From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: VPMU backports for 4.6 Date: Wed, 20 Jan 2016 12:36:51 -0500 Message-ID: <569FC5B3.9050304@oracle.com> References: <569FB207.7000206@oracle.com> <569FCE5E02000078000C94CC@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1aLwgZ-0005L8-HL for xen-devel@lists.xenproject.org; Wed, 20 Jan 2016 17:36:47 +0000 In-Reply-To: <569FCE5E02000078000C94CC@prv-mh.provo.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: xen-devel List-Id: xen-devel@lists.xenproject.org On 01/20/2016 12:13 PM, Jan Beulich wrote: >>>> On 20.01.16 at 17:12, wrote: >> There two patches need to be backported to 4.6 >> >> fb424bf x86/VPMU: don't allow any non-zero writes to MSR_IA32_PEBS_ENABLE >> 31af0d7 x86/VPMU: check more carefully which bits are allowed to be >> written to MSRs > "Need to be" is pretty strong for an unsupported subsystem. In fact > I had already considered those and then decided not to take them. > So with you asking for them I'm not really sure what to do... "Need to" may indeed have been a bit too much. Since there is a potential for crashing the hypervisor I think we should have those two in 4.6, even if we don't officially support VPMU. (As a side --- XSA-163 says that VPMU is "unsupported security-wise". Do we make any distinction between a feature being generally or security-wise unsupported?) -boris