From: Haiyang Zhang Date: Thu, 15 Aug 2019 17:01:45 +0000 (+0000) Subject: PCI: hv: Use bytes 4 and 5 from instance ID as the PCI domain numbers X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f73f8a504e27959576a2f4d85182202561e426f2;p=linux.git PCI: hv: Use bytes 4 and 5 from instance ID as the PCI domain numbers As recommended by Azure host team, the bytes 4, 5 have more uniqueness (info entropy) than bytes 8, 9 so use them as the PCI domain numbers. On older hosts, bytes 4, 5 can also be used -- no backward compatibility issues are introduced and the chance of collision is greatly reduced. In the rare cases of collision, the driver code detects and finds another number that is not in use. Suggested-by: Michael Kelley Signed-off-by: Haiyang Zhang Signed-off-by: Lorenzo Pieralisi Acked-by: Sasha Levin --- diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index 4caa3388692ab..3a56de6b2ec2c 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -2590,7 +2590,7 @@ static int hv_pci_probe(struct hv_device *hdev, * (2) There will be no overlap between domains (after fixing possible * collisions) in the same VM. */ - dom_req = hdev->dev_instance.b[8] << 8 | hdev->dev_instance.b[9]; + dom_req = hdev->dev_instance.b[5] << 8 | hdev->dev_instance.b[4]; dom = hv_get_dom_num(dom_req); if (dom == HVPCI_DOM_INVALID) {