Date: Fri, 15 May 2015 08:54:17 +0200
From: Ingo Molnar <mingo@kernel.org>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Borislav Petkov <bp@alien8.de>, Gu Zheng <guz.fnst@cn.fujitsu.com>,
        Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
        x86@kernel.org
Subject: Re: [RFC PATCH] x86, espfix: use spin_lock rather than mutex
Message-ID: <20150515065417.GB29973@gmail.com>
References: <1431603465-12610-1-git-send-email-guz.fnst@cn.fujitsu.com>
 <20150514122621.GB29235@pd.tnic>
 <20150514182954.GB23479@gmail.com>
 <20150514212753.GE29125@pd.tnic>
 <55551E07.8080509@zytor.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <55551E07.8080509@zytor.com>
User-Agent: Mutt/1.5.23 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1337
Lines: 38


* H. Peter Anvin <hpa@zytor.com> wrote:

> On 05/14/2015 02:27 PM, Borislav Petkov wrote:
> > Remove stable@ from CC.
> > 
> > On Thu, May 14, 2015 at 08:29:55PM +0200, Ingo Molnar wrote:
> >> We could allocate them on the boot CPU side and hand them over to 
> >> the secondary CPU.
> > 
> > Yeah, something along those lines. I mean, they're allocated and 
> > in-use during the complete system lifetime, we might just as well 
> > allocate them all in one go. Btw, what's our allocator that early, 
> > memblock?
> > 
> > Still, what I find strange is why are we seeing this only now? Is 
> > it because it had to be a big box (cpu >= 128) or something else 
> > changed...?
> > 
> 
> Quite probable.  You don't really want to allocate them until you 
> know if a CPU at least exists, though.
> 
> I like Ingo's suggestion of allocating them before CPU bringup on 
> the initiating CPU.

The only slightly subtle detail with that is to use alloc_pages_node() 
with the secondary CPU's node, to make sure the espfix stack is 
NUMA-local to the CPU that is going to use it.

Thanks,

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/