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[176.36.245.220]) by smtp.gmail.com with ESMTPSA id k22sm184211ljm.18.2021.09.22.03.14.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 22 Sep 2021 03:14:25 -0700 (PDT) From: Oleksandr Andrushchenko To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: boris.ostrovsky@oracle.com, jgross@suse.com, julien@xen.org, sstabellini@kernel.org, jbeulich@suse.com, Oleksandr Andrushchenko Subject: [PATCH 2/2] xen-pciback: prepare for the split for stub and PV Date: Wed, 22 Sep 2021 13:14:22 +0300 Message-Id: <20210922101422.2319240-2-andr2000@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210922101422.2319240-1-andr2000@gmail.com> References: <20210922101422.2319240-1-andr2000@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleksandr Andrushchenko Currently PCI backend implements multiple functionalities at a time. To name a few: 1. it is used as a database for assignable PCI devices, e.g. xl pci-assignable-{add|remove|list} manipulates that list. So, whenever the toolstack needs to know which PCI devices can be passed through it reads that from the relevant sysfs entries of the pciback. 2. it is used to hold the unbound PCI devices list, e.g. when passing through a PCI device it needs to be unbound from the relevant device driver and bound to pciback (strictly speaking it is not required that the device is bound to pciback, but pciback is again used as a database of the passed through PCI devices, so we can re-bind the devices back to their original drivers when guest domain shuts down) 3. device reset for the devices being passed through 4. para-virtualized use-cases support The para-virtualized part of the driver is not always needed as some architectures, e.g. Arm or x86 PVH Dom0, are not using backend-frontend model for PCI device passthrough. For such use-cases make the very first step in splitting the xen-pciback driver into two parts: extended PCI stub and PCI PV backend drivers. At the moment x86 platform will continue using CONFIG_XEN_PCIDEV_BACKEND for the fully featured backend driver and new platforms may build a driver with limited functionality (no PV) by enabling CONFIG_XEN_PCIDEV_STUB. Signed-off-by: Oleksandr Andrushchenko --- New in v2 --- drivers/xen/Kconfig | 26 +++++++++++++++++++++++++- drivers/xen/Makefile | 2 +- drivers/xen/xen-pciback/Makefile | 1 + drivers/xen/xen-pciback/pciback.h | 5 +++++ drivers/xen/xen-pciback/xenbus.c | 6 +++++- 5 files changed, 37 insertions(+), 3 deletions(-) diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index 057ddf61ef61..6e92c6be19f1 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -180,10 +180,34 @@ config SWIOTLB_XEN select DMA_OPS select SWIOTLB +config XEN_PCI_STUB + bool + +config XEN_PCIDEV_STUB + tristate "Xen PCI-device stub driver" + depends on PCI && !X86 && XEN + depends on XEN_BACKEND + select XEN_PCI_STUB + default m + help + The PCI device stub driver provides limited version of the PCI + device backend driver without para-virtualized support for guests. + If you select this to be a module, you will need to make sure no + other driver has bound to the device(s) you want to make visible to + other guests. + + The "hide" parameter (only applicable if backend driver is compiled + into the kernel) allows you to bind the PCI devices to this module + from the default device drivers. The argument is the list of PCI BDFs: + xen-pciback.hide=(03:00.0)(04:00.0) + + If in doubt, say m. + config XEN_PCIDEV_BACKEND tristate "Xen PCI-device backend driver" - depends on PCI && XEN + depends on PCI && X86 && XEN depends on XEN_BACKEND + select XEN_PCI_STUB default m help The PCI device backend driver allows the kernel to export arbitrary diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile index 3434593455b2..5aae66e638a7 100644 --- a/drivers/xen/Makefile +++ b/drivers/xen/Makefile @@ -24,7 +24,7 @@ obj-$(CONFIG_XEN_SYS_HYPERVISOR) += sys-hypervisor.o obj-$(CONFIG_XEN_PVHVM_GUEST) += platform-pci.o obj-$(CONFIG_SWIOTLB_XEN) += swiotlb-xen.o obj-$(CONFIG_XEN_MCE_LOG) += mcelog.o -obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback/ +obj-$(CONFIG_XEN_PCI_STUB) += xen-pciback/ obj-$(CONFIG_XEN_PRIVCMD) += xen-privcmd.o obj-$(CONFIG_XEN_ACPI_PROCESSOR) += xen-acpi-processor.o obj-$(CONFIG_XEN_EFI) += efi.o diff --git a/drivers/xen/xen-pciback/Makefile b/drivers/xen/xen-pciback/Makefile index e8d981d43235..e2cb376444a6 100644 --- a/drivers/xen/xen-pciback/Makefile +++ b/drivers/xen/xen-pciback/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0 obj-$(CONFIG_XEN_PCIDEV_BACKEND) += xen-pciback.o +obj-$(CONFIG_XEN_PCIDEV_STUB) += xen-pciback.o xen-pciback-y := pci_stub.o pciback_ops.o xenbus.o xen-pciback-y += conf_space.o conf_space_header.o \ diff --git a/drivers/xen/xen-pciback/pciback.h b/drivers/xen/xen-pciback/pciback.h index 95e28ee48d52..9a64196e831d 100644 --- a/drivers/xen/xen-pciback/pciback.h +++ b/drivers/xen/xen-pciback/pciback.h @@ -71,6 +71,11 @@ struct pci_dev *pcistub_get_pci_dev(struct xen_pcibk_device *pdev, struct pci_dev *dev); void pcistub_put_pci_dev(struct pci_dev *dev); +static inline bool xen_pcibk_pv_support(void) +{ + return IS_ENABLED(CONFIG_XEN_PCIDEV_BACKEND); +} + /* Ensure a device is turned off or reset */ void xen_pcibk_reset_device(struct pci_dev *pdev); diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c index da34ce85dc88..bde63ef677b8 100644 --- a/drivers/xen/xen-pciback/xenbus.c +++ b/drivers/xen/xen-pciback/xenbus.c @@ -743,6 +743,9 @@ const struct xen_pcibk_backend *__read_mostly xen_pcibk_backend; int __init xen_pcibk_xenbus_register(void) { + if (!xen_pcibk_pv_support()) + return 0; + xen_pcibk_backend = &xen_pcibk_vpci_backend; if (passthrough) xen_pcibk_backend = &xen_pcibk_passthrough_backend; @@ -752,5 +755,6 @@ int __init xen_pcibk_xenbus_register(void) void __exit xen_pcibk_xenbus_unregister(void) { - xenbus_unregister_driver(&xen_pcibk_driver); + if (xen_pcibk_pv_support()) + xenbus_unregister_driver(&xen_pcibk_driver); } -- 2.25.1