From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jan Beulich" Subject: Re: [PATCH 4/6] libxc: expose xsaves/xgetbv1/xsavec to hvm guest Date: Tue, 21 Jul 2015 03:47:46 -0600 Message-ID: <55AE3162020000780009392B@prv-mh.provo.novell.com> References: <1437118016-25547-1-git-send-email-shuai.ruan@intel.com> <1437118016-25547-5-git-send-email-shuai.ruan@intel.com> <55A8CF380200007800092561@mail.emea.novell.com> <1F1902FEECF0C94391E82D1DBE2E72BDB34B59@shsmsx102.ccr.corp.intel.com> <55A8F94E0200007800092699@mail.emea.novell.com> <1F1902FEECF0C94391E82D1DBE2E72BDB3507B@shsmsx102.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1F1902FEECF0C94391E82D1DBE2E72BDB3507B@shsmsx102.ccr.corp.intel.com> Content-Disposition: inline List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Shuai Ruan Cc: Kevin Tian , "wei.liu2@citrix.com" , Eddie Dong , "stefano.stabellini@eu.citrix.com" , "andrew.cooper3@citrix.com" , "ian.jackson@eu.citrix.com" , "xen-devel@lists.xen.org" , Jun Nakajima , "keir@xen.org" , "Ian.Campbell@citrix.com" List-Id: xen-devel@lists.xenproject.org Please don't top post. >>> On 21.07.15 at 11:33, wrote: > Thanks for your reviews Jan. > Can you give me some suggestion on this? In PATCH03, I change hvm_cpuid > function to make sure the CPUID data can be exposed to guest when xsaves > supported. Not sure what recommendations you're after - just follow the current model of white listing what we know we can/do support. Don't pass to the guest any bits you don't know whether other code changes are going to be needed in order for a guest to safely make use of the respective feature. Jan > -----Original Message----- > From: Jan Beulich [mailto:JBeulich@suse.com] > Sent: Friday, July 17, 2015 6:47 PM > To: Ruan, Shuai > Cc: andrew.cooper3@citrix.com; Ian.Campbell@citrix.com; wei.liu2@citrix.com; > ian.jackson@eu.citrix.com; stefano.stabellini@eu.citrix.com; Dong, Eddie; > Nakajima, Jun; Tian, Kevin; xen-devel@lists.xen.org; keir@xen.org > Subject: RE: [PATCH 4/6] libxc: expose xsaves/xgetbv1/xsavec to hvm guest > >>>> On 17.07.15 at 10:10, wrote: >> Ok, Thanks Jan. >> I will add the descriptions in next version. >> >> Below is the short descriptions. >> For CPUID with eax=0xd and ecx=0x1, ebx\ecx\edx may not be zero when >> xsaves supported. Also with ecx>2, ecx\edx may not be zero. If we want >> expose xsaves to HVM guest , we should not set them to zero. >> >> So in your opinions ,is it proper to add these code here? > > Sure, provided you don't leak any bits that may become defined in the > future, and the non-zero setting of which might be inconsistent with other > CPUID data. I.e. without looking at the manual, I'd guess the above is still > a little too vague. > > Jan