linux-kernel - RE: [RFC] x86_64: A real proposal for iret-less return to kernel

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Date:	Wed, 21 May 2014 22:18:33 +0000
From:	"Luck, Tony" <tony.luck@...el.com>
To:	Andy Lutomirski <luto@...capital.net>
CC:	Borislav Petkov <bp@...en8.de>, Jiri Kosina <jkosina@...e.cz>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Andi Kleen" <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>
Subject: RE: [RFC] x86_64: A real proposal for iret-less return to kernel

>> That TIF_MCE_NOTIFY prevents the return to user mode, and we end up in mce_notify_process().
>
> Why is this necessary?

The recovery path has to do more than just send a signal - it needs to walk processes and
"mm"s to see which have mapped the physical address that the h/w told us has gone bad.

-Tony