From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: Re: [PATCH v8 21/22] KVM: s390: CPU model support for AP virtualization Date: Thu, 9 Aug 2018 10:17:21 +0200 Message-ID: <58eed530-31b3-49fe-cbd7-4d101b94daa0@redhat.com> References: <1533739472-7172-1-git-send-email-akrowiak@linux.vnet.ibm.com> <1533739472-7172-22-git-send-email-akrowiak@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <1533739472-7172-22-git-send-email-akrowiak@linux.vnet.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Tony Krowiak , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: freude@de.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, borntraeger@de.ibm.com, cohuck@redhat.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, frankja@linux.ibm.com, Tony Krowiak List-ID: On 08.08.2018 16:44, Tony Krowiak wrote: > From: Tony Krowiak > > 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. Could it happen on real HW (not frankenstein CPU models), that !AP, but STFL 12 or 15 are indicated? > > If this facility is not set for the KVM guest, then only > APQNs with an APQI less than 16 will be used by a Linux > guest regardless of the matrix configuration for the virtual > machine. This is a limitation of the Linux AP bus. > > 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 for the virtual > machine. This is a limitation of the Linux AP bus. > > Signed-off-by: Tony Krowiak > Reviewed-by: Christian Borntraeger > Reviewed-by: Halil Pasic > Tested-by: Michael Mueller > Tested-by: Farhan Ali > Signed-off-by: Christian Borntraeger > --- > arch/s390/kvm/kvm-s390.c | 7 +++++++ > arch/s390/tools/gen_facilities.c | 2 ++ > 2 files changed, 9 insertions(+), 0 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 9203f0b..7d4fe9b 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -367,6 +367,13 @@ static void kvm_s390_cpu_feat_init(void) > > if (MACHINE_HAS_ESOP) > allow_cpu_feat(KVM_S390_VM_CPU_FEAT_ESOP); > + > + /* > + * Check if AP instructions installed on host > + */ Make this a one-line comment, please. > + if (ap_instructions_available() == 0) > + allow_cpu_feat(KVM_S390_VM_CPU_FEAT_AP); > + > /* > * We need SIE support, ESOP (PROT_READ protection for gmap_shadow), > * 64bit SCAO (SCA passthrough) and IDTE (for gmap_shadow unshadowing). > diff --git a/arch/s390/tools/gen_facilities.c b/arch/s390/tools/gen_facilities.c > index 90a8c9e..a52290b 100644 > --- a/arch/s390/tools/gen_facilities.c > +++ b/arch/s390/tools/gen_facilities.c > @@ -106,6 +106,8 @@ struct facility_def { > > .name = "FACILITIES_KVM_CPUMODEL", > .bits = (int[]){ > + 12, /* AP Query Configuration Information */ > + 15, /* AP Facilities Test */ > -1 /* END */ > } > }, > -- Thanks, David / dhildenb