| Message ID | d37c2b36-a372-68ea-3598-4acf2aad58a1@gmail.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series | PCI: Expose ari_enabled in sysfs | expand |
On Fri, Jan 05, 2018 at 12:51:55PM -0600, Stuart Hayes wrote: > Some multifunction PCI devices with more than 8 functions use "alternative > routing-ID interpretation" (ARI), which means the 8-bit device/function > number field will be interpreted as 8 bits specifying the function number > (the device number is 0 implicitly), rather than the upper 5 bits > specifying the device number and the lower 3 bits specifying the function > number. The kernel can enable and use this. > > Expose in a sysfs attribute whether the kernel has enabled ARI, so that a > program in userspace won't have to parse PCI devices and PCI configuration > space to figure out if it is enabled. This will allow better predictable > network naming using PCI function numbers without using PCI bus or device > numbers, which is desirable because bus and device numbers can change with > system configuration but function numbers will not. > > Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com> Applied to pci/virtualization for v4.16, thanks! > --- > > --- linux-4.15-rc6/drivers/pci/pci-sysfs.c.orig 2017-12-31 17:47:43.000000000 -0500 > +++ linux-4.15-rc6/drivers/pci/pci-sysfs.c 2018-01-02 13:58:23.372928377 -0500 > @@ -278,6 +278,16 @@ static ssize_t subordinate_bus_number_sh > } > static DEVICE_ATTR_RO(subordinate_bus_number); > > +static ssize_t ari_enabled_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct pci_dev *pci_dev = to_pci_dev(dev); > + > + return sprintf(buf, "%u\n", pci_ari_enabled(pci_dev->bus)); > +} > +static DEVICE_ATTR_RO(ari_enabled); > + > static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, > char *buf) > { > @@ -786,6 +796,7 @@ static struct attribute *pci_dev_attrs[] > &dev_attr_devspec.attr, > #endif > &dev_attr_driver_override.attr, > + &dev_attr_ari_enabled.attr, > NULL, > }; >
--- linux-4.15-rc6/drivers/pci/pci-sysfs.c.orig 2017-12-31 17:47:43.000000000 -0500 +++ linux-4.15-rc6/drivers/pci/pci-sysfs.c 2018-01-02 13:58:23.372928377 -0500 @@ -278,6 +278,16 @@ static ssize_t subordinate_bus_number_sh } static DEVICE_ATTR_RO(subordinate_bus_number); +static ssize_t ari_enabled_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct pci_dev *pci_dev = to_pci_dev(dev); + + return sprintf(buf, "%u\n", pci_ari_enabled(pci_dev->bus)); +} +static DEVICE_ATTR_RO(ari_enabled); + static ssize_t modalias_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -786,6 +796,7 @@ static struct attribute *pci_dev_attrs[] &dev_attr_devspec.attr, #endif &dev_attr_driver_override.attr, + &dev_attr_ari_enabled.attr, NULL, };
Some multifunction PCI devices with more than 8 functions use "alternative routing-ID interpretation" (ARI), which means the 8-bit device/function number field will be interpreted as 8 bits specifying the function number (the device number is 0 implicitly), rather than the upper 5 bits specifying the device number and the lower 3 bits specifying the function number. The kernel can enable and use this. Expose in a sysfs attribute whether the kernel has enabled ARI, so that a program in userspace won't have to parse PCI devices and PCI configuration space to figure out if it is enabled. This will allow better predictable network naming using PCI function numbers without using PCI bus or device numbers, which is desirable because bus and device numbers can change with system configuration but function numbers will not. Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com> ---