Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754527AbaGOPpE (ORCPT ); Tue, 15 Jul 2014 11:45:04 -0400 Received: from mail-la0-f54.google.com ([209.85.215.54]:52116 "EHLO mail-la0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751704AbaGOPpC (ORCPT ); Tue, 15 Jul 2014 11:45:02 -0400 MIME-Version: 1.0 In-Reply-To: <20140715153801.GX3403@laptop.dumpdata.com> References: <195642a5e9fd4515ad8ca4cd8bcffd4900df5790.1405437568.git.luto@amacapital.net> <20140715153801.GX3403@laptop.dumpdata.com> From: Andy Lutomirski Date: Tue, 15 Jul 2014 08:44:39 -0700 Message-ID: Subject: Re: [PATCH] x86_64,xen,espfix: Initialize espfix on secondary CPUs To: Konrad Rzeszutek Wilk Cc: "H. Peter Anvin" , Boris Ostrovsky , "linux-kernel@vger.kernel.org" , stable Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 15, 2014 at 8:38 AM, Konrad Rzeszutek Wilk wrote: > On Tue, Jul 15, 2014 at 08:26:41AM -0700, Andy Lutomirski wrote: >> Xen doesn't call start_secondary. > > Duh! >> >> Cc: stable@vger.kernel.org >> Signed-off-by: Andy Lutomirski >> --- >> >> espfix still doesn't seem to work on Xen (it goes boom in some way that >> I don't understand right now), but initializing all CPUs instead of just >> one of them seems like a good start. >> >> ISTM the right fix is probably to shove the espfix logic into >> native_iret and to tweak the paravirt logic so that native_iret always >> gets invoked. I suspect that Xen will need its own implementation of >> espfix64 in the hypervisor and that, ultimately, someone may want to >> stop initializing espfix64 at all on Xen guests. > > I think just disallowing would be preferrable. Disabling what? Sorry, my flu-addled brain needs more clarity. I'm currently working on a patch on top of this one to move all of the espfix64 invocation logic into native_iret, which will have the effect of preventing it from being used on Xen. Is that what you mean? --Andy > > Thanks for posting this patch! >> >> arch/x86/xen/smp.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c >> index 7005974..eea9bcc 100644 >> --- a/arch/x86/xen/smp.c >> +++ b/arch/x86/xen/smp.c >> @@ -23,6 +23,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -85,6 +86,13 @@ static void cpu_bringup(void) >> >> xen_setup_cpu_clockevents(); >> >> + /* >> + * Enable the espfix hack for this CPU >> + */ >> +#ifdef CONFIG_X86_ESPFIX64 >> + init_espfix_ap(); >> +#endif >> + >> notify_cpu_starting(cpu); >> >> set_cpu_online(cpu, true); >> -- >> 1.9.3 >> -- Andy Lutomirski AMA Capital Management, LLC -- 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/