From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: Re: [RFC PATCH 5/6] kvm: Re-introduce memslots->nmemslots Date: Thu, 06 Dec 2012 17:07:07 -0700 Message-ID: <1354838827.3124.1.camel@ul30vt.home> References: <20121203231912.3661.57179.stgit@bling.home> <20121203233936.3661.69261.stgit@bling.home> <20121205212629.GD20260@amt.cnet> <1354748573.3224.63.camel@bling.home> <20121206014507.GA9890@amt.cnet> <1354765897.3224.71.camel@bling.home> <20121206235848.GA30582@amt.cnet> <20121206235949.GA30775@amt.cnet> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, gleb@redhat.com, linux-kernel@vger.kernel.org To: Marcelo Tosatti Return-path: In-Reply-To: <20121206235949.GA30775@amt.cnet> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, 2012-12-06 at 21:59 -0200, Marcelo Tosatti wrote: > On Thu, Dec 06, 2012 at 09:58:48PM -0200, Marcelo Tosatti wrote: > > On Wed, Dec 05, 2012 at 08:51:37PM -0700, Alex Williamson wrote: > > > > > id_to_memslot seems like a good place to catch all the users since > > > > > that's the only way to get a slot from a slot id after the array is > > > > > sorted. We need to check both is the slot in bounds (EINVAL), but also > > > > > is it allocated (ENOENT). id_to_memslot could both of these if we > > > > > wanted to switch it to ERR_PTR. Thanks, > > > > > > > > > > Alex > > > > > > > > There should never be a reference to a slot out of bounds by KVM itself > > > > (BUG_ON). Only userspace can attempt a reference to such slot. > > > > > > If I understand correctly, you're saying this last chunk is unique > > > because kvm_get_dirty_log() is an internal interface and the test should > > > be restricted to callers from userspace interfaces, namely > > > kvm_vm_ioctl_get_dirty_log(). That sounds reasonable; book3s_pr seems > > > to be the only caller that relies on kvm_get_dirty_log() validating the > > > slot. Thanks, > > > > > > Alex > > > > Yep - so you can move the check to such userspace interfaces, and bug on > > on WARN otherwise (in id_to_memslot). > > WARN_ON. The point is, if its not a valid condition, it should be > explicitly so. > > > Does that make sense?? Yep, I'll add that if we decide to go that route. This patch isn't necessary with the series I just posted since the array is still static. Thanks, Alex