[azure][PATCH v2 2/2] PCI: hv: Use device serial number as PCI domain

Marcelo Henrique Cerri marcelo.cerri at canonical.com
Wed Mar 15 11:39:07 UTC 2017

From: Haiyang Zhang <haiyangz at microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1667527

Use the device serial number as the PCI domain.  The serial numbers start
with 1 and are unique within a VM.  So names, such as VF NIC names, that
include domain number as part of the name, can be shorter than that based
on part of bus UUID previously.  The new names will also stay same for VMs
created with copied VHD and same number of devices.

Signed-off-by: Haiyang Zhang <haiyangz at microsoft.com>
Signed-off-by: Stephen Hemminger <sthemmin at microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Reviewed-by: K. Y. Srinivasan <kys at microsoft.com>
(cherry picked from commit 4a9b0933bdfcd85da840284bf5a0eb17b654b9c2)
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
 drivers/pci/host/pci-hyperv.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index d096237f9591..a679b6acb438 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1320,6 +1320,18 @@ static struct hv_pci_dev *new_pcichild_device(struct hv_pcibus_device *hbus,
 	get_pcichild(hpdev, hv_pcidev_ref_initial);
 	get_pcichild(hpdev, hv_pcidev_ref_childlist);
 	spin_lock_irqsave(&hbus->device_list_lock, flags);
+	/*
+	 * When a device is being added to the bus, we set the PCI domain
+	 * number to be the device serial number, which is non-zero and
+	 * unique on the same VM.  The serial numbers start with 1, and
+	 * increase by 1 for each device.  So device names including this
+	 * can have shorter names than based on the bus instance UUID.
+	 * Only the first device serial number is used for domain, so the
+	 * domain number will not change after the first device is added.
+	 */
+	if (list_empty(&hbus->children))
+		hbus->sysdata.domain = desc->ser;
 	list_add_tail(&hpdev->list_entry, &hbus->children);
 	spin_unlock_irqrestore(&hbus->device_list_lock, flags);
 	return hpdev;

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