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path: root/drivers/pci/iov.c (follow)
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* PCI: Use resource names in PCI log messagesPuranjay Mohan2023-12-161-2/+5
| | | | | | | | | | | Use the pci_resource_name() to get the name of the resource and use it while printing log messages. [bhelgaas: rename to match struct resource * names, also use names in other BAR messages] Link: https://lore.kernel.org/r/20211106112606.192563-3-puranjay12@gmail.com Signed-off-by: Puranjay Mohan <puranjay12@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Use pci_dev_id() to simplify the codeXiongfeng Wang2023-08-071-2/+1
| | | | | | | | | | When we have a struct pci_dev *, use pci_dev_id() instead of manually composing the ID with PCI_DEVID() from dev->bus->number and dev->devfn. [bhelgaas: commit log] Link: https://lore.kernel.org/r/20230807134858.116051-4-wangxiongfeng2@huawei.com Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Enlarge virtfn sysfs name bufferAlexey V. Vissarionov2023-01-181-1/+1
| | | | | | | | | | | | | | The sysfs link name "virtfn%u" constructed by pci_iov_sysfs_link() requires 17 bytes to contain the longest possible string. Increase VIRTFN_ID_LEN to accommodate that. Found by Linux Verification Center (linuxtesting.org) with SVACE. [bhelgaas: commit log, comment at #define] Fixes: dd7cc44d0bce ("PCI: add SR-IOV API for Physical Function driver") Link: https://lore.kernel.org/r/20221218033347.23743-1-gremlin@altlinux.org Signed-off-by: Alexey V. Vissarionov <gremlin@altlinux.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Fix wrong kernel-doc identifierLeon Romanovsky2022-03-071-2/+2
| | | | | | | | | | | | | | | | Replace "-" to be ":" in comment section to be aligned with kernel-doc format. drivers/pci/iov.c:67: warning: Function parameter or member 'dev' not described in 'pci_iov_get_pf_drvdata' drivers/pci/iov.c:67: warning: Function parameter or member 'pf_driver' not described in 'pci_iov_get_pf_drvdata' Fixes: a7e9f240c0da ("PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PF") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Link: https://lore.kernel.org/r/8cecf7df45948a256dc56148cf9e87b2f2bb4198.1646652504.git.leonro@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
* PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PFJason Gunthorpe2022-02-271-0/+29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are some cases where a SR-IOV VF driver will need to reach into and interact with the PF driver. This requires accessing the drvdata of the PF. Provide a function pci_iov_get_pf_drvdata() to return this PF drvdata in a safe way. Normally accessing a drvdata of a foreign struct device would be done using the device_lock() to protect against device driver probe()/remove() races. However, due to the design of pci_enable_sriov() this will result in a ABBA deadlock on the device_lock as the PF's device_lock is held during PF sriov_configure() while calling pci_enable_sriov() which in turn holds the VF's device_lock while calling VF probe(), and similarly for remove. This means the VF driver can never obtain the PF's device_lock. Instead use the implicit locking created by pci_enable/disable_sriov(). A VF driver can access its PF drvdata only while its own driver is attached, and the PF driver can control access to its own drvdata based on when it calls pci_enable/disable_sriov(). To use this API the PF driver will setup the PF drvdata in the probe() function. pci_enable_sriov() is only called from sriov_configure() which cannot happen until probe() completes, ensuring no VF races with drvdata setup. For removal, the PF driver must call pci_disable_sriov() in its remove function before destroying any of the drvdata. This ensures that all VF drivers are unbound before returning, fencing concurrent access to the drvdata. The introduction of a new function to do this access makes clear the special locking scheme and the documents the requirements on the PF/VF drivers using this. Link: https://lore.kernel.org/all/20220224142024.147653-5-yishaih@nvidia.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
* PCI/IOV: Add pci_iov_vf_id() to get VF indexJason Gunthorpe2022-02-271-0/+14
| | | | | | | | | | | | | | | | | | | | | The PCI core uses the VF index internally, often called the vf_id, during the setup of the VF, eg pci_iov_add_virtfn(). This index is needed for device drivers that implement live migration for their internal operations that configure/control their VFs. Specifically, mlx5_vfio_pci driver that is introduced in coming patches from this series needs it and not the bus/device/function which is exposed today. Add pci_iov_vf_id() which computes the vf_id by reversing the math that was used to create the bus/device/function. Link: https://lore.kernel.org/all/20220224142024.147653-2-yishaih@nvidia.com Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
* Revert "PCI: Use to_pci_driver() instead of pci_dev->driver"Bjorn Helgaas2021-11-111-15/+9
| | | | | | | | | | | | | | | | | | | | | | | | This reverts commit 2a4d9408c9e8b6f6fc150c66f3fef755c9e20d4a. Robert reported a NULL pointer dereference caused by the PCI core (local_pci_probe()) calling the i2c_designware_pci driver's .runtime_resume() method before the .probe() method. i2c_dw_pci_resume() depends on initialization done by i2c_dw_pci_probe(). Prior to 2a4d9408c9e8 ("PCI: Use to_pci_driver() instead of pci_dev->driver"), pci_pm_runtime_resume() avoided calling the .runtime_resume() method because pci_dev->driver had not been set yet. 2a4d9408c9e8 and b5f9c644eb1b ("PCI: Remove struct pci_dev->driver"), removed pci_dev->driver, replacing it by device->driver, which *has* been set by this time, so pci_pm_runtime_resume() called the .runtime_resume() method when it previously had not. Fixes: 2a4d9408c9e8 ("PCI: Use to_pci_driver() instead of pci_dev->driver") Link: https://lore.kernel.org/linux-i2c/CAP145pgdrdiMAT7=-iB1DMgA7t_bMqTcJL4N0=6u8kNY3EU0dw@mail.gmail.com/ Reported-by: Robert Święcki <robert@swiecki.net> Tested-by: Robert Święcki <robert@swiecki.net> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge branch 'pci/sysfs'Bjorn Helgaas2021-11-051-8/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Check for CAP_SYS_ADMIN before validating sysfs user input, not after (Krzysztof Wilczyński) - Always return -EINVAL from sysfs "store" functions for invalid user input instead of -EINVAL sometimes and -ERANGE others (Krzysztof Wilczyński) - Use kstrtobool() directly instead of the strtobool() wrapper (Krzysztof Wilczyński) * pci/sysfs: PCI: Use kstrtobool() directly, sans strtobool() wrapper PCI/sysfs: Return -EINVAL consistently from "store" functions PCI/sysfs: Check CAP_SYS_ADMIN before parsing user input # Conflicts: # drivers/pci/iov.c
| * PCI/sysfs: Return -EINVAL consistently from "store" functionsKrzysztof Wilczyński2021-09-291-8/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Most of the "store" functions that handle userspace input via sysfs return -EINVAL should the value fail validation and/or type conversion. This error code is a clear message to userspace that the value is not a valid input. However, some of the "show" functions return input parsing error codes as-is, which may be either -EINVAL or -ERANGE. The former would often be from kstrtobool(), and the latter typically from other kstr*() functions such as kstrtou8(), kstrtou32(), kstrtoint(), etc. -EINVAL is commonly returned as the error code to indicate that the value provided is invalid, but -ERANGE is not very useful in userspace. Therefore, normalize the return error code to be -EINVAL for when the validation and/or type conversion fails. Link: https://lore.kernel.org/r/20210915230127.2495723-2-kw@linux.com Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* | PCI: Use to_pci_driver() instead of pci_dev->driverUwe Kleine-König2021-10-181-9/+15
|/ | | | | | | | | | | | | | | Struct pci_driver contains a struct device_driver, so for PCI devices, it's easy to convert a device_driver * to a pci_driver * with to_pci_driver(). The device_driver * is in struct device, so we don't need to also keep track of the pci_driver * in struct pci_dev. Replace pci_dev->driver with to_pci_driver(). This is a step toward removing pci_dev->driver. [bhelgaas: split to separate patch] Link: https://lore.kernel.org/r/20211004125935.2300113-11-u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge branch 'pci/virtualization'Bjorn Helgaas2021-07-061-2/+9
|\ | | | | | | | | | | | | - Clarify error message for unbound devices (Moritz Fischer) * pci/virtualization: PCI/IOV: Clarify error message for unbound devices
| * PCI/IOV: Clarify error message for unbound devicesMoritz Fischer2021-06-101-2/+9
| | | | | | | | | | | | | | | | | | | | | | | | Be more verbose to disambiguate the error case when trying to configure SR-IOV with no driver bound vs. a driver that does not implement the .sriov_configure() callback. Link: https://lore.kernel.org/r/20210327175140.682708-1-mdf@kernel.org Reported-by: Brian Foley <bpfoley@google.com> Signed-off-by: Moritz Fischer <mdf@kernel.org> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Krzysztof Wilczyński <kw@linux.com>
* | PCI/sysfs: Use sysfs_emit() and sysfs_emit_at() in "show" functionsKrzysztof Wilczyński2021-06-041-6/+6
|/ | | | | | | | | | | | | | | | | | | | | | | The sysfs_emit() and sysfs_emit_at() functions were introduced to make it less ambiguous which function is preferred when writing to the output buffer in a device attribute's "show" callback [1]. Convert the PCI sysfs object "show" functions from sprintf(), snprintf() and scnprintf() to sysfs_emit() and sysfs_emit_at() accordingly, as the latter is aware of the PAGE_SIZE buffer and correctly returns the number of bytes written into the buffer. No functional change intended. [1] Documentation/filesystems/sysfs.rst Related commit: ad025f8e46f3 ("PCI/sysfs: Use sysfs_emit() and sysfs_emit_at() in "show" functions"). Link: https://lore.kernel.org/r/20210603000112.703037-2-kw@linux.com Signed-off-by: Krzysztof Wilczyński <kw@linux.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Logan Gunthorpe <logang@deltatee.com>
* PCI/IOV: Add sysfs MSI-X vector assignment interfaceLeon Romanovsky2021-04-041-6/+96
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A typical cloud provider SR-IOV use case is to create many VFs for use by guest VMs. The VFs may not be assigned to a VM until a customer requests a VM of a certain size, e.g., number of CPUs. A VF may need MSI-X vectors proportional to the number of CPUs in the VM, but there is no standard way to change the number of MSI-X vectors supported by a VF. Some Mellanox ConnectX devices support dynamic assignment of MSI-X vectors to SR-IOV VFs. This can be done by the PF driver after VFs are enabled, and it can be done without affecting VFs that are already in use. The hardware supports a limited pool of MSI-X vectors that can be assigned to the PF or to individual VFs. This is device-specific behavior that requires support in the PF driver. Add a read-only "sriov_vf_total_msix" sysfs file for the PF and a writable "sriov_vf_msix_count" file for each VF. Management software may use these to learn how many MSI-X vectors are available and to dynamically assign them to VFs before the VFs are passed through to a VM. If the PF driver implements the ->sriov_get_vf_total_msix() callback, "sriov_vf_total_msix" contains the total number of MSI-X vectors available for distribution among VFs. If no driver is bound to the VF, writing "N" to "sriov_vf_msix_count" uses the PF driver ->sriov_set_msix_vec_count() callback to assign "N" MSI-X vectors to the VF. When a VF driver subsequently reads the MSI-X Message Control register, it will see the new Table Size "N". Link: https://lore.kernel.org/linux-pci/20210314124256.70253-2-leon@kernel.org Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
* PCI/IOV: Mark VFs as not implementing PCI_COMMAND_MEMORYMatthew Rosato2020-09-211-0/+1
| | | | | | | | | | | | | | For VFs, the Memory Space Enable bit in the Command Register is hard-wired to 0. Add a new bit to signify devices where the Command Register Memory Space Enable bit does not control the device's response to MMIO accesses. Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory") Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
* s390/pci: create links between PFs and VFsNiklas Schnelle2020-05-201-3/+0
| | | | | | | | | | | | | | | | | | | | | | | On s390 PCI Virtual Functions (VFs) are scanned by firmware and are made available to Linux via the hot-plug interface. As such the common code path of doing the scan directly using the parent Physical Function (PF) is not used and fenced off with the no_vf_scan attribute. Even if the partition created the VFs itself e.g. using the sriov_numvfs attribute of a PF, the PF/VF links thus need to be established after the fact. To do this when a VF is plugged we scan through all functions on the same zbus and test whether they are the parent PF in which case we establish the necessary links. With these links established there is now no more need to fence off pci_iov_remove_virtfn() for pdev->no_vf_scan as the common code now works fine. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com> Link: https://lore.kernel.org/r/20200506154139.90609-3-schnelle@linux.ibm.com Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
* PCI/IOV: Introduce pci_iov_sysfs_link() functionNiklas Schnelle2020-05-201-11/+25
| | | | | | | | | | | | | | | | | | | Currently pci_iov_add_virtfn() scans the SR-IOV BARs, adds the VF to the bus and also creates the sysfs links between the newly added VF and its parent PF. With pdev->no_vf_scan fencing off the entire pci_iov_add_virtfn() call s390 as the sole pdev->no_vf_scan user thus ends up missing these sysfs links which are required for example by QEMU/libvirt. Instead of duplicating the code refactor pci_iov_add_virtfn() to make sysfs link creation callable separately. Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com> Link: https://lore.kernel.org/r/20200506154139.90609-1-schnelle@linux.ibm.com Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
* PCI/IOV: Fix memory leak in pci_iov_add_virtfn()Navid Emamdoost2019-12-091-5/+4
| | | | | | | | | | | In the implementation of pci_iov_add_virtfn() the allocated virtfn is leaked if pci_setup_device() fails. The error handling is not calling pci_stop_and_remove_bus_device(). Change the goto label to failed2. Fixes: 156c55325d30 ("PCI: Check for pci_setup_device() failure in pci_iov_add_virtfn()") Link: https://lore.kernel.org/r/20191125195255.23740-1-navid.emamdoost@gmail.com Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge branch 'pci/trivial'Bjorn Helgaas2019-11-281-1/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Fix typos and comments (Bjorn Helgaas) - Fix Kconfig whitespace errors (Krzysztof Kozlowski) * pci/trivial: PCI: Fix indentation PCI: Fix typos PCI: Remove useless comments and tidy others PCI: Remove unnecessary includes # Conflicts: # drivers/pci/probe.c
| * PCI: Remove unnecessary includesBjorn Helgaas2019-10-171-1/+0
| | | | | | | | | | | | Remove unnecessary includes. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* | PCI/IOV: Serialize sysfs sriov_numvfs reads vs writesPierre Crégut2019-10-151-1/+7
|/ | | | | | | | | | | | | | | | | When sriov_numvfs is being updated, we call the driver->sriov_configure() function, which may enable VFs and call probe functions, which may make new devices visible. This all happens before before sriov_numvfs_store() updates sriov->num_VFs, so previously, concurrent sysfs reads of sriov_numvfs returned stale values. Serialize the sysfs read vs the write so the read returns the correct num_VFs value. [bhelgaas: hold device_lock instead of checking mutex_is_locked()] Link: https://bugzilla.kernel.org/show_bug.cgi?id=202991 Link: https://lore.kernel.org/r/20190911072736.32091-1-pierre.cregut@orange.com Signed-off-by: Pierre Crégut <pierre.cregut@orange.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge branch 'pci/resource'Bjorn Helgaas2019-09-231-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Convert pci_resource_to_user() to a weak function to remove HAVE_ARCH_PCI_RESOURCE_TO_USER #defines (Denis Efremov) - Use PCI_SRIOV_NUM_BARS for idiomatic loop structure (Denis Efremov) - Fix Resizable BAR size suspend/restore for 1MB BARs (Sumit Saxena) - Correct "pci=resource_alignment" example in documentation (Alexey Kardashevskiy) * pci/resource: PCI: Correct pci=resource_alignment parameter example PCI: Restore Resizable BAR size bits correctly for 1MB BARs PCI: Use PCI_SRIOV_NUM_BARS in loops instead of PCI_IOV_RESOURCE_END PCI: Convert pci_resource_to_user() to a weak function # Conflicts: # drivers/pci/pci.c
| * PCI: Use PCI_SRIOV_NUM_BARS in loops instead of PCI_IOV_RESOURCE_ENDDenis Efremov2019-08-081-2/+2
| | | | | | | | | | | | | | | | | | | | Writing loop conditions as "i < NUM" is a common C idiom; using "i <= END" is unusual and thus prone to errors. Change loops to use the former. Link: https://lore.kernel.org/r/20190806140715.19847-1-efremov@linux.com Signed-off-by: Denis Efremov <efremov@linux.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
* | PCI/IOV: Remove group write permission from sriov_numvfs, ↵Kelsey Skunberg2019-09-051-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sriov_drivers_autoprobe Previously the sriov_numvfs and sriov_drivers_autoprobe sysfs files had 0664 permissions, which allowed group write. libvirt runs as root when dealing with PCI, and it chowns files needed by qemu, so group write permission should not be needed. Change these permissions from 0664 to 0644, which is what DEVICE_ATTR_RW() does by default. [bhelgaas: commit log] Link: https://lore.kernel.org/r/20190905063226.43269-1-skunberg.kelsey@gmail.com Link: https://lore.kernel.org/r/850cf536-0b72-d78c-efaf-855dcb391087@redhat.com Signed-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Acked-by: Donald Dutile <ddutile@redhat.com>
* | PCI/IOV: Move sysfs SR-IOV functions to iov.cKelsey Skunberg2019-08-201-0/+168
|/ | | | | | | | | | | | | | The sysfs SR-IOV functions are only needed when the kernel is built with SR-IOV support. Rather than put them in pci-sysfs.c under #ifdef CONFIG_PCI_IOV, move them to iov.c, which is only compiled when CONFIG_PCI_IOV=y. Link: https://lore.kernel.org/r/20190813204513.4790-4-skunberg.kelsey@gmail.com Signed-off-by: Kelsey Skunberg <skunberg.kelsey@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Donald Dutile <ddutile@redhat.com> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
* Revert "PCI/IOV: Use VF0 cached config space size for other VFs"Alex Williamson2019-07-031-2/+0
| | | | | | | | | | | | | | | | | | | | Revert 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for other VFs"), which attempted to cache the config space size from the first VF to re-use for subsequent VFs. The cached value was determined prior to discovering the PCIe capability on the VF, which resulted in the first VF reporting the correct config space size (4K), as it has a special case through pci_cfg_space_size(), while all the other VFs only reported 256 bytes. As this was only a performance optimization, we're better off without it. Fixes: 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for other VFs") Link: https://lore.kernel.org/r/156046663197.29869.3633634445109057665.stgit@gimli.home Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: KarimAllah Ahmed <karahmed@amazon.de> Cc: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com> Cc: Hao Zheng <yinhe@linux.alibaba.com>
* PCI/IOV: Add flag so platforms can skip VF scanningSebastian Ott2019-01-021-0/+6
| | | | | | | | | Provide a flag to skip scanning for new VFs after SR-IOV enablement. This can be set by implementations for which the VFs are already reported by other means. Signed-off-by: Sebastian Ott <sebott@linux.ibm.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* PCI/IOV: Factor out sriov_add_vfs()Sebastian Ott2019-01-021-13/+31
| | | | | | | | Provide sriov_add_vfs() as a wrapper to scan for VFs that cleans up after itself. This is just a code simplification. No functional change. Signed-off-by: Sebastian Ott <sebott@linux.ibm.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* PCI/IOV: Remove unnecessary include of <linux/pci-ats.h>Bjorn Helgaas2018-10-111-1/+0
| | | | | | | iov.c uses nothing declared in <linux/pci-ats.h>, so remove the include of it. No functional change intended. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Use VF0 cached config space size for other VFsKarimAllah Ahmed2018-10-111-0/+2
| | | | | | | | | | | Cache the config space size from VF0 and use it for all other VFs instead of reading it from the config space of each VF. We assume that it will be the same across all associated VFs. This is an optimization when enabling SR-IOV on a device with many VFs. Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> [bhelgaas: use CONFIG_PCI_IOV (not CONFIG_PCI_ATS)] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge branch 'pci/virtualization'Bjorn Helgaas2018-08-151-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - To avoid bus errors, enable PASID only if entire path supports End-End TLP prefixes (Sinan Kaya) - Unify slot and bus reset functions and remove hotplug knowledge from callers (Sinan Kaya) - Add Function-Level Reset quirks for Intel and Samsung NVMe devices to fix guest reboot issues (Alex Williamson) - Add function 1 DMA alias quirk for Marvell 88SS9183 PCIe SSD Controller (Bjorn Helgaas) * pci/virtualization: PCI: Add function 1 DMA alias quirk for Marvell 88SS9183 PCI: Delay after FLR of Intel DC P3700 NVMe PCI: Disable Samsung SM961/PM961 NVMe before FLR PCI: Export pcie_has_flr() PCI: Rename pci_try_reset_bus() to pci_reset_bus() PCI: Deprecate pci_reset_bus() and pci_reset_slot() functions PCI: Unify try slot and bus reset API PCI: Hide pci_reset_bridge_secondary_bus() from drivers IB/hfi1: Use pci_try_reset_bus() for initiating PCI Secondary Bus Reset PCI: Handle error return from pci_reset_bridge_secondary_bus() PCI/IOV: Tidy pci_sriov_set_totalvfs() PCI: Enable PASID only if entire path supports End-End TLP prefixes # Conflicts: # drivers/pci/hotplug/pciehp_hpc.c
| * PCI/IOV: Tidy pci_sriov_set_totalvfs()Bjorn Helgaas2018-07-191-2/+2
| | | | | | | | | | | | Fix minor style issues in pci_sriov_set_totalvfs(). No functional change intended. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* | PCI/IOV: Reset total_VFs limit after detaching PF driverJakub Kicinski2018-06-291-0/+16
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The TotalVFs register in the SR-IOV capability is the hardware limit on the number of VFs. A PF driver can limit the number of VFs further with pci_sriov_set_totalvfs(). When the PF driver is removed, reset any VF limit that was imposed by the driver because that limit may not apply to other drivers. Before 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0"), pci_sriov_set_totalvfs(pdev, 0) meant "we can enable TotalVFs virtual functions", and the nfp driver used that to remove the VF limit when the driver unloads. 8d85a7a4f2c9 broke that because instead of removing the VF limit, pci_sriov_set_totalvfs(pdev, 0) actually sets the limit to zero, and that limit persists even if another driver is loaded. We could fix that by making the nfp driver reset the limit when it unloads, but it seems more robust to do it in the PCI core instead of relying on the driver. The regression scenario is: nfp_pci_probe (driver 1) ... nfp_pci_remove pci_sriov_set_totalvfs(pf->pdev, 0) # limits VFs to 0 ... nfp_pci_probe (driver 2) nfp_rtsym_read_le("nfd_vf_cfg_max_vfs") # no VF limit from firmware Now driver 2 is broken because the VF limit is still 0 from driver 1. Fixes: 8d85a7a4f2c9 ("PCI/IOV: Allow PF drivers to limit total_VFs to 0") Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> [bhelgaas: changelog, rename functions] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Allow PF drivers to limit total_VFs to 0Jakub Kicinski2018-05-251-4/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | Some SR-IOV PF drivers implement .sriov_configure(), which allows user-space to enable VFs by writing the desired number of VFs to the sysfs "sriov_numvfs" file (see sriov_numvfs_store()). The PCI core limits the number of VFs to the TotalVFs advertised by the device in its SR-IOV capability. The PF driver can limit the number of VFs to even fewer (it may have pre-allocated data structures or knowledge of device limitations) by calling pci_sriov_set_totalvfs(), but previously it could not limit the VFs to 0. Change pci_sriov_get_totalvfs() so it always respects the VF limit imposed by the PF driver, even if the limit is 0. This sequence: pci_sriov_set_totalvfs(dev, 0); x = pci_sriov_get_totalvfs(dev); previously set "x" to TotalVFs from the SR-IOV capability. Now it will set "x" to 0. Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> [bhelgaas: split to separate patch] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI/IOV: Add pci_sriov_configure_simple()Alexander Duyck2018-04-241-0/+36
| | | | | | | | | | | | | | | | | | | | | | | | SR-IOV (Single Root I/O Virtualization) is an optional PCIe capability (see PCIe r4.0, sec 9). A PCIe Function with the SR-IOV capability is referred to as a PF (Physical Function). If SR-IOV is enabled on the PF, several VFs (Virtual Functions) may be created. The VFs can be individually assigned to virtual machines, which allows them to share a single hardware device while being isolated from each other. Some SR-IOV devices have resources such as queues and interrupts that must be set up in the PF before enabling the VFs, so they require a PF driver to do that. Other SR-IOV devices don't require any PF setup before enabling VFs. Add a pci_sriov_configure_simple() interface so PF drivers for such devices can use it without repeating the VF-enabling code. Tested-by: Mark Rustad <mark.d.rustad@intel.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com> [bhelgaas: changelog, comment] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Greg Rose <gvrose8192@gmail.com> Reviewed-by: Christoph Hellwig <hch@lst.de>:wq
* Merge branch 'pci/virtualization'Bjorn Helgaas2018-04-041-7/+35
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - probe for device reset support during enumeration instead of runtime (Bjorn Helgaas) - add ACS quirk for Ampere (née APM) root ports (Feng Kan) - add function 1 DMA alias quirk for Marvell 88SE9220 (Thomas Vincent-Cross) - protect device restore with device lock (Sinan Kaya) - handle failure of FLR gracefully (Sinan Kaya) - handle CRS (config retry status) after device resets (Sinan Kaya) - skip various config reads for SR-IOV VFs as an optimization (KarimAllah Ahmed) * pci/virtualization: PCI/IOV: Add missing prototypes for powerpc pcibios interfaces PCI/IOV: Use VF0 cached config registers for other VFs PCI/IOV: Skip BAR sizing for VFs PCI/IOV: Skip INTx config reads for VFs PCI: Wait for device to become ready after secondary bus reset PCI: Add a return type for pci_reset_bridge_secondary_bus() PCI: Wait for device to become ready after a power management reset PCI: Rename pci_flr_wait() to pci_dev_wait() and make it generic PCI: Handle FLR failure and allow other reset types PCI: Protect restore with device lock to be consistent PCI: Add function 1 DMA alias quirk for Marvell 88SE9220 PCI: Add ACS quirk for Ampere root ports PCI: Remove redundant probes for device reset support PCI: Probe for device reset support during enumeration Conflicts: include/linux/pci.h
| * PCI/IOV: Use VF0 cached config registers for other VFsKarimAllah Ahmed2018-03-311-7/+35
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cache some config data from VF0 and use it for all other VFs instead of reading it from the config space of each VF. We assume these items are the same across all associated VFs: Revision ID Class Code Subsystem Vendor ID Subsystem ID This is an optimization when enabling SR-IOV on a device with many VFs. Signed-off-by: KarimAllah Ahmed <karahmed@amazon.de> [bhelgaas: changelog, simplify comments, remove unused "device", test CONFIG_PCI_IOV instead of CONFIG_PCI_ATS, rename functions] Signed-off-by: Bjorn Helgaas <helgaas@kernel.org>
* | PCI: Tidy commentsBjorn Helgaas2018-03-191-5/+3
|/ | | | | | | Remove pointless comments that tell us the file name, remove blank line comments, follow multi-line comment conventions. No functional change intended. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* Merge tag 'pci-v4.16-changes' of ↵Linus Torvalds2018-02-061-5/+6
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci Pull PCI updates from Bjorn Helgaas: - skip AER driver error recovery callbacks for correctable errors reported via ACPI APEI, as we already do for errors reported via the native path (Tyler Baicar) - fix DPC shared interrupt handling (Alex Williamson) - print full DPC interrupt number (Keith Busch) - enable DPC only if AER is available (Keith Busch) - simplify DPC code (Bjorn Helgaas) - calculate ASPM L1 substate parameter instead of hardcoding it (Bjorn Helgaas) - enable Latency Tolerance Reporting for ASPM L1 substates (Bjorn Helgaas) - move ASPM internal interfaces out of public header (Bjorn Helgaas) - allow hot-removal of VGA devices (Mika Westerberg) - speed up unplug and shutdown by assuming Thunderbolt controllers don't support Command Completed events (Lukas Wunner) - add AtomicOps support for GPU and Infiniband drivers (Felix Kuehling, Jay Cornwall) - expose "ari_enabled" in sysfs to help NIC naming (Stuart Hayes) - clean up PCI DMA interface usage (Christoph Hellwig) - remove PCI pool API (replaced with DMA pool) (Romain Perier) - deprecate pci_get_bus_and_slot(), which assumed PCI domain 0 (Sinan Kaya) - move DT PCI code from drivers/of/ to drivers/pci/ (Rob Herring) - add PCI-specific wrappers for dev_info(), etc (Frederick Lawler) - remove warnings on sysfs mmap failure (Bjorn Helgaas) - quiet ROM validation messages (Alex Deucher) - remove redundant memory alloc failure messages (Markus Elfring) - fill in types for compile-time VGA and other I/O port resources (Bjorn Helgaas) - make "pci=pcie_scan_all" work for Root Ports as well as Downstream Ports to help AmigaOne X1000 (Bjorn Helgaas) - add SPDX tags to all PCI files (Bjorn Helgaas) - quirk Marvell 9128 DMA aliases (Alex Williamson) - quirk broken INTx disable on Ceton InfiniTV4 (Bjorn Helgaas) - fix CONFIG_PCI=n build by adding dummy pci_irqd_intx_xlate() (Niklas Cassel) - use DMA API to get MSI address for DesignWare IP (Niklas Cassel) - fix endpoint-mode DMA mask configuration (Kishon Vijay Abraham I) - fix ARTPEC-6 incorrect IS_ERR() usage (Wei Yongjun) - add support for ARTPEC-7 SoC (Niklas Cassel) - add endpoint-mode support for ARTPEC (Niklas Cassel) - add Cadence PCIe host and endpoint controller driver (Cyrille Pitchen) - handle multiple INTx status bits being set in dra7xx (Vignesh R) - translate dra7xx hwirq range to fix INTD handling (Vignesh R) - remove deprecated Exynos PHY initialization code (Jaehoon Chung) - fix MSI erratum workaround for HiSilicon Hip06/Hip07 (Dongdong Liu) - fix NULL pointer dereference in iProc BCMA driver (Ray Jui) - fix Keystone interrupt-controller-node lookup (Johan Hovold) - constify qcom driver structures (Julia Lawall) - rework Tegra config space mapping to increase space available for endpoints (Vidya Sagar) - simplify Tegra driver by using bus->sysdata (Manikanta Maddireddy) - remove PCI_REASSIGN_ALL_BUS usage on Tegra (Manikanta Maddireddy) - add support for Global Fabric Manager Server (GFMS) event to Microsemi Switchtec switch driver (Logan Gunthorpe) - add IDs for Switchtec PSX 24xG3 and PSX 48xG3 (Kelvin Cao) * tag 'pci-v4.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci: (140 commits) PCI: cadence: Add EndPoint Controller driver for Cadence PCIe controller dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe endpoint controller PCI: endpoint: Fix EPF device name to support multi-function devices PCI: endpoint: Add the function number as argument to EPC ops PCI: cadence: Add host driver for Cadence PCIe controller dt-bindings: PCI: cadence: Add DT bindings for Cadence PCIe host controller PCI: Add vendor ID for Cadence PCI: Add generic function to probe PCI host controllers PCI: generic: fix missing call of pci_free_resource_list() PCI: OF: Add generic function to parse and allocate PCI resources PCI: Regroup all PCI related entries into drivers/pci/Makefile PCI/DPC: Reformat DPC register definitions PCI/DPC: Add and use DPC Status register field definitions PCI/DPC: Squash dpc_rp_pio_get_info() into dpc_process_rp_pio_error() PCI/DPC: Remove unnecessary RP PIO register structs PCI/DPC: Push dpc->rp_pio_status assignment into dpc_rp_pio_get_info() PCI/DPC: Squash dpc_rp_pio_print_error() into dpc_rp_pio_get_info() PCI/DPC: Make RP PIO log size check more generic PCI/DPC: Rename local "status" to "dpc_status" PCI/DPC: Squash dpc_rp_pio_print_tlp_header() into dpc_rp_pio_print_error() ...
| * Merge branch 'pci/spdx' into nextBjorn Helgaas2018-02-011-0/+1
| |\ | | | | | | | | | | | | | | | | | | | | | | | | * pci/spdx: PCI: Add SPDX GPL-2.0+ to replace implicit GPL v2 or later statement PCI: Add SPDX GPL-2.0+ to replace GPL v2 or later boilerplate PCI: Add SPDX GPL-2.0 to replace COPYING boilerplate PCI: Add SPDX GPL-2.0 to replace GPL v2 boilerplate PCI: Add SPDX GPL-2.0 when no license was specified
| | * PCI: Add SPDX GPL-2.0 when no license was specifiedBjorn Helgaas2018-01-261-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | b24413180f56 ("License cleanup: add SPDX GPL-2.0 license identifier to files with no license") added SPDX GPL-2.0 to several PCI files that previously contained no license information. Add SPDX GPL-2.0 to all other PCI files that did not contain any license information and hence were under the default GPL version 2 license of the kernel. Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| * | PCI: Add wrappers for dev_printk()Frederick Lawler2018-01-181-5/+5
| |/ | | | | | | | | | | | | | | Add PCI-specific dev_printk() wrappers and use them to simplify the code slightly. No functional change intended. Signed-off-by: Frederick Lawler <fred@fredlawl.com> [bhelgaas: squash into one patch] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* / PCI/IOV: Add pci_vf_drivers_autoprobe() interfaceBryant G. Ly2017-12-111-0/+11
|/ | | | | | | | | | | | Add a pci_vf_drivers_autoprobe() interface. Setting autoprobe to false on the PF prevents drivers from binding to VFs when they are enabled. Signed-off-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com> Signed-off-by: Juan J. Alvarez <jjalvare@linux.vnet.ibm.com> Acked-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Russell Currey <ruscur@russell.cc> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
* PCI: Restore ARI Capable Hierarchy before setting numVFsTony Nguyen2017-10-111-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In the restore path, we previously read PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE before restoring PCI_SRIOV_CTRL_ARI: pci_restore_state pci_restore_iov_state sriov_restore_state pci_iov_set_numvfs pci_read_config_word(... PCI_SRIOV_VF_OFFSET, &iov->offset) pci_read_config_word(... PCI_SRIOV_VF_STRIDE, &iov->stride) pci_write_config_word(... PCI_SRIOV_CTRL, iov->ctrl) But per SR-IOV r1.1, sec 3.3.3.5, the device can use PCI_SRIOV_CTRL_ARI to determine PCI_SRIOV_VF_OFFSET and PCI_SRIOV_VF_STRIDE. Therefore, this path, which is used for suspend/resume and AER recovery, can corrupt iov->offset and iov->stride. Since the iov state is associated with the device, not the driver, if we reload the driver, it will use the the corrupted data, which may cause crashes like this: kernel BUG at drivers/pci/iov.c:157! RIP: 0010:pci_iov_add_virtfn+0x2eb/0x350 Call Trace: pci_enable_sriov+0x353/0x440 ixgbe_pci_sriov_configure+0xd5/0x1f0 [ixgbe] sriov_numvfs_store+0xf7/0x170 dev_attr_store+0x18/0x30 sysfs_kf_write+0x37/0x40 kernfs_fop_write+0x120/0x1b0 vfs_write+0xb5/0x1a0 SyS_write+0x55/0xc0 Restore PCI_SRIOV_CTRL_ARI before calling pci_iov_set_numvfs(), then restore the rest of PCI_SRIOV_CTRL (which may set PCI_SRIOV_CTRL_VFE) afterwards. Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> [bhelgaas: changelog, add comment, also clear ARI if necessary] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Alexander Duyck <alexander.h.duyck@intel.com> CC: Emil Tantilov <emil.s.tantilov@intel.com>
* PCI: Create SR-IOV virtfn/physfn links before attaching driverStuart Hayes2017-10-111-1/+2
| | | | | | | | | | | When creating virtual functions, create the "virtfn%u" and "physfn" links in sysfs *before* attaching the driver instead of after. When we attach the driver to the new virtual network interface first, there is a race when the driver attaches to the new sends out an "add" udev event, and the network interface naming software (biosdevname or systemd, for example) tries to look at these links. Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI: Cache the VF device ID in the SR-IOV structureFilippo Sironi2017-10-051-2/+3
| | | | | | | | Cache the VF device ID in the SR-IOV structure and use it instead of reading it over and over from the PF config space capability. Signed-off-by: Filippo Sironi <sironi@amazon.de> [bhelgaas: rename to "vf_device" to match pci_dev->device] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
* PCI: Remove reset argument from pci_iov_{add,remove}_virtfn()Jan H. Schönherr2017-10-051-13/+5
| | | | | | | | | | | The "reset" argument passed to pci_iov_add_virtfn() and pci_iov_remove_virtfn() is always zero since 46cb7b1bd86f ("PCI: Remove unused SR-IOV VF Migration support") Remove the argument together with the associated code. Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Acked-by: Russell Currey <ruscur@russell.cc>
* PCI: Disable VF decoding before pcibios_sriov_disable() updates resourcesGavin Shan2017-08-301-3/+4
| | | | | | | | | | | | | | | | | | | | | | | | A struct resource represents the address space consumed by a device. We should not modify that resource while the device is actively using the address space. For VFs, pci_iov_update_resource() enforces this by printing a warning and doing nothing if the VFE (VF Enable) and MSE (VF Memory Space Enable) bits are set. Previously, both sriov_enable() and sriov_disable() called the pcibios_sriov_disable() arch hook, which may update the struct resource, while VFE and MSE were enabled. This effectively dropped the resource update pcibios_sriov_disable() intended to do. Disable VF memory decoding before calling pcibios_sriov_disable(). Reported-by: Carol L Soto <clsoto@us.ibm.com> Tested-by: Carol L Soto <clsoto@us.ibm.com> Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> [bhelgaas: changelog] Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: shan.gavin@gmail.com Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org>
* PCI: Protect pci_driver->sriov_configure() usage with device_lock()Jakub Kicinski2017-06-151-4/+0
| | | | | | | | | | | | | | | | | | | | | Every method in struct device_driver or structures derived from it like struct pci_driver MUST provide exclusion vs the driver's ->remove() method, usually by using device_lock(). Protect use of pci_driver->sriov_configure() by holding the device lock while calling it. The PCI core sets the pci_dev->driver pointer in local_pci_probe() before calling ->probe() and only clears it after ->remove(). This means driver's ->sriov_configure() callback will happily race with probe() and remove(), most likely leading to BUGs, since drivers don't expect this. Remove the iov lock completely, since we remove the last user. [bhelgaas: changelog, thanks to Christoph for locking rule] Link: http://lkml.kernel.org/r/20170522225023.14010-1-jakub.kicinski@netronome.com Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
* PCI: Add sysfs sriov_drivers_autoprobe to control VF driver bindingBodong Wang2017-04-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | Sometimes it is not desirable to bind SR-IOV VFs to drivers. This can save host side resource usage by VF instances that will be assigned to VMs. Add a new PCI sysfs interface "sriov_drivers_autoprobe" to control that from the PF. To modify it, echo 0/n/N (disable probe) or 1/y/Y (enable probe) to: /sys/bus/pci/devices/<DOMAIN:BUS:DEVICE.FUNCTION>/sriov_drivers_autoprobe Note that this must be done before enabling VFs. The change will not take effect if VFs are already enabled. Simply, one can disable VFs by setting sriov_numvfs to 0, choose whether to probe or not, and then re-enable the VFs by restoring sriov_numvfs. [bhelgaas: changelog, ABI doc] Signed-off-by: Bodong Wang <bodong@mellanox.com> Signed-off-by: Eli Cohen <eli@mellanox.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com> Reviewed-by: Alex Williamson <alex.williamson@redhat.com>