From 21ca9fb62d4688da41825e0f05d8e7e26afc69d6 Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Thu, 24 Feb 2022 16:20:10 +0200 Subject: PCI/IOV: Add pci_iov_vf_id() to get VF index 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 Acked-by: Bjorn Helgaas Signed-off-by: Yishai Hadas Signed-off-by: Leon Romanovsky --- drivers/pci/iov.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/pci') diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 0267977c9f17..2e9f3d70803a 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -33,6 +33,20 @@ int pci_iov_virtfn_devfn(struct pci_dev *dev, int vf_id) } EXPORT_SYMBOL_GPL(pci_iov_virtfn_devfn); +int pci_iov_vf_id(struct pci_dev *dev) +{ + struct pci_dev *pf; + + if (!dev->is_virtfn) + return -EINVAL; + + pf = pci_physfn(dev); + return (((dev->bus->number << 8) + dev->devfn) - + ((pf->bus->number << 8) + pf->devfn + pf->sriov->offset)) / + pf->sriov->stride; +} +EXPORT_SYMBOL_GPL(pci_iov_vf_id); + /* * Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may * change when NumVFs changes. -- cgit v1.2.3-59-g8ed1b From a7e9f240c0da4fb73a353c603daf4beba04c6ecf Mon Sep 17 00:00:00 2001 From: Jason Gunthorpe Date: Thu, 24 Feb 2022 16:20:13 +0200 Subject: PCI/IOV: Add pci_iov_get_pf_drvdata() to allow VF reaching the drvdata of a PF 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 Acked-by: Bjorn Helgaas Signed-off-by: Yishai Hadas Signed-off-by: Leon Romanovsky --- drivers/pci/iov.c | 29 +++++++++++++++++++++++++++++ include/linux/pci.h | 7 +++++++ 2 files changed, 36 insertions(+) (limited to 'drivers/pci') diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 2e9f3d70803a..28ec952e1221 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -47,6 +47,35 @@ int pci_iov_vf_id(struct pci_dev *dev) } EXPORT_SYMBOL_GPL(pci_iov_vf_id); +/** + * pci_iov_get_pf_drvdata - Return the drvdata of a PF + * @dev - VF pci_dev + * @pf_driver - Device driver required to own the PF + * + * This must be called from a context that ensures that a VF driver is attached. + * The value returned is invalid once the VF driver completes its remove() + * callback. + * + * Locking is achieved by the driver core. A VF driver cannot be probed until + * pci_enable_sriov() is called and pci_disable_sriov() does not return until + * all VF drivers have completed their remove(). + * + * The PF driver must call pci_disable_sriov() before it begins to destroy the + * drvdata. + */ +void *pci_iov_get_pf_drvdata(struct pci_dev *dev, struct pci_driver *pf_driver) +{ + struct pci_dev *pf_dev; + + if (!dev->is_virtfn) + return ERR_PTR(-EINVAL); + pf_dev = dev->physfn; + if (pf_dev->driver != pf_driver) + return ERR_PTR(-EINVAL); + return pci_get_drvdata(pf_dev); +} +EXPORT_SYMBOL_GPL(pci_iov_get_pf_drvdata); + /* * Per SR-IOV spec sec 3.3.10 and 3.3.11, First VF Offset and VF Stride may * change when NumVFs changes. diff --git a/include/linux/pci.h b/include/linux/pci.h index 3d4ff7b35ad1..60d423d8f0c4 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -2167,6 +2167,7 @@ void __iomem *pci_ioremap_wc_bar(struct pci_dev *pdev, int bar); int pci_iov_virtfn_bus(struct pci_dev *dev, int id); int pci_iov_virtfn_devfn(struct pci_dev *dev, int id); int pci_iov_vf_id(struct pci_dev *dev); +void *pci_iov_get_pf_drvdata(struct pci_dev *dev, struct pci_driver *pf_driver); int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn); void pci_disable_sriov(struct pci_dev *dev); @@ -2200,6 +2201,12 @@ static inline int pci_iov_vf_id(struct pci_dev *dev) return -ENOSYS; } +static inline void *pci_iov_get_pf_drvdata(struct pci_dev *dev, + struct pci_driver *pf_driver) +{ + return ERR_PTR(-EINVAL); +} + static inline int pci_enable_sriov(struct pci_dev *dev, int nr_virtfn) { return -ENODEV; } -- cgit v1.2.3-59-g8ed1b From 8d26c4328b468e449df21314ef993eeaefc0306f Mon Sep 17 00:00:00 2001 From: Leon Romanovsky Date: Mon, 7 Mar 2022 13:33:25 +0200 Subject: PCI/IOV: Fix wrong kernel-doc identifier 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 Signed-off-by: Leon Romanovsky Acked-by: Randy Dunlap Acked-by: Bjorn Helgaas Link: https://lore.kernel.org/r/8cecf7df45948a256dc56148cf9e87b2f2bb4198.1646652504.git.leonro@nvidia.com Signed-off-by: Alex Williamson --- drivers/pci/iov.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/pci') diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c index 28ec952e1221..952217572113 100644 --- a/drivers/pci/iov.c +++ b/drivers/pci/iov.c @@ -49,8 +49,8 @@ EXPORT_SYMBOL_GPL(pci_iov_vf_id); /** * pci_iov_get_pf_drvdata - Return the drvdata of a PF - * @dev - VF pci_dev - * @pf_driver - Device driver required to own the PF + * @dev: VF pci_dev + * @pf_driver: Device driver required to own the PF * * This must be called from a context that ensures that a VF driver is attached. * The value returned is invalid once the VF driver completes its remove() -- cgit v1.2.3-59-g8ed1b