From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Krowiak Subject: Re: [PATCH v6 05/21] KVM: s390: CPU model support for AP virtualization Date: Tue, 3 Jul 2018 10:44:10 -0400 Message-ID: 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> <20180702181108.2c721a86.cohuck@redhat.com> <76165cca-b8ec-172a-4a1b-6f3514b44344@linux.ibm.com> <20180702182840.34560fed.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180702182840.34560fed.cohuck@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Cornelia Huck , Halil Pasic 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 List-ID: On 07/02/2018 12:28 PM, Cornelia Huck wrote: > On Mon, 2 Jul 2018 18:20:55 +0200 > Halil Pasic wrote: > >> On 07/02/2018 06:11 PM, Cornelia Huck wrote: >>> 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. >>> >> The other features introduced and exposed here are no different. For >> KVM_S390_VM_CPU_FEAT_AP defer exposing means defer allow_cpu_feat(); >> for the STFLE features, defer adding to FACILITIES_KVM_CPUMODEL. >> >> Anyway, I think the definition should be squashed into #6. Expose the >> features after patch #6 is in place or expose them at the end of the >> series is IMHO a matter of taste -- and I lean towards expose at the >> end of the series. > Squashing with patch 6 and enabling at the end of the series sounds > good to me as well. Consider it done. >