Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752727AbaACPic (ORCPT ); Fri, 3 Jan 2014 10:38:32 -0500 Received: from smtp.citrix.com ([66.165.176.89]:19679 "EHLO SMTP.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005AbaACPiU (ORCPT ); Fri, 3 Jan 2014 10:38:20 -0500 X-IronPort-AV: E=Sophos;i="4.95,598,1384300800"; d="scan'208";a="89567669" Date: Fri, 3 Jan 2014 15:37:21 +0000 From: Stefano Stabellini X-X-Sender: sstabellini@kaball.uk.xensource.com To: David Vrabel CC: Mukesh Rathor , Konrad Rzeszutek Wilk , , , , Subject: Re: [PATCH v12 03/18] xen/pvh: Early bootup changes in PV code (v2). In-Reply-To: <52C69F09.5010407@citrix.com> Message-ID: 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> <52C69F09.5010407@citrix.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2154 Lines: 57 On Fri, 3 Jan 2014, David Vrabel wrote: > 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. I agree -- 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/