From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marc Zyngier Subject: Re: [PATCH v4 08/22] KVM: arm64: ITS: Implement vgic_mmio_uaccess_write_its_iidr Date: Tue, 11 Apr 2017 11:29:41 +0100 Message-ID: <5b2a8ed0-bfc7-852b-07d8-8474aef25b2a@arm.com> References: <1490607072-21610-1-git-send-email-eric.auger@redhat.com> <1490607072-21610-9-git-send-email-eric.auger@redhat.com> <864lxzch9o.fsf@arm.com> <5f1423fd-8f73-364a-9cf7-b4310957e2fd@redhat.com> <74d62f62-c0eb-b7eb-4e3a-96b1b6d0d66d@arm.com> <42ca421f-3c36-2f67-1e39-ec071cea3649@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: "prasun.kapoor" , kvm-devel , Juan Quintela , Vijaya Kumar K , Andre Przywara , "Dr. David Alan Gilbert" , "Kumar, Vijaya" , arm-mail-list , Paolo Bonzini , "kvmarm@lists.cs.columbia.edu" , eric.auger.pro@gmail.com To: Peter Maydell , Auger Eric Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On 11/04/17 11:16, Peter Maydell wrote: > On 11 April 2017 at 11:08, Auger Eric wrote: >> On 11/04/2017 12:05, Marc Zyngier wrote: >>> On 10/04/17 16:17, Auger Eric wrote: >>>> A (v1) -> B (v1 & v2): migration OK >>>> B (v1 & v2) -> C (v1): migration NOK >>> >>> So what does IIDR report on B once the A->B migration has taken place? >>> Does it report v2? >> >> yes that was the plan > > Hmm, the IIDR value shouldn't change across a migration I think. > It's guest visible so the guest should see it still the same > value even after migration. That's my worry. But we then have a problem when this VM migrates again. How does userspace find out which ABI to use then? Thanks, M. -- Jazz is not dead. It just smells funny... From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Tue, 11 Apr 2017 11:29:41 +0100 Subject: [PATCH v4 08/22] KVM: arm64: ITS: Implement vgic_mmio_uaccess_write_its_iidr In-Reply-To: References: <1490607072-21610-1-git-send-email-eric.auger@redhat.com> <1490607072-21610-9-git-send-email-eric.auger@redhat.com> <864lxzch9o.fsf@arm.com> <5f1423fd-8f73-364a-9cf7-b4310957e2fd@redhat.com> <74d62f62-c0eb-b7eb-4e3a-96b1b6d0d66d@arm.com> <42ca421f-3c36-2f67-1e39-ec071cea3649@redhat.com> Message-ID: <5b2a8ed0-bfc7-852b-07d8-8474aef25b2a@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 11/04/17 11:16, Peter Maydell wrote: > On 11 April 2017 at 11:08, Auger Eric wrote: >> On 11/04/2017 12:05, Marc Zyngier wrote: >>> On 10/04/17 16:17, Auger Eric wrote: >>>> A (v1) -> B (v1 & v2): migration OK >>>> B (v1 & v2) -> C (v1): migration NOK >>> >>> So what does IIDR report on B once the A->B migration has taken place? >>> Does it report v2? >> >> yes that was the plan > > Hmm, the IIDR value shouldn't change across a migration I think. > It's guest visible so the guest should see it still the same > value even after migration. That's my worry. But we then have a problem when this VM migrates again. How does userspace find out which ABI to use then? Thanks, M. -- Jazz is not dead. It just smells funny...