From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:46204 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732445AbfISU5X (ORCPT ); Thu, 19 Sep 2019 16:57:23 -0400 Subject: Re: [PATCH v4 4/4] vfio: pci: Using a device region to retrieve zPCI information References: <1567815231-17940-1-git-send-email-mjrosato@linux.ibm.com> <1567815231-17940-5-git-send-email-mjrosato@linux.ibm.com> <20190919172505.2eb075f8.cohuck@redhat.com> From: Matthew Rosato Message-ID: Date: Thu, 19 Sep 2019 16:57:10 -0400 MIME-Version: 1.0 In-Reply-To: <20190919172505.2eb075f8.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-s390-owner@vger.kernel.org List-ID: To: Cornelia Huck Cc: sebott@linux.ibm.com, gerald.schaefer@de.ibm.com, pasic@linux.ibm.com, borntraeger@de.ibm.com, walling@linux.ibm.com, linux-s390@vger.kernel.org, iommu@lists.linux-foundation.org, joro@8bytes.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com, kvm@vger.kernel.org, heiko.carstens@de.ibm.com, robin.murphy@arm.com, gor@linux.ibm.com, pmorel@linux.ibm.com On 9/19/19 11:25 AM, Cornelia Huck wrote: > On Fri, 6 Sep 2019 20:13:51 -0400 > Matthew Rosato wrote: > >> From: Pierre Morel >> >> We define a new configuration entry for VFIO/PCI, VFIO_PCI_ZDEV >> >> When the VFIO_PCI_ZDEV feature is configured we initialize >> a new device region, VFIO_REGION_SUBTYPE_ZDEV_CLP, to hold >> the information from the ZPCI device the use >> >> Signed-off-by: Pierre Morel >> Signed-off-by: Matthew Rosato >> --- >> drivers/vfio/pci/Kconfig | 7 +++ >> drivers/vfio/pci/Makefile | 1 + >> drivers/vfio/pci/vfio_pci.c | 9 ++++ >> drivers/vfio/pci/vfio_pci_private.h | 10 +++++ >> drivers/vfio/pci/vfio_pci_zdev.c | 85 +++++++++++++++++++++++++++++++++++++ >> 5 files changed, 112 insertions(+) >> create mode 100644 drivers/vfio/pci/vfio_pci_zdev.c >> >> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig >> index ac3c1dd..d4562a8 100644 >> --- a/drivers/vfio/pci/Kconfig >> +++ b/drivers/vfio/pci/Kconfig >> @@ -45,3 +45,10 @@ config VFIO_PCI_NVLINK2 >> depends on VFIO_PCI && PPC_POWERNV >> help >> VFIO PCI support for P9 Witherspoon machine with NVIDIA V100 GPUs >> + >> +config VFIO_PCI_ZDEV >> + bool "VFIO PCI Generic for ZPCI devices" >> + depends on VFIO_PCI && S390 >> + default y >> + help >> + VFIO PCI support for S390 Z-PCI devices > >>>>From that description, I'd have no idea whether I'd want that or not. > Is there any downside to enabling it? > :) Not really, you're just getting information from the hardware vs using hard-coded defaults. The only reason I could think of to turn it off would be if you wanted/needed to restore this hard-coded behavior. bool "VFIO PCI support for generic ZPCI devices" ? "Support for sharing ZPCI hardware device information between the host and guests." ? >> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile >> index f027f8a..781e080 100644 >> --- a/drivers/vfio/pci/Makefile >> +++ b/drivers/vfio/pci/Makefile >> @@ -3,5 +3,6 @@ >> vfio-pci-y := vfio_pci.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o >> vfio-pci-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o >> vfio-pci-$(CONFIG_VFIO_PCI_NVLINK2) += vfio_pci_nvlink2.o >> +vfio-pci-$(CONFIG_VFIO_PCI_ZDEV) += vfio_pci_zdev.o >> >> obj-$(CONFIG_VFIO_PCI) += vfio-pci.o >> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c >> index 703948c..b40544a 100644 >> --- a/drivers/vfio/pci/vfio_pci.c >> +++ b/drivers/vfio/pci/vfio_pci.c >> @@ -356,6 +356,15 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev) >> } >> } >> >> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV)) { >> + ret = vfio_pci_zdev_init(vdev); >> + if (ret) { >> + dev_warn(&vdev->pdev->dev, >> + "Failed to setup ZDEV regions\n"); >> + goto disable_exit; >> + } >> + } >> + >> vfio_pci_probe_mmaps(vdev); >> >> return 0; >> diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h >> index ee6ee91..08e02f5 100644 >> --- a/drivers/vfio/pci/vfio_pci_private.h >> +++ b/drivers/vfio/pci/vfio_pci_private.h >> @@ -186,4 +186,14 @@ static inline int vfio_pci_ibm_npu2_init(struct vfio_pci_device *vdev) >> return -ENODEV; >> } >> #endif >> + >> +#ifdef CONFIG_VFIO_PCI_ZDEV >> +extern int vfio_pci_zdev_init(struct vfio_pci_device *vdev); >> +#else >> +static inline int vfio_pci_zdev_init(struct vfio_pci_device *vdev) >> +{ >> + return -ENODEV; > > If you really want to have this configurable, why not just return 0 > here and skip the IS_ENABLED check above? > I agree that it functionally has the same result, but in this case I think Pierre was repeating the same thing the other init() functions here (IGD, etc) are doing. Though I guess the other cases have at least 1 other condition they care about besides IS_ENABLED... OK, I can make this change. >> +} >> +#endif >> + >> #endif /* VFIO_PCI_PRIVATE_H */ > > (...) >