From 137e5531351db258eff58ea28f4dc8fdf7ca2990 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Tue, 24 Mar 2020 09:28:28 -0600 Subject: [PATCH] vfio/pci: Add sriov_configure support With the VF Token interface we can now expect that a vfio userspace driver must be in collaboration with the PF driver, an unwitting userspace driver will not be able to get past the GET_DEVICE_FD step in accessing the device. We can now move on to actually allowing SR-IOV to be enabled by vfio-pci on the PF. Support for this is not enabled by default in this commit, but it does provide a module option for this to be enabled (enable_sriov=1). Enabling VFs is rather straightforward, except we don't want to risk that a VF might get autoprobed and bound to other drivers, so a bus notifier is used to "capture" VFs to vfio-pci using the driver_override support. We assume any later action to bind the device to other drivers is condoned by the system admin and allow it with a log warning. vfio-pci will disable SR-IOV on a PF before releasing the device, allowing a VF driver to be assured other drivers cannot take over the PF and that any other userspace driver must know the shared VF token. This support also does not provide a mechanism for the PF userspace driver itself to manipulate SR-IOV through the vfio API. With this patch SR-IOV can only be enabled via the host sysfs interface and the PF driver user cannot create or remove VFs. Reviewed-by: Cornelia Huck Reviewed-by: Kevin Tian Signed-off-by: Alex Williamson --- drivers/vfio/pci/vfio_pci.c | 106 ++++++++++++++++++++++++++++++++---- drivers/vfio/pci/vfio_pci_private.h | 2 + 2 files changed, 97 insertions(+), 11 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 6c28860..df6bae7 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -54,6 +54,12 @@ module_param(disable_idle_d3, bool, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(disable_idle_d3, "Disable using the PCI D3 low power state for idle, unused devices"); +static bool enable_sriov; +#ifdef CONFIG_PCI_IOV +module_param(enable_sriov, bool, 0644); +MODULE_PARM_DESC(enable_sriov, "Enable support for SR-IOV configuration. Enabling SR-IOV on a PF typically requires support of the userspace PF driver, enabling VFs without such support may result in non-functional VFs or PF."); +#endif + static inline bool vfio_vga_disabled(void) { #ifdef CONFIG_VFIO_PCI_VGA @@ -1535,6 +1541,35 @@ static const struct vfio_device_ops vfio_pci_ops = { static int vfio_pci_reflck_attach(struct vfio_pci_device *vdev); static void vfio_pci_reflck_put(struct vfio_pci_reflck *reflck); +static struct pci_driver vfio_pci_driver; + +static int vfio_pci_bus_notifier(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct vfio_pci_device *vdev = container_of(nb, + struct vfio_pci_device, nb); + struct device *dev = data; + struct pci_dev *pdev = to_pci_dev(dev); + struct pci_dev *physfn = pci_physfn(pdev); + + if (action == BUS_NOTIFY_ADD_DEVICE && + pdev->is_virtfn && physfn == vdev->pdev) { + pci_info(vdev->pdev, "Captured SR-IOV VF %s driver_override\n", + pci_name(pdev)); + pdev->driver_override = kasprintf(GFP_KERNEL, "%s", + vfio_pci_ops.name); + } else if (action == BUS_NOTIFY_BOUND_DRIVER && + pdev->is_virtfn && physfn == vdev->pdev) { + struct pci_driver *drv = pci_dev_driver(pdev); + + if (drv && drv != &vfio_pci_driver) + pci_warn(vdev->pdev, + "VF %s bound to driver %s while PF bound to vfio-pci\n", + pci_name(pdev), drv->name); + } + + return 0; +} static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) { @@ -1546,12 +1581,12 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) return -EINVAL; /* - * Prevent binding to PFs with VFs enabled, this too easily allows - * userspace instance with VFs and PFs from the same device, which - * cannot work. Disabling SR-IOV here would initiate removing the - * VFs, which would unbind the driver, which is prone to blocking - * if that VF is also in use by vfio-pci. Just reject these PFs - * and let the user sort it out. + * Prevent binding to PFs with VFs enabled, the VFs might be in use + * by the host or other users. We cannot capture the VFs if they + * already exist, nor can we track VF users. Disabling SR-IOV here + * would initiate removing the VFs, which would unbind the driver, + * which is prone to blocking if that VF is also in use by vfio-pci. + * Just reject these PFs and let the user sort it out. */ if (pci_num_vf(pdev)) { pci_warn(pdev, "Cannot bind to PF with SR-IOV enabled\n"); @@ -1599,6 +1634,18 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) kfree(vdev); return -ENOMEM; } + + vdev->nb.notifier_call = vfio_pci_bus_notifier; + ret = bus_register_notifier(&pci_bus_type, &vdev->nb); + if (ret) { + kfree(vdev->vf_token); + vfio_pci_reflck_put(vdev->reflck); + vfio_del_group_dev(&pdev->dev); + vfio_iommu_group_put(group, &pdev->dev); + kfree(vdev); + return ret; + } + mutex_init(&vdev->vf_token->lock); uuid_gen(&vdev->vf_token->uuid); } @@ -1632,6 +1679,8 @@ static void vfio_pci_remove(struct pci_dev *pdev) { struct vfio_pci_device *vdev; + pci_disable_sriov(pdev); + vdev = vfio_del_group_dev(&pdev->dev); if (!vdev) return; @@ -1642,6 +1691,9 @@ static void vfio_pci_remove(struct pci_dev *pdev) kfree(vdev->vf_token); } + if (vdev->nb.notifier_call) + bus_unregister_notifier(&pci_bus_type, &vdev->nb); + vfio_pci_reflck_put(vdev->reflck); vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev); @@ -1690,16 +1742,48 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev, return PCI_ERS_RESULT_CAN_RECOVER; } +static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn) +{ + struct vfio_pci_device *vdev; + struct vfio_device *device; + int ret = 0; + + might_sleep(); + + if (!enable_sriov) + return -ENOENT; + + device = vfio_device_get_from_dev(&pdev->dev); + if (!device) + return -ENODEV; + + vdev = vfio_device_data(device); + if (!vdev) { + vfio_device_put(device); + return -ENODEV; + } + + if (nr_virtfn == 0) + pci_disable_sriov(pdev); + else + ret = pci_enable_sriov(pdev, nr_virtfn); + + vfio_device_put(device); + + return ret < 0 ? ret : nr_virtfn; +} + static const struct pci_error_handlers vfio_err_handlers = { .error_detected = vfio_pci_aer_err_detected, }; static struct pci_driver vfio_pci_driver = { - .name = "vfio-pci", - .id_table = NULL, /* only dynamic ids */ - .probe = vfio_pci_probe, - .remove = vfio_pci_remove, - .err_handler = &vfio_err_handlers, + .name = "vfio-pci", + .id_table = NULL, /* only dynamic ids */ + .probe = vfio_pci_probe, + .remove = vfio_pci_remove, + .sriov_configure = vfio_pci_sriov_configure, + .err_handler = &vfio_err_handlers, }; static DEFINE_MUTEX(reflck_lock); diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h index 76c11c9..36ec690 100644 --- a/drivers/vfio/pci/vfio_pci_private.h +++ b/drivers/vfio/pci/vfio_pci_private.h @@ -13,6 +13,7 @@ #include #include #include +#include #ifndef VFIO_PCI_PRIVATE_H #define VFIO_PCI_PRIVATE_H @@ -130,6 +131,7 @@ struct vfio_pci_device { struct mutex ioeventfds_lock; struct list_head ioeventfds_list; struct vfio_pci_vf_token *vf_token; + struct notifier_block nb; }; #define is_intx(vdev) (vdev->irq_type == VFIO_PCI_INTX_IRQ_INDEX) -- 2.7.4