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

Xiang Zheng
2020-06-10T09:00:08Z

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?

> + 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...

> + 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".

> +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 ' '

> +};
> +
> +#endif /* I40E_MIG_H */
> +
>

--
Thanks,
Xiang