On Fri, Apr 02, 2021 at 07:24:26PM -0500, Bjorn Helgaas wrote:
> Possible subject, since this adds *two* files, not just "a file":
>
> PCI/IOV: Add sysfs MSI-X vector assignment interface
Sure
>
> On Sun, Mar 14, 2021 at 02:42:53PM +0200, Leon Romanovsky wrote:
> > A typical cloud provider SR-IOV use case is to create many VFs for use by
> > guest VMs. The VFs may not be assigned to a VM until a customer requests a
> > VM of a certain size, e.g., number of CPUs. A VF may need MSI-X vectors
> > proportional to the number of CPUs in the VM, but there is no standard way
> > to change the number of MSI-X vectors supported by a VF.
> > ...
>
> > +#ifdef CONFIG_PCI_MSI
> > +static ssize_t sriov_vf_msix_count_store(struct device *dev,
> > + struct device_attribute *attr,
> > + const char *buf, size_t count)
> > +{
> > + struct pci_dev *vf_dev = to_pci_dev(dev);
> > + struct pci_dev *pdev = pci_physfn(vf_dev);
> > + int val, ret;
> > +
> > + ret = kstrtoint(buf, 0, &val);
> > + if (ret)
> > + return ret;
> > +
> > + if (val < 0)
> > + return -EINVAL;
> > +
> > + device_lock(&pdev->dev);
> > + if (!pdev->driver || !pdev->driver->sriov_set_msix_vec_count) {
> > + ret = -EOPNOTSUPP;
> > + goto err_pdev;
> > + }
> > +
> > + device_lock(&vf_dev->dev);
> > + if (vf_dev->driver) {
> > + /*
> > + * A driver is already attached to this VF and has configured
> > + * itself based on the current MSI-X vector count. Changing
> > + * the vector size could mess up the driver, so block it.
> > + */
> > + ret = -EBUSY;
> > + goto err_dev;
> > + }
> > +
> > + ret = pdev->driver->sriov_set_msix_vec_count(vf_dev, val);
> > +
> > +err_dev:
> > + device_unlock(&vf_dev->dev);
> > +err_pdev:
> > + device_unlock(&pdev->dev);
> > + return ret ? : count;
> > +}
> > +static DEVICE_ATTR_WO(sriov_vf_msix_count);
> > +
> > +static ssize_t sriov_vf_total_msix_show(struct device *dev,
> > + struct device_attribute *attr,
> > + char *buf)
> > +{
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > + u32 vf_total_msix = 0;
> > +
> > + device_lock(dev);
> > + if (!pdev->driver || !pdev->driver->sriov_get_vf_total_msix)
> > + goto unlock;
> > +
> > + vf_total_msix = pdev->driver->sriov_get_vf_total_msix(pdev);
> > +unlock:
> > + device_unlock(dev);
> > + return sysfs_emit(buf, "%u\n", vf_total_msix);
> > +}
> > +static DEVICE_ATTR_RO(sriov_vf_total_msix);
>
> Can you reverse the order of sriov_vf_total_msix_show() and
> sriov_vf_msix_count_store()? Currently we have:
>
> VF stuff (msix_count_store)
> PF stuff (total_msix)
> more VF stuff related to the above (vf_dev_attrs, are_visible)
>
> so the total_msix bit is mixed in the middle.
No problem, I'll do.
>
> > +#endif
> > +
> > +static struct attribute *sriov_vf_dev_attrs[] = {
> > +#ifdef CONFIG_PCI_MSI
> > + &dev_attr_sriov_vf_msix_count.attr,
> > +#endif
> > + NULL,
> > +};
> > +
> > +static umode_t sriov_vf_attrs_are_visible(struct kobject *kobj,
> > + struct attribute *a, int n)
> > +{
> > + struct device *dev = kobj_to_dev(kobj);
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > +
> > + if (!pdev->is_virtfn)
> > + return 0;
> > +
> > + return a->mode;
> > +}
> > +
> > +const struct attribute_group sriov_vf_dev_attr_group = {
> > + .attrs = sriov_vf_dev_attrs,
> > + .is_visible = sriov_vf_attrs_are_visible,
> > +};
> > +
> > int pci_iov_add_virtfn(struct pci_dev *dev, int id)
> > {
> > int i;
> > @@ -400,18 +487,21 @@ static DEVICE_ATTR_RO(sriov_stride);
> > static DEVICE_ATTR_RO(sriov_vf_device);
> > static DEVICE_ATTR_RW(sriov_drivers_autoprobe);
> >
> > -static struct attribute *sriov_dev_attrs[] = {
> > +static struct attribute *sriov_pf_dev_attrs[] = {
>
> This and the related sriov_pf_attrs_are_visible change below are nice.
> Would you mind splitting them to a preliminary patch, since they
> really aren't related to the concept of *this* patch?
I don't think so, that prepatch will have only two lines of renames
from sriov_dev_attrs to be sriov_pf_dev_attrs. It is not worth the
hassle.
Thanks
>
> > &dev_attr_sriov_totalvfs.attr,
> > &dev_attr_sriov_numvfs.attr,
> > &dev_attr_sriov_offset.attr,
> > &dev_attr_sriov_stride.attr,
> > &dev_attr_sriov_vf_device.attr,
> > &dev_attr_sriov_drivers_autoprobe.attr,
> > +#ifdef CONFIG_PCI_MSI
> > + &dev_attr_sriov_vf_total_msix.attr,
> > +#endif
> > NULL,
> > };
> >
> > -static umode_t sriov_attrs_are_visible(struct kobject *kobj,
> > - struct attribute *a, int n)
> > +static umode_t sriov_pf_attrs_are_visible(struct kobject *kobj,
> > + struct attribute *a, int n)
> > {
> > struct device *dev = kobj_to_dev(kobj);
> >
> > @@ -421,9 +511,9 @@ static umode_t sriov_attrs_are_visible(struct kobject *kobj,
> > return a->mode;
> > }
> >
> > -const struct attribute_group sriov_dev_attr_group = {
> > - .attrs = sriov_dev_attrs,
> > - .is_visible = sriov_attrs_are_visible,
> > +const struct attribute_group sriov_pf_dev_attr_group = {
> > + .attrs = sriov_pf_dev_attrs,
> > + .is_visible = sriov_pf_attrs_are_visible,
> > };
