From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v6 05/21] KVM: s390: CPU model support for AP virtualization Date: Mon, 2 Jul 2018 18:11:08 +0200 Message-ID: <20180702181108.2c721a86.cohuck@redhat.com> References: <1530306683-7270-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1530306683-7270-6-git-send-email-akrowiak@linux.vnet.ibm.com> <276b5ae7-7f27-faae-1e5a-0d4c084139e9@linux.ibm.com> <20180702174103.5d1ce603.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Christian Borntraeger , Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, kwankhede@nvidia.com, bjsdjshi@linux.vnet.ibm.com, pbonzini@redhat.com, alex.williamson@redhat.com, pmorel@linux.vnet.ibm.com, alifm@linux.vnet.ibm.com, mjrosato@linux.vnet.ibm.com, jjherne@linux.vnet.ibm.com, thuth@redhat.com, pasic@linux.vnet.ibm.com, berrange@redhat.com, fiuczy@linux.vnet.ibm.com, buendgen@de.ibm.com To: Tony Krowiak Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Mon, 2 Jul 2018 11:54:28 -0400 Tony Krowiak wrote: > On 07/02/2018 11:41 AM, Cornelia Huck wrote: > > On Mon, 2 Jul 2018 11:37:11 -0400 > > Tony Krowiak wrote: > > > >> On 07/02/2018 10:38 AM, Christian Borntraeger wrote: > >>> On 06/29/2018 11:11 PM, Tony Krowiak wrote: > >>>> Introduces a new CPU model feature and two CPU model > >>>> facilities to support AP virtualization for KVM guests. > >>>> > >>>> CPU model feature: > >>>> > >>>> The KVM_S390_VM_CPU_FEAT_AP feature indicates that > >>>> AP instructions are available on the guest. This > >>>> feature will be enabled by the kernel only if the AP > >>>> instructions are installed on the linux host. This feature > >>>> must be specifically turned on for the KVM guest from > >>>> userspace to use the VFIO AP device driver for guest > >>>> access to AP devices. > >>>> > >>>> CPU model facilities: > >>>> > >>>> 1. AP Query Configuration Information (QCI) facility is installed. > >>>> > >>>> This is indicated by setting facilities bit 12 for > >>>> the guest. The kernel will not enable this facility > >>>> for the guest if it is not set on the host. This facility > >>>> must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP > >>>> feature is not installed. > >>>> > >>>> If this facility is not set for the KVM guest, then only > >>>> APQNs with an APQI less than 16 will be available to the > >>>> guest regardless of the guest's matrix configuration. This > >>>> is a limitation of the AP bus running on the guest. > >>>> > >>>> 2. AP Facilities Test facility (APFT) is installed. > >>>> > >>>> This is indicated by setting facilities bit 15 for > >>>> the guest. The kernel will not enable this facility for > >>>> the guest if it is not set on the host. This facility > >>>> must not be set by userspace if the KVM_S390_VM_CPU_FEAT_AP > >>>> feature is not installed. > >>>> > >>>> If this facility is not set for the KVM guest, then no > >>>> AP devices will be available to the guest regardless of > >>>> the guest's matrix configuration. This is a limitation > >>>> of the AP bus running under the guest. > >>>> > >>>> Reviewed-by: Christian Borntraeger > >>>> Reviewed-by: Halil Pasic > >>>> Signed-off-by: Tony Krowiak > >>> I think it probably should be at the end of the series, other than that its good. > >> If I move this to the end of the series, the very next patch checks the > >> > >> KVM_S390_VM_CPU_FEAT_AP feature? > > Introduce it here, offer it only with the last patch? > > I apologize, but I don't know what you mean by this. Are you suggesting > this patch > should only include the #define for KVM_S390_VM_CPU_FEAT_AP? Yes, just introduce the definition here (so code later in the series can refer to it) and flip the switch (offer the bit) as the final patch.