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Message-ID: <20150605071319.GA20449@gmail.com>
Date: Fri, 5 Jun 2015 09:13:20 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Rusty Russell <rusty@...tcorp.com.au>
Cc: "H. Peter Anvin" <hpa@...or.com>,
Andrew Cooper <andrew.cooper3@...rix.com>,
Xen-devel <xen-devel@...ts.xen.org>,
David Vrabel <david.vrabel@...rix.com>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
linux-kernel@...r.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Boris Ostrovsky <boris.ostrovsky@...cle.com>,
lguest@...ts.ozlabs.org, stable@...r.kernel.org
Subject: Re: [PATCH] x86/cpu: Fix SMAP check in PVOPS environments
* Rusty Russell <rusty@...tcorp.com.au> wrote:
> As the comment in arch/x86/include/asm/paravirt_types.h says:
>
> * Get/set interrupt state. save_fl and restore_fl are only
> * expected to use X86_EFLAGS_IF; all other bits
> * returned from save_fl are undefined, and may be ignored by
> * restore_fl.
There should be no 'may' about this: under CONFIG_PARAVIRT_DEBUG=y the reminder of
the flags should be cleared (or all bits should be set: that will instantly crash
if restored verbatim), so that we trip up generic code that relies on non-IF
restoration?
Thanks,
Ingo
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