From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bandan Das Subject: Re: [PATCH v4 3/3] KVM: nVMX: Emulate EPTP switching for the L1 hypervisor Date: Wed, 12 Jul 2017 14:04:08 -0400 Message-ID: References: <20170710204936.4001-1-bsd@redhat.com> <20170710204936.4001-4-bsd@redhat.com> <2d50ebc4-9328-ce08-b55b-6a331ee13cc3@redhat.com> <20170711191334.GB3442@potion> <20170711202227.GC3442@potion> <20170712134105.GG3326@potion> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Cc: Jim Mattson , David Hildenbrand , kvm list , Paolo Bonzini , LKML To: Radim =?utf-8?B?S3LEjW3DocWZ?= Return-path: In-Reply-To: <20170712134105.GG3326@potion> ("Radim \=\?utf-8\?B\?S3LEjW3DocWZ\?\= \=\?utf-8\?B\?Iidz\?\= message of "Wed, 12 Jul 2017 15:41:05 +0200") Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Radim Krčmář writes: ... >> > Thanks, we're not here to judge the guest, but to provide a bare-metal >> > experience. :) >> >> There are certain cases where do. For example, when L2 instruction emulation >> fails we decide to kill L2 instead of injecting the error to L1 and let it handle >> that. Anyway, that's a different topic, I was just trying to point out there >> are cases kvm does a somewhat policy decision... > > Emulation failure is a KVM bug and we are too lazy to implement the > bare-metal behavior correctly, but avoiding the EPTP list bug is > actually easier than introducing it. You can make KVM simpler and > improve bare-metal emulation at the same time. We are just talking past each other here trying to impose point of views. Checking for 0 makes KVM simpler. As I said before, a 0 list_address means that the hypervisor forgot to initialize it. Feel free to show me examples where the hypervisor does indeed use a 0 address for eptp list address or anything vm specific. You disagreed and I am fine with it.