From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: [PATCH v1 04/12] xen/hvmlite: Bootstrap HVMlite guest Date: Wed, 27 Jan 2016 10:17:56 -0500 Message-ID: <56A8DFA4.5000801__41312.7632033595$1453908127$gmane$org@oracle.com> References: <56A2C99A.2050701@citrix.com> <56A39300.8050802@citrix.com> <20160125221920.GG20964@wotan.suse.de> <56A6A7C6.8060906@oracle.com> <20160126203023.GI20964@wotan.suse.de> <56A7EA6A.2030502@oracle.com> <20160127000435.GK20964@wotan.suse.de> <20160127144240.GB552@char.us.oracle.com> <56A8D93C.6040304@citrix.com> <56A8DCFD.6040603@oracle.com> <56A8DDAA.1010205@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aORrG-0005Ep-Dx for xen-devel@lists.xenproject.org; Wed, 27 Jan 2016 15:18:10 +0000 In-Reply-To: <56A8DDAA.1010205@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: David Vrabel , Konrad Rzeszutek Wilk , "Luis R. Rodriguez" Cc: Juergen Gross , Jeremy Fitzhardinge , X86 ML , Andrew Cooper , Rusty Russell , "linux-kernel@vger.kernel.org" , Andy Lutomirski , "H. Peter Anvin" , xen-devel@lists.xenproject.org, Borislav Petkov , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= List-Id: xen-devel@lists.xenproject.org On 01/27/2016 10:09 AM, David Vrabel wrote: > On 27/01/16 15:06, Boris Ostrovsky wrote: >> On 01/27/2016 09:50 AM, David Vrabel wrote: >>> On 27/01/16 14:42, Konrad Rzeszutek Wilk wrote: >>>> On Tue, Jan 26, 2016 at 08:54:56PM -0800, Luis R. Rodriguez wrote: >>>>> On Jan 26, 2016 6:16 PM, "Luis R. Rodriguez" wrote: >>>>>> On Tue, Jan 26, 2016 at 4:04 PM, Luis R. Rodriguez >>>>> wrote: >>>>>>> You go: >>>>>>> >>>>>>> hvmlite_start_xen() --> >>>>>>> HVM stub >>>>>>> startup_64() | (startup_32() >>>>>> Hrm, does HVMlite work well with load_ucode_bsp(), note the patches to >>>>>> rebrand pv_enabled() to pv_legacy() or whatever, this PV type will not >>>>>> be legacy or crap / old, so we'd need a way to catch it if we should >>>>>> not use that code for this PV type. This begs the question, are you >>>>>> also sure other callers in startup_32() or startup_64() might be OK as >>>>>> well where previously guarded with pv_enabled() ? >>>>> Actually this call can't be used, and if early code used it prior to >>>>> setup_arch() it'd be a bug as its only properly set until later. >>>>> Vetting >>>>> for correctness of all code call is still required though and >>>>> perhaps we do >>>>> need something to catch now this PV type on early code such as this >>>>> one if >>>>> we don't want it. From what I've gathered before on other bsp ucode we >>>>> don't want ucode loaded for PV guest types through these mechanisms. >>>> It may help to not think of PVH/hvmlite as PV. It really is HVM with >>>> a lot >>>> of emulated devices removed. >>>> >>>> How does early microcode work on EFI? Does the EFI stub code have an >>>> early >>>> microcode loading code ? >>> Surely the interesting comparison here is how is (early) microcode >>> loading disabled in KVM guests? We should use the same mechanism for > ^^^^^^^^ >>> HVMlite guests. >> >> Why would we ever want to have a guest load microcode during boot? I can >> see how a (privileged) guest may want to load microcode from a shell >> (via microcode driver). > I think you missed a word when you read my reply. Yes, I missed it ;-) Why not continue relying on paravirt_enabled()? We are going to keep this in some form for HVMlite. -boris