From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH] KVM: MMU: Do not unconditionally read PDPTE from guest memory Date: Fri, 5 Aug 2011 12:14:23 -0300 Message-ID: <20110805151423.GA16953@amt.cnet> References: <1311842177-9542-1-git-send-email-avi@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Joerg Roedel , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:43367 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753817Ab1HEPOk (ORCPT ); Fri, 5 Aug 2011 11:14:40 -0400 Content-Disposition: inline In-Reply-To: <1311842177-9542-1-git-send-email-avi@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Jul 28, 2011 at 11:36:17AM +0300, Avi Kivity wrote: > Architecturally, PDPTEs are cached in the PDPTRs when CR3 is reloaded. > On SVM, it is not possible to implement this, but on VMX this is possible > and was indeed implemented until nested SVM changed this to unconditionally > read PDPTEs dynamically. This has noticable impact when running PAE guests. > > Fix by changing the MMU to read PDPTRs from the cache, falling back to > reading from memory for the nested MMU. > > Signed-off-by: Avi Kivity Applied, thanks.