On Tue, Jun 12, 2018 at 09:40:37AM -0700, Stephen Hemminger wrote:
> The Hyper-V host API for PCI provides a unique "serial number" which
> can be used as the basis for sysfs PCI slot table. This can be useful
> for cases where userspace wants to find the PCI device based on
> serial number.
>
> When an SR-IOV NIC is added, the host sends an attach message
> with a serial number. The kernel doesn't use the serial number, but
> it is useful when doing the same thing in a userspace driver such
> as the DPDK. By having /sys/bus/pci/slots/N it provides a direct
> way to find the matching PCI device.
>
> There may be some cases where the serial number is not unique such
> as when using GPU's. But the PCI slot infrastructure will handle
> that.
>
> This also shortens the network device names generated by
> systemd/udev. The new names use slot (ens2) rather than
> PCI address (enP2p0s2).
Hi Stephen,
I wanted to apply this patch but wanted to make sure all HV
maintainers are in agreement first since this looks like
a significant user-space ABI change.
I would also ask Bjorn's opinion on this since he has more
insights into the slot interface history.
Thanks,
Lorenzo
> Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
> ---
> v2
> - retarget for current filenames in PCI next
> - remove debug log message
>
> drivers/pci/controller/pci-hyperv.c | 30 +++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
>
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 6cc5036ac83c..4e3575716ced 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -88,6 +88,8 @@ static enum pci_protocol_version_t pci_protocol_version;
>
> #define STATUS_REVISION_MISMATCH 0xC0000059
>
> +#define SLOT_NAME_SIZE 21
> +
> /*
> * Message Types
> */
> @@ -493,6 +495,7 @@ struct hv_pci_dev {
> struct list_head list_entry;
> refcount_t refs;
> enum hv_pcichild_state state;
> + struct pci_slot *pci_slot;
> struct pci_function_description desc;
> bool reported_missing;
> struct hv_pcibus_device *hbus;
> @@ -1454,6 +1457,28 @@ static void prepopulate_bars(struct hv_pcibus_device *hbus)
> spin_unlock_irqrestore(&hbus->device_list_lock, flags);
> }
>
> +static void hv_pci_assign_slots(struct hv_pcibus_device *hbus)
> +{
> + struct hv_pci_dev *hpdev;
> + char name[SLOT_NAME_SIZE];
> + unsigned long flags;
> + int slot_nr;
> +
> + spin_lock_irqsave(&hbus->device_list_lock, flags);
> + list_for_each_entry(hpdev, &hbus->children, list_entry) {
> + if (hpdev->pci_slot)
> + continue;
> +
> + slot_nr = PCI_SLOT(wslot_to_devfn(hpdev->desc.win_slot.slot));
> + snprintf(name, SLOT_NAME_SIZE, "%u", hpdev->desc.ser);
> + hpdev->pci_slot = pci_create_slot(hbus->pci_bus, slot_nr,
> + name, NULL);
> + if (!hpdev->pci_slot)
> + pr_warn("pci_create slot %s failed\n", name);
> + }
> + spin_unlock_irqrestore(&hbus->device_list_lock, flags);
> +}
> +
> /**
> * create_root_hv_pci_bus() - Expose a new root PCI bus
> * @hbus: Root PCI bus, as understood by this driver
> @@ -1477,6 +1502,7 @@ static int create_root_hv_pci_bus(struct hv_pcibus_device *hbus)
> pci_lock_rescan_remove();
> pci_scan_child_bus(hbus->pci_bus);
> pci_bus_assign_resources(hbus->pci_bus);
> + hv_pci_assign_slots(hbus);
> pci_bus_add_devices(hbus->pci_bus);
> pci_unlock_rescan_remove();
> hbus->state = hv_pcibus_installed;
> @@ -1739,6 +1765,7 @@ static void pci_devices_present_work(struct work_struct *work)
> */
> pci_lock_rescan_remove();
> pci_scan_child_bus(hbus->pci_bus);
> + hv_pci_assign_slots(hbus);
> pci_unlock_rescan_remove();
> break;
>
> @@ -1855,6 +1882,9 @@ static void hv_eject_device_work(struct work_struct *work)
> list_del(&hpdev->list_entry);
> spin_unlock_irqrestore(&hpdev->hbus->device_list_lock, flags);
>
> + if (hpdev->pci_slot)
> + pci_destroy_slot(hpdev->pci_slot);
> +
> memset(&ctxt, 0, sizeof(ctxt));
> ejct_pkt = (struct pci_eject_response *)&ctxt.pkt.message;
> ejct_pkt->message_type.type = PCI_EJECTION_COMPLETE;
> --
> 2.17.1
>
