Messages in this thread | | | Subject | Re: [PATCH v6 05/21] KVM: s390: CPU model support for AP virtualization | From | Tony Krowiak <> | Date | Tue, 3 Jul 2018 10:44:10 -0400 |
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On 07/02/2018 12:28 PM, Cornelia Huck wrote: > On Mon, 2 Jul 2018 18:20:55 +0200 > Halil Pasic <pasic@linux.ibm.com> wrote: > >> On 07/02/2018 06:11 PM, Cornelia Huck wrote: >>> On Mon, 2 Jul 2018 11:54:28 -0400 >>> Tony Krowiak <akrowiak@linux.ibm.com> wrote: >>> >>>> On 07/02/2018 11:41 AM, Cornelia Huck wrote: >>>>> On Mon, 2 Jul 2018 11:37:11 -0400 >>>>> Tony Krowiak <akrowiak@linux.ibm.com> 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 <borntraeger@de.ibm.com> >>>>>>>> Reviewed-by: Halil Pasic <pasic@linux.ibm.com> >>>>>>>> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com> >>>>>>> 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.
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