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Message-ID: <20120513095913.GB28863@aftab.osrc.amd.com>
Date: Sun, 13 May 2012 11:59:13 +0200
From: Borislav Petkov <bp@...64.org>
To: Tony Luck <tony.luck@...el.com>
Cc: linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
Borislav Petkov <bp@...64.org>,
Chen Gong <gong.chen@...ux.intel.com>,
"Huang, Ying" <ying.huang@...el.com>,
Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>
Subject: Re: [PATCH 1/2] x86/mce: Only restart instruction after machine
check recovery if it is safe
On Thu, May 10, 2012 at 11:01:20AM -0700, Tony Luck wrote:
> Section 15.3.1.2 of the software developer manual has this to say about the
> RIPV bit in the IA32_MCG_STATUS register:
>
> RIPV (restart IP valid) flag, bit 0 — Indicates (when set) that program
> execution can be restarted reliably at the instruction pointed to by the
> instruction pointer pushed on the stack when the machine-check exception
> is generated. When clear, the program cannot be reliably restarted at
> the pushed instruction pointer.
>
> We need to save the state of this bit in do_machine_check() and use it
> in mce_notify_process() to force a signal; even if memory_failure() says
> it made a complete recovery ... e.g. replaced a clean LRU page).
>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
> arch/x86/kernel/cpu/mcheck/mce.c | 9 ++++++---
> 1 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
> index 66e1c51..3b8ebdc 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce.c
> @@ -947,9 +947,10 @@ struct mce_info {
> atomic_t inuse;
> struct task_struct *t;
> __u64 paddr;
> + int restartable;
Is it me or does this look like a flag, or a bitfield? Instead of
wasting a whole integer for a single bit of information.
It will probably end up the same size though due to compiler padding
since this struct is currently 4 + 2*8 byte without the ->restartable
thing.
--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
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