From: David Vrabel <david.vrabel@citrix.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Xen-devel <xen-devel@lists.xen.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
<x86@kernel.org>, <linux-kernel@vger.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
"Rusty Russell" <rusty@rustcorp.com.au>,
<lguest@lists.ozlabs.org>
Subject: Re: [PATCH] [RFC] x86/cpu: Fix SMAP check in PVOPS environments
Date: Mon, 20 Apr 2015 18:11:51 +0100 [thread overview]
Message-ID: <55353357.5090902@citrix.com> (raw)
In-Reply-To: <1429549782-12962-1-git-send-email-andrew.cooper3@citrix.com>
On 20/04/15 18:09, Andrew Cooper wrote:
> There appears to be no formal statement of what pv_irq_ops.save_fl() is
> supposed to return precisely. Native returns the full flags, while lguest and
> Xen only return the Interrupt Flag, and both have comments by the
> implementations stating that only the Interrupt Flag is looked at. This may
> have been true when initially implemented, but no longer is.
>
> To make matters worse, the Xen PVOP leaves the upper bits undefined, making
> the BUG_ON() undefined behaviour. Experimentally, this now trips for 32bit PV
> guests on Broadwell hardware. The BUG_ON() is consistent for an individual
> build, but not consistent for all builds. It has also been a sitting timebomb
> since SMAP support was introduced.
>
> Use native_save_fl() instead, which will obtain an accurate view of the AC
> flag.
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
David
next prev parent reply other threads:[~2015-04-20 17:12 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-20 17:09 [PATCH] [RFC] x86/cpu: Fix SMAP check in PVOPS environments Andrew Cooper
2015-04-20 17:11 ` David Vrabel [this message]
2015-04-20 17:11 ` David Vrabel
2015-04-21 0:35 ` Andy Lutomirski
2015-04-21 0:35 ` Andy Lutomirski
2015-04-21 5:07 ` Rusty Russell
2015-04-21 5:07 ` Rusty Russell
2015-04-21 8:26 ` Andrew Cooper
2015-04-21 8:26 ` Andrew Cooper
2015-04-21 12:45 ` [RFC PATCH] x86/asm/irq: Don't use POPF but STI Ingo Molnar
2015-04-21 13:09 ` Borislav Petkov
2015-04-21 15:22 ` Ingo Molnar
2015-04-21 15:22 ` Ingo Molnar
2015-04-21 13:09 ` Borislav Petkov
2015-04-21 16:12 ` Linus Torvalds
2015-04-21 22:39 ` Andy Lutomirski
2015-04-21 22:39 ` Andy Lutomirski
2015-04-21 16:12 ` Linus Torvalds
2015-04-21 12:45 ` Ingo Molnar
2015-04-21 8:36 ` [PATCH] [RFC] x86/cpu: Fix SMAP check in PVOPS environments Jan Beulich
2015-04-21 8:36 ` [Xen-devel] " Jan Beulich
-- strict thread matches above, loose matches on Subject: below --
2015-04-20 17:09 Andrew Cooper
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