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Fri, 10 Dec 2021 08:36:29 +0000 (GMT) Received: from sig-9-145-163-175.de.ibm.com (unknown [9.145.163.175]) by b06wcsmtp001.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 10 Dec 2021 08:36:29 +0000 (GMT) Message-ID: Subject: Re: [PATCH 14/32] KVM: s390: pci: do initial setup for AEN interpretation From: Niklas Schnelle To: Matthew Rosato , Christian Borntraeger , linux-s390@vger.kernel.org Cc: alex.williamson@redhat.com, cohuck@redhat.com, farman@linux.ibm.com, pmorel@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, gerald.schaefer@linux.ibm.com, agordeev@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com, vneethv@linux.ibm.com, oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 10 Dec 2021 09:36:29 +0100 In-Reply-To: <31980a07-e2e8-cef3-f0b4-370dad4cb14c@linux.ibm.com> References: <20211207205743.150299-1-mjrosato@linux.ibm.com> <20211207205743.150299-15-mjrosato@linux.ibm.com> <596857e3-ab13-7513-eeda-ed407fe22732@linux.ibm.com> <31980a07-e2e8-cef3-f0b4-370dad4cb14c@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-16.el8) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: toWC4W74o5bzcLAcc3TR0xGgU_7EsKtc X-Proofpoint-GUID: 5qo78H_0h78S6eR4H29CDSe9yDRDJF7C X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-10_03,2021-12-08_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 spamscore=0 mlxscore=0 priorityscore=1501 phishscore=0 bulkscore=0 malwarescore=0 impostorscore=0 clxscore=1015 mlxlogscore=999 adultscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112100047 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-12-09 at 15:20 -0500, Matthew Rosato wrote: > On 12/9/21 2:54 PM, Christian Borntraeger wrote: > > Am 07.12.21 um 21:57 schrieb Matthew Rosato: > > > Initial setup for Adapter Event Notification Interpretation for zPCI > > > passthrough devices. Specifically, allocate a structure for > > > forwarding of > > > adapter events and pass the address of this structure to firmware. > > > > > > Signed-off-by: Matthew Rosato > > > --- > > > arch/s390/include/asm/pci_insn.h | 12 ++++ > > > arch/s390/kvm/interrupt.c | 17 +++++ > > > arch/s390/kvm/kvm-s390.c | 3 + > > > arch/s390/kvm/pci.c | 113 +++++++++++++++++++++++++++++++ > > > arch/s390/kvm/pci.h | 42 ++++++++++++ > > > 5 files changed, 187 insertions(+) > > > create mode 100644 arch/s390/kvm/pci.h > > > ---8<--- > > > int kvm_s390_pci_dev_open(struct zpci_dev *zdev) > > > { > > > @@ -55,3 +162,9 @@ int kvm_s390_pci_attach_kvm(struct zpci_dev *zdev, > > > struct kvm *kvm) > > > return 0; > > > } > > > EXPORT_SYMBOL_GPL(kvm_s390_pci_attach_kvm); > > > + > > > +void kvm_s390_pci_init(void) > > > +{ > > > + spin_lock_init(&aift.gait_lock); > > > + mutex_init(&aift.lock); > > > +} > > > > Can we maybe use designated initializer for the static definition of > > aift, e.g. something > > like > > static struct zpci_aift aift = { > > .gait_lock = __SPIN_LOCK_UNLOCKED(aift.gait_lock), > > .lock = __MUTEX_INITIALIZER(aift.lock), > > } > > and get rid of the init function? > > > Maybe -- I can certainly do the above, but I do add a call to > zpci_get_mdd() in the init function (patch 23), so if I want to in patch > 23 instead add .mdd = zpci_get_mdd() to this designated initializer I'd > have to re-work zpci_get_mdd (patch 12) to return the mdd rather than > the CLP LIST PCI return code. We want at least a warning if we're > setting a 0 for mdd because the CLP failed for some bizarre reason. > > I guess one option would be to move the WARN_ON into the zpci_get_mdd() > function itself and then now we can do Hmm, if we do change zpci_get_mdd() which I'm generally fine with I feel like the initializer would be weird mix of truly static lock initialization and a function that actually does a CLP. I'm also a little worried about initialization order if kvm is built- in. The CLP should work even with PCI not initialized but what if for example the facility isn't even there? Also if you do change zpci_get-mdd() I'd prefer a pr_err() instead of a WARN_ON(), no reason to crash the system for this if it runs with panic-on-warn. So I think overall keeping it as is makes more sense.