From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Egger Subject: Re: [PATCH 0 of 5] v2: Nested-p2m cleanups and locking changes Date: Mon, 27 Jun 2011 14:23:06 +0200 Message-ID: <4E08762A.2050801@amd.com> References: <20110627105654.GK17634@whitby.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20110627105654.GK17634@whitby.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Tim Deegan Cc: "xen-devel@lists.xensource.com" List-Id: xen-devel@lists.xenproject.org On 06/27/11 12:56, Tim Deegan wrote: > At 11:46 +0100 on 27 Jun (1309175170), Tim Deegan wrote: >> This patch series tidies up a few bits ofthe nested p2m code. >> The main thing it does is reorganize the locking so that most of the >> changes to nested p2m tables happen only under the p2m lock, and the >> nestedp2m lock is only needed to reassign p2m tables to new cr3 values. > > There are still a few things I'm not convinced about in the nested NPT > code: > > - The function that allocates new nested p2ms probably needs an > overhaul, as I said in my last email. Ack. > - The flushing policy is a bit confusing: e.g., what exactly ought to > happen when the guest sets the tlb-control bits? AFAICS the nested-p2ms > are already kept in sync with host-p2m changes, and we flush all > TLBs when we update nested-p2ms, so can we skip this extra flush? Yes, we can. > - Why is there a 10x increase in IPIs after this series? I don't see > what sequence of events sets the relevant cpumask bits to make this > happen. In patch 1 the code that sends the IPIs was outside of the loop and moved into the loop. Christoph -- ---to satisfy European Law for business letters: Advanced Micro Devices GmbH Einsteinring 24, 85689 Dornach b. Muenchen Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632