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From: Ingo Molnar <mingo@kernel.org>
To: Rusty Russell <rusty@rustcorp.com.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Xen-devel <xen-devel@lists.xen.org>,
	David Vrabel <david.vrabel@citrix.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>,
	lguest@lists.ozlabs.org, stable@vger.kernel.org
Subject: Re: [PATCH] x86/cpu: Fix SMAP check in PVOPS environments
Date: Fri, 5 Jun 2015 09:13:20 +0200	[thread overview]
Message-ID: <20150605071319.GA20449@gmail.com> (raw)
In-Reply-To: <87lhfyuaiu.fsf@rustcorp.com.au>


* Rusty Russell <rusty@rustcorp.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

  reply	other threads:[~2015-06-05  7:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-06-03  9:31 [PATCH] x86/cpu: Fix SMAP check in PVOPS environments Andrew Cooper
2015-06-04  6:38 ` H. Peter Anvin
2015-06-04  6:38 ` H. Peter Anvin
2015-06-04  8:58   ` Andrew Cooper
2015-06-04  8:58   ` Andrew Cooper
2015-06-04 19:55     ` Rusty Russell
2015-06-04 19:55     ` Rusty Russell
2015-06-04 20:29       ` H. Peter Anvin
2015-06-05  2:58         ` Rusty Russell
2015-06-05  7:13           ` Ingo Molnar [this message]
2015-06-05  7:13           ` Ingo Molnar
2015-06-05  9:33           ` David Vrabel
2015-06-05  9:33           ` [Xen-devel] " David Vrabel
2015-06-05  2:58         ` Rusty Russell
2015-06-04 20:29       ` H. Peter Anvin
2015-11-17 14:59 ` Andrew Cooper
2015-11-17 14:59 ` Andrew Cooper
2015-11-19 10:12 ` [tip:x86/urgent] " tip-bot for Andrew Cooper
2015-11-19 10:12 ` tip-bot for Andrew Cooper
  -- strict thread matches above, loose matches on Subject: below --
2015-06-03  9:31 [PATCH] " Andrew Cooper

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