Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751785AbaACL3Q (ORCPT ); Fri, 3 Jan 2014 06:29:16 -0500 Received: from smtp02.citrix.com ([66.165.176.63]:13456 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750837AbaACL3P (ORCPT ); Fri, 3 Jan 2014 06:29:15 -0500 X-IronPort-AV: E=Sophos;i="4.95,597,1384300800"; d="scan'208";a="87314429" Message-ID: <52C69F09.5010407@citrix.com> Date: Fri, 3 Jan 2014 11:29:13 +0000 From: David Vrabel User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.16) Gecko/20121215 Iceowl/1.0b1 Icedove/3.0.11 MIME-Version: 1.0 To: Mukesh Rathor CC: Konrad Rzeszutek Wilk , , , , Subject: Re: [PATCH v12 03/18] xen/pvh: Early bootup changes in PV code (v2). References: <1388550945-25499-1-git-send-email-konrad.wilk@oracle.com> <1388550945-25499-4-git-send-email-konrad.wilk@oracle.com> <52C58691.4040502@citrix.com> <20140102183221.GD3021@pegasus.dumpdata.com> <20140102173438.40612127@mantra.us.oracle.com> In-Reply-To: <20140102173438.40612127@mantra.us.oracle.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.76] X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2014 Lines: 56 On 03/01/14 01:34, Mukesh Rathor wrote: > On Thu, 2 Jan 2014 13:32:21 -0500 > Konrad Rzeszutek Wilk wrote: > >> On Thu, Jan 02, 2014 at 03:32:33PM +0000, David Vrabel wrote: >>> On 01/01/14 04:35, Konrad Rzeszutek Wilk wrote: >>>> From: Mukesh Rathor >>>> >>>> In the bootup code for PVH we can trap cpuid via vmexit, so don't >>>> need to use emulated prefix call. We also check for vector >>>> callback early on, as it is a required feature. PVH also runs at >>>> default kernel IOPL. >>>> >>>> Finally, pure PV settings are moved to a separate function that >>>> are only called for pure PV, ie, pv with pvmmu. They are also >>>> #ifdef with CONFIG_XEN_PVMMU. >>> [...] >>>> @@ -331,12 +333,15 @@ static void xen_cpuid(unsigned int *ax, >>>> unsigned int *bx, break; >>>> } >>>> >>>> - asm(XEN_EMULATE_PREFIX "cpuid" >>>> - : "=a" (*ax), >>>> - "=b" (*bx), >>>> - "=c" (*cx), >>>> - "=d" (*dx) >>>> - : "0" (*ax), "2" (*cx)); >>>> + if (xen_pvh_domain()) >>>> + native_cpuid(ax, bx, cx, dx); >>>> + else >>>> + asm(XEN_EMULATE_PREFIX "cpuid" >>>> + : "=a" (*ax), >>>> + "=b" (*bx), >>>> + "=c" (*cx), >>>> + "=d" (*dx) >>>> + : "0" (*ax), "2" (*cx)); >>> >>> For this one off cpuid call it seems preferrable to me to use the >>> emulate prefix rather than diverge from PV. >> >> This was before the PV cpuid was deemed OK to be used on PVH. >> Will rip this out to use the same version. > > Whats wrong with using native cpuid? That is one of the benefits that > cpuid can be trapped via vmexit, and also there is talk of making PV > cpuid trap obsolete in the future. I suggest leaving it native. It should either use the PV interface or the HVM one, not a hybrid of the two. David -- 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/