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Message-ID: <1487888144.115017.3.camel@ranerica-desktop>
Subject: Re: [PATCH v4 15/17] x86/traps: Fixup general protection faults
 caused by UMIP
From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>, Thomas Gleixner <tglx@linutronix.de>,
        "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Brian Gerst <brgerst@gmail.com>, Chris Metcalf <cmetcalf@mellanox.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>, Liang Z Li <liang.z.li@intel.com>,
        Masami Hiramatsu <mhiramat@kernel.org>, Huang Rui <ray.huang@amd.com>,
        Jiri Slaby <jslaby@suse.cz>, Jonathan Corbet <corbet@lwn.net>,
        "Michael S. Tsirkin" <mst@redhat.com>,
        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Vlastimil Babka <vbabka@suse.cz>, Chen Yucong <slaoub@gmail.com>,
        Alexandre Julliard <julliard@winehq.org>, Stas Sergeev <stsp@list.ru>,
        Fenghua Yu <fenghua.yu@intel.com>,
        "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
        Shuah Khan <shuah@kernel.org>, linux-kernel@vger.kernel.org,
        x86@kernel.org, linux-msdos@vger.kernel.org, wine-devel@winehq.org,
        Tony Luck <tony.luck@intel.com>
Date: Thu, 23 Feb 2017 14:15:44 -0800
In-Reply-To: <20170223092724.GZ6515@twins.programming.kicks-ass.net>
References: <20170223063706.71554-1-ricardo.neri-calderon@linux.intel.com>
         <20170223063706.71554-16-ricardo.neri-calderon@linux.intel.com>
         <20170223092724.GZ6515@twins.programming.kicks-ass.net>
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On Thu, 2017-02-23 at 10:27 +0100, Peter Zijlstra wrote:
> On Wed, Feb 22, 2017 at 10:37:04PM -0800, Ricardo Neri wrote:
> > @@ -492,6 +493,9 @@ do_general_protection(struct pt_regs *regs, long error_code)
> >  	RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU");
> >  	cond_local_irq_enable(regs);
> >  
> > +	if (user_mode(regs) && (fixup_umip_exception(regs) == true))
> > +		return;
> 
> I'm thinking
> 
> 	if (user_mode(regs) && fixup_umip_exception(regs))
> 		return;
> 
> is actually easier to read.

In a previous version Andy Lutomirsky suggested that 
	if (user_mode(regs) && (fixup_umip_exception(regs) == 0))

was easier to read :). Although at the time fixup_umip_exception
returned a numeric value. Now it only returns true/false for
successful/failed emulation. If with true/false not comparing to true
makes it easier to read, I will make the change.

Thanks and BR,
Ricardo