From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] x86/intel: Protect set_cpuidmask() against #GP faults Date: Thu, 5 Jun 2014 16:00:56 +0100 Message-ID: <53908628.60506@citrix.com> References: <1401967165-27551-1-git-send-email-andrew.cooper3@citrix.com> <53909559020000780001844E@mail.emea.novell.com> <53907D97.4050906@citrix.com> <5390A1580200007800018508@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5390A1580200007800018508@mail.emea.novell.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: Jan Beulich Cc: Yang Zhang , Kevin Tian , Xen-devel List-Id: xen-devel@lists.xenproject.org On 05/06/14 15:56, Jan Beulich wrote: >>>> On 05.06.14 at 16:24, wrote: >> On 05/06/14 15:05, Jan Beulich wrote: >>>>>> On 05.06.14 at 13:19, wrote: >>>> * Call set_cpuidmask() unconditionally so faulting-capable hardware still gets >>>> a log message indicating to the user why their command line arguments are >>>> not taking effect. >>> I don't think Intel will particularly like this part. >> Why not? > Because they try to deprecate masking in favor of CPUID faulting as > much as they can. > > Jan > And that is a very good thing. However, masking is only available SandyBridge and older (for a few generations), whereas faulting is only available on IvyBridge and newer. If the user tries setting the cpuid_mask_XXX in the hope that masking occurs, It is kind to give them an error back explaining why nothing is happening. ~Andrew