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 a8368608ab4..9035aefdfc3 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) |