Possible subject, since this adds *two* files, not just "a file":
PCI/IOV: Add sysfs MSI-X vector assignment interface
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.
> +#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?
> &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,
> };
