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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 <cohuck@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2020-03-24 09:28:28 -06:00
parent 43eeeecc8e
commit 137e553135
2 changed files with 97 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

106
drivers/vfio/pci/vfio_pci.c
View File

@ -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);

2
drivers/vfio/pci/vfio_pci_private.h
View File

@ -13,6 +13,7 @@
#include <linux/irqbypass.h>
#include <linux/types.h>
#include <linux/uuid.h>
#include <linux/notifier.h>
#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)