From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH] VMX: wbinvd when vmentry under UC Date: Fri, 29 Nov 2013 14:24:40 +0000 Message-ID: <5298A3A8.6030409@citrix.com> References: <52937D2C.2050900@citrix.com> <52938D0C0200007800106D24@nat28.tlf.novell.com> <96EC5A4F3149B74492D2D9B9B1602C2734838CF7@ORSMSX105.amr.corp.intel.com> <5297520202000078000A7FF5@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "Liu, Jinsong" Cc: "keir@xen.org" , Jan Beulich , "Nakajima, Jun" , "tim@xen.org" , "Dong, Eddie" , "zhenzhong.duan@oracle.com" , "Dugger, Donald D" , "xen-devel@lists.xen.org" , "Auld, Will" , "suravee.suthikulpanit@amd.com" , "sherry.hurwitz@amd.com" , "Zhang, Xiantao" List-Id: xen-devel@lists.xenproject.org On 29/11/13 14:15, Liu, Jinsong wrote: > Jan Beulich wrote: >>>>> "Liu, Jinsong" 11/28/13 8:17 AM >>> >>> Liu, Jinsong wrote: >>>> Yes. reprogram_timer here just delay timer a little slot, say, >>>> 1~2ms. I think it's OK, i.e. at any point of wbinvd() operation at >>>> hypervisor, or any irq disabled area, timer interrupt in fact also >>>> has good chance to be delayed some time -- however at TIMER_SOFTIRQ, >>>> all expired thing would be executed, and re-calculated and set next >>>> time point via reprogram_timer -- that's OK. >>> Comments/thoughts about this option? >> Apart from continuing to be very uncertain that this won't have any >> bad side effects, I'm also rather concerned that you deal with one >> special case interrupt here, ignoring other potentially high rate ones >> (like such coming from NICs). >> >> Jan > Considering this, seems adding flag is the only work around way since high freq interrupt would result in dead-like-loop. My concern of adding flag is it's not easy to clean every possible path, especially future extension. > > Or, do not support vt-d w/o snoop. > > Thanks, > Jinsong Do you know how many systems have vt-d without snoop ? ~Andrew