From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Roedel, Joerg" Subject: Re: [PATCH 0/6] KVM: SVM: Wrap access to intercept masks into functions Date: Wed, 1 Dec 2010 11:34:19 +0100 Message-ID: <20101201103419.GH2258@amd.com> References: <1291136641-4874-1-git-send-email-joerg.roedel@amd.com> <4CF53784.2000701@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: Marcelo Tosatti , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <4CF53784.2000701@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Tue, Nov 30, 2010 at 12:42:28PM -0500, Avi Kivity wrote: > On 11/30/2010 07:03 PM, Joerg Roedel wrote: > > Hi Avi, Hi Marcelo, > > > > this patchset wraps the access to the intercept vectors in the VMCB into > > specific functions. There are two reasons for this: > > > > 1) In the nested-svm code the effective intercept masks are > > calculated from the host and the guest intercept masks. > > Whenever KVM changes the host intercept mask while the VCPU > > is in guest-mode the effective intercept masks need to be > > re-calculated. This is nicely wrapped into these functions > > now and makes the code more robust. > > > > 2) These changes make the implementation of the upcoming > > vmcb-clean-bits feature easier and also more robust (which > > was the main reason for writing this patchset). > > > > These patches were developed on-top of the patch-set I sent yesterday. I > > tested these patches with various guests (Windows-64, Linux 32,32e and > > 64 as well as with nested-svm). > > > > Looks good. > > One potential issue is that a series of set_intercept()s causes > recalc_intercepts() to be called multiple times. If it turns out to be > a problem, we can fix it by having an intercepts dirty bit and > recalculating during guest entry if the bit is set. > > Since it's nested svm only, I doubt we'll see a problem in the short term. Yes, we can optimize it if it turns out to be a problem. I thought that these changes happen infrequently enough and that there should be no more than 2-3 bits changed per exit-entry cycle at all. Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632