From mboxrd@z Thu Jan 1 00:00:00 1970 From: Borislav Petkov Subject: Re: [PATCH v1 1/2] x86/cpufeature: Add facility to match microcode revisions Date: Sat, 6 Oct 2018 20:39:28 +0200 Message-ID: <20181006183928.GA703@zn.tnic> References: <20181006001928.28097-1-andi@firstfloor.org> <20181006181506.7cycnsg5gtoavtmx@two.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Cc: Thomas Gleixner , peterz@infradead.org, x86@kernel.org, linux-kernel@vger.kernel.org, eranian@google.com, kan.liang@intel.com, isaku.yamahata@intel.com, kvm@vger.kernel.org, Andi Kleen To: Andi Kleen Return-path: Content-Disposition: inline In-Reply-To: <20181006181506.7cycnsg5gtoavtmx@two.firstfloor.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Sat, Oct 06, 2018 at 11:15:07AM -0700, Andi Kleen wrote: > The matcher can be used to match specific hardware steppings by setting > the min/max_ucode to 0 or specific microcode revisions > (which are associated with steppings) This better be explained unambiguously. > We still support the old microcode interface that allows updates > per CPU, and also it could happen during CPU hotplug. There are no per CPU microcode updates anymore - it is all or none. It is actually your microcoders who came up with a bunch of restrictions like quiescing the cores from doing *anything*, blocking hotplug, prohibiting updates if a subset of the cores is not online and still not guaranteeing it'll work all the time because . The actually very simple reason being it is just too late for microcode update when the machine is up. Where all I wanna do is rip the damn thing out completely. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.