Re: [RFC PATCH v4 08/10] i40e/vf_migration: VF live migration - pass-through VF first

Yan Zhao
2020-06-11T00:33:55Z

On Wed, Jun 10, 2020 at 04:59:43PM +0800, Xiang Zheng wrote:
> Hi Yan,
>
> few nits below...
>
> On 2020/5/18 10:53, Yan Zhao wrote:
> > This driver intercepts all device operations as long as it's probed
> > successfully by vfio-pci driver.
> >
> > It will process regions and irqs of its interest and then forward
> > operations to default handlers exported from vfio pci if it wishes to.
> >
> > In this patch, this driver does nothing but pass through VFs to guest
> > by calling to exported handlers from driver vfio-pci.
> >
> > Cc: Shaopeng He <shaopeng.he@intel.com>
> >
> > Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
> > ---
> > drivers/net/ethernet/intel/Kconfig | 10 ++
> > drivers/net/ethernet/intel/i40e/Makefile | 2 +
> > .../ethernet/intel/i40e/i40e_vf_migration.c | 165 ++++++++++++++++++
> > .../ethernet/intel/i40e/i40e_vf_migration.h | 59 +++++++
> > 4 files changed, 236 insertions(+)
> > create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration.c
> > create mode 100644 drivers/net/ethernet/intel/i40e/i40e_vf_migration.h
> >
> > diff --git a/drivers/net/ethernet/intel/Kconfig b/drivers/net/ethernet/intel/Kconfig
> > index ad34e4335df2..31780d9a59f1 100644
> > --- a/drivers/net/ethernet/intel/Kconfig
> > +++ b/drivers/net/ethernet/intel/Kconfig
> > @@ -264,6 +264,16 @@ config I40E_DCB
> >
> > If unsure, say N.
> >
> > +config I40E_VF_MIGRATION
> > + tristate "XL710 Family VF live migration support -- loadable modules only"
> > + depends on I40E && VFIO_PCI && m
> > + help
> > + Say m if you want to enable live migration of
> > + Virtual Functions of Intel(R) Ethernet Controller XL710
> > + Family of devices. It must be a module.
> > + This module serves as vendor module of module vfio_pci.
> > + VFs bind to module vfio_pci directly.
> > +
> > # this is here to allow seamless migration from I40EVF --> IAVF name
> > # so that CONFIG_IAVF symbol will always mirror the state of CONFIG_I40EVF
> > config IAVF
> > diff --git a/drivers/net/ethernet/intel/i40e/Makefile b/drivers/net/ethernet/intel/i40e/Makefile
> > index 2f21b3e89fd0..b80c224c2602 100644
> > --- a/drivers/net/ethernet/intel/i40e/Makefile
> > +++ b/drivers/net/ethernet/intel/i40e/Makefile
> > @@ -27,3 +27,5 @@ i40e-objs := i40e_main.o \
> > i40e_xsk.o
> >
> > i40e-$(CONFIG_I40E_DCB) += i40e_dcb.o i40e_dcb_nl.o
> > +
> > +obj-$(CONFIG_I40E_VF_MIGRATION) += i40e_vf_migration.o
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_vf_migration.c b/drivers/net/ethernet/intel/i40e/i40e_vf_migration.c
> > new file mode 100644
> > index 000000000000..96026dcf5c9d
> > --- /dev/null
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_vf_migration.c
> > @@ -0,0 +1,165 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright(c) 2013 - 2019 Intel Corporation. */
> > +
> > +#include <linux/module.h>
> > +#include <linux/device.h>
> > +#include <linux/vfio.h>
> > +#include <linux/pci.h>
> > +#include <linux/eventfd.h>
> > +#include <linux/init.h>
> > +#include <linux/kernel.h>
> > +#include <linux/sysfs.h>
> > +#include <linux/file.h>
> > +#include <linux/pci.h>
> > +
> > +#include "i40e.h"
> > +#include "i40e_vf_migration.h"
> > +
> > +#define VERSION_STRING "0.1"
> > +#define DRIVER_AUTHOR "Intel Corporation"
> > +
> > +static int i40e_vf_open(void *device_data)
> > +{
> > + struct i40e_vf_migration *i40e_vf_dev =
> > + vfio_pci_vendor_data(device_data);
> > + int ret;
> > + struct vfio_device_migration_info *mig_ctl = NULL;
> > +
>
> "mig_ctl" is not used in this function. Shouldn't this declaration be
> put into the next patch?
>
right. thanks!

> > + if (!try_module_get(THIS_MODULE))
> > + return -ENODEV;
> > +
> > + mutex_lock(&i40e_vf_dev->reflock);
> > + if (!i40e_vf_dev->refcnt) {
> > + vfio_pci_set_vendor_regions(device_data, 0);
> > + vfio_pci_set_vendor_irqs(device_data, 0);
> > + }
> > +
> > + ret = vfio_pci_open(device_data);
> > + if (ret)
> > + goto error;
> > +
> > + i40e_vf_dev->refcnt++;
> > + mutex_unlock(&i40e_vf_dev->reflock);
> > + return 0;
> > +error:
> > + if (!i40e_vf_dev->refcnt) {
> > + vfio_pci_set_vendor_regions(device_data, 0);
> > + vfio_pci_set_vendor_irqs(device_data, 0);
> > + }
> > + module_put(THIS_MODULE);
> > + mutex_unlock(&i40e_vf_dev->reflock);
> > + return ret;
> > +}
> > +
> > +void i40e_vf_release(void *device_data)
> > +{
> > + struct i40e_vf_migration *i40e_vf_dev =
> > + vfio_pci_vendor_data(device_data);
> > +
> > + mutex_lock(&i40e_vf_dev->reflock);
> > + if (!--i40e_vf_dev->refcnt) {
> > + vfio_pci_set_vendor_regions(device_data, 0);
> > + vfio_pci_set_vendor_irqs(device_data, 0);
> > + }
> > + vfio_pci_release(device_data);
> > + mutex_unlock(&i40e_vf_dev->reflock);
> > + module_put(THIS_MODULE);
> > +}
> > +
> > +static long i40e_vf_ioctl(void *device_data,
> > + unsigned int cmd, unsigned long arg)
> > +{
> > + return vfio_pci_ioctl(device_data, cmd, arg);
> > +}
> > +
> > +static ssize_t i40e_vf_read(void *device_data, char __user *buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + return vfio_pci_read(device_data, buf, count, ppos);
> > +}
> > +
> > +static ssize_t i40e_vf_write(void *device_data, const char __user *buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + return vfio_pci_write(device_data, buf, count, ppos);
> > +}
> > +
> > +static int i40e_vf_mmap(void *device_data, struct vm_area_struct *vma)
> > +{
> > + return vfio_pci_mmap(device_data, vma);
> > +}
> > +
> > +static void i40e_vf_request(void *device_data, unsigned int count)
> > +{
> > + vfio_pci_request(device_data, count);
> > +}
> > +
> > +static struct vfio_device_ops i40e_vf_device_ops_node = {
> > + .name = "i40e_vf",
> > + .open = i40e_vf_open,
> > + .release = i40e_vf_release,
> > + .ioctl = i40e_vf_ioctl,
> > + .read = i40e_vf_read,
> > + .write = i40e_vf_write,
> > + .mmap = i40e_vf_mmap,
> > + .request = i40e_vf_request,
> > +};
> > +
> > +void *i40e_vf_probe(struct pci_dev *pdev)
> > +{
> > + struct i40e_vf_migration *i40e_vf_dev = NULL;
> > + struct pci_dev *pf_dev, *vf_dev;
> > + struct i40e_pf *pf;
> > + struct i40e_vf *vf;
> > + unsigned int vf_devfn, devfn;
> > + int vf_id = -1;
> > + int i;
> > +
> > + pf_dev = pdev->physfn;
> > + pf = pci_get_drvdata(pf_dev);
> > + vf_dev = pdev;
> > + vf_devfn = vf_dev->devfn;
> > +
> > + for (i = 0; i < pci_num_vf(pf_dev); i++) {
> > + devfn = (pf_dev->devfn + pf_dev->sriov->offset +
> > + pf_dev->sriov->stride * i) & 0xff;
> > + if (devfn == vf_devfn) {
> > + vf_id = i;
> > + break;
> > + }
> > + }
> > +
> > + if (vf_id == -1)
> > + return ERR_PTR(-EINVAL);
> > +
> > + i40e_vf_dev = kzalloc(sizeof(*i40e_vf_dev), GFP_KERNEL);
> > +
> > + if (!i40e_vf_dev)
> > + return ERR_PTR(-ENOMEM);
> > +
> > + i40e_vf_dev->vf_id = vf_id;
> > + i40e_vf_dev->vf_vendor = pdev->vendor;
> > + i40e_vf_dev->vf_device = pdev->device;
> > + i40e_vf_dev->pf_dev = pf_dev;
> > + i40e_vf_dev->vf_dev = vf_dev;
> > + mutex_init(&i40e_vf_dev->reflock);
> > +
> > + vf = &pf->vf[vf_id];
> > +
>
> "vf" is also not used in this function...
>
yes, thanks.

> > + return i40e_vf_dev;
> > +}
> > +
> > +static void i40e_vf_remove(void *vendor_data)
> > +{
> > + kfree(vendor_data);
> > +}
> > +
> > +#define i40e_vf_device_ops (&i40e_vf_device_ops_node)
> > +module_vfio_pci_register_vendor_handler("I40E VF", i40e_vf_probe,
> > + i40e_vf_remove, i40e_vf_device_ops);
> > +
> > +MODULE_ALIAS("vfio-pci:8086-154c");
> > +MODULE_LICENSE("GPL v2");
> > +MODULE_INFO(supported, "Vendor driver of vfio pci to support VF live migration");
> > +MODULE_VERSION(VERSION_STRING);
> > +MODULE_AUTHOR(DRIVER_AUTHOR);
> > diff --git a/drivers/net/ethernet/intel/i40e/i40e_vf_migration.h b/drivers/net/ethernet/intel/i40e/i40e_vf_migration.h
> > new file mode 100644
> > index 000000000000..696d40601ec3
> > --- /dev/null
> > +++ b/drivers/net/ethernet/intel/i40e/i40e_vf_migration.h
> > @@ -0,0 +1,59 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/* Copyright(c) 2013 - 2019 Intel Corporation. */
> > +
> > +#ifndef I40E_MIG_H
> > +#define I40E_MIG_H
> > +
> > +#include <linux/pci.h>
> > +#include <linux/vfio.h>
> > +#include <linux/mdev.h>
> > +
> > +#include "i40e.h"
> > +#include "i40e_txrx.h"
> > +
> > +/* helper macros copied from vfio-pci */
> > +#define VFIO_PCI_OFFSET_SHIFT 40
> > +#define VFIO_PCI_OFFSET_TO_INDEX(off) ((off) >> VFIO_PCI_OFFSET_SHIFT)
> > +#define VFIO_PCI_INDEX_TO_OFFSET(index) ((u64)(index) << VFIO_PCI_OFFSET_SHIFT)
> > +#define VFIO_PCI_OFFSET_MASK (((u64)(1) << VFIO_PCI_OFFSET_SHIFT) - 1)
> > +
> > +/* Single Root I/O Virtualization */
> > +struct pci_sriov {
> > + int pos; /* Capability position */
> > + int nres; /* Number of resources */
> > + u32 cap; /* SR-IOV Capabilities */
> > + u16 ctrl; /* SR-IOV Control */
> > + u16 total_VFs; /* Total VFs associated with the PF */
> > + u16 initial_VFs; /* Initial VFs associated with the PF */
> > + u16 num_VFs; /* Number of VFs available */
> > + u16 offset; /* First VF Routing ID offset */
> > + u16 stride; /* Following VF stride */
> > + u16 vf_device; /* VF device ID */
> > + u32 pgsz; /* Page size for BAR alignment */
> > + u8 link; /* Function Dependency Link */
> > + u8 max_VF_buses; /* Max buses consumed by VFs */
> > + u16 driver_max_VFs; /* Max num VFs driver supports */
> > + struct pci_dev *dev; /* Lowest numbered PF */
> > + struct pci_dev *self; /* This PF */
> > + u32 cfg_size; /* VF config space size */
> > + u32 class; /* VF device */
> > + u8 hdr_type; /* VF header type */
> > + u16 subsystem_vendor; /* VF subsystem vendor */
> > + u16 subsystem_device; /* VF subsystem device */
> > + resource_size_t barsz[PCI_SRIOV_NUM_BARS]; /* VF BAR size */
> > + bool drivers_autoprobe; /* Auto probing of VFs by driver */
> > +};
> > +
>
> Can "struct pci_sriov" be extracted for common use? This should not be exclusive
> for "i40e_vf migration support".
>
the definition of this structure is actually in driver/pci/pci.h.
maybe removing the copy here and use below include is better?
#include "../../../../pci/pci.h"

> > +struct i40e_vf_migration {
> > + __u32 vf_vendor;
> > + __u32 vf_device;
> > + __u32 handle;
> > + struct pci_dev *pf_dev;
> > + struct pci_dev *vf_dev;
> > + int vf_id;
> > + int refcnt;
> > + struct mutex reflock; /*mutex protect refcnt */
> ^ ^
>
> stray ' '
>
got it!

thanks for review.

Yan
> > +};
> > +
> > +#endif /* I40E_MIG_H */
> > +
> >
>
> --
> Thanks,
> Xiang
>