From 4e0f0591c11c4669ceb0168a19a061b2fb607052 Mon Sep 17 00:00:00 2001 From: Haiyang Zhang Date: Thu, 15 Aug 2019 17:01:45 +0000 Subject: [PATCH] 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 --- drivers/pci/controller/pci-hyperv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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) { -- 2.39.5