Re: [PATCH 4/5] PCI: Add max_vfs in sysfs per pci device where supports

Konrad Rzeszutek Wilk
2012-10-04T14:26:34Z

On Wed, Oct 03, 2012 at 10:51:34AM -0700, Yinghai Lu wrote:
> only pci device that support sriov will have max_vfs show up in /sys
^-Only ^-devices ^-SRIOV

>
> when user set value in /sys, driver ops set_max_vfs will be called to enable
> VF there.

Huh? What value? What are they enabling? Your comment makes it sound as
if setting any value (say '0xdeadbeef') will be called to enable a VF.

I don't think that is what the code does. Can you explain what the
proper values are to be submitted to the SysFS value 'max_vfs' and
what the kernel ought to be doing? Perhaps include a little snippet
from the kernel log so if somebody has a bug they can look at see
what you got and can compare?

Thank you.
>
> Signed-off-by: Yinghai Lu <yinghai@kernel.org>
> ---
> drivers/pci/pci-sysfs.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/pci.h | 1 +
> 2 files changed, 52 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
> index fbbb97f..9b6f409 100644
> --- a/drivers/pci/pci-sysfs.c
> +++ b/drivers/pci/pci-sysfs.c
> @@ -458,6 +458,52 @@ boot_vga_show(struct device *dev, struct device_attribute *attr, char *buf)
> }
> struct device_attribute vga_attr = __ATTR_RO(boot_vga);
>
> +static ssize_t
> +max_vfs_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + return sprintf(buf, "%u\n", pdev->max_vfs);
> +}
> +
> +static void max_vfs_callback(struct device *dev)
> +{
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + mutex_lock(&pci_remove_rescan_mutex);
> + if (pdev->is_added && dev->driver) {
> + struct pci_driver *pdrv;
> +
> + pdrv = to_pci_driver(dev->driver);
> + if (pdrv->set_max_vfs)
> + pdrv->set_max_vfs(pdev);
> +
> + }
> + mutex_unlock(&pci_remove_rescan_mutex);
> +}
> +static ssize_t
> +max_vfs_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + unsigned long val;
> + int err;
> + struct pci_dev *pdev = to_pci_dev(dev);
> +
> + if (kstrtoul(buf, 0, &val) < 0)
> + return -EINVAL;
> +
> + pdev->max_vfs = val;
> +
> + err = device_schedule_callback(dev, max_vfs_callback);
> +
> + if (err)
> + return err;
> +
> + return count;
> +}
> +struct device_attribute max_vfs_attr =
> + __ATTR(max_vfs, 0644, max_vfs_show, max_vfs_store);
> +
> static void
> pci_config_pm_runtime_get(struct pci_dev *pdev)
> {
> @@ -1405,6 +1451,7 @@ late_initcall(pci_sysfs_init);
>
> static struct attribute *pci_dev_dev_attrs[] = {
> &vga_attr.attr,
> + &max_vfs_attr.attr,
> NULL,
> };
>
> @@ -1418,6 +1465,10 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj,
> if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
> return 0;
>
> + if (a == &max_vfs_attr.attr)
> + if (!pdev->is_physfn)
> + return 0;
> +
> return a->mode;
> }
>
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 7d70a5e..f7423d4 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -335,6 +335,7 @@ struct pci_dev {
> unsigned int broken_intx_masking:1;
> unsigned int io_window_1k:1; /* Intel P2P bridge 1K I/O windows */
> pci_dev_flags_t dev_flags;
> + unsigned int max_vfs;
> atomic_t enable_cnt; /* pci_enable_device has been called */
>
> u32 saved_config_space[16]; /* config space saved at suspend time */
> --
> 1.7.7
>
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