Public bug reported:

The following patch fixes a problem with "[PATCH] pci-hyperv: Use device
serial number as PCI domain" where some drivers were expecting a u16
instead of a u32 for PCI device serial numbers, as observed by Oops and
hangs in Azure on NC and NV GPU instances.

From: Haiyang Zhang <haiya...@microsoft.com>

This patch uses the lower 16 bits of the serial number as PCI
domain, otherwise some drivers may not be able to handle it.

Signed-off-by: Haiyang Zhang <haiya...@microsoft.com>
---
 drivers/pci/host/pci-hyperv.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index e73880c..b18dff3 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -1334,9 +1334,11 @@ static void put_pcichild(struct hv_pci_dev *hpdev,
         * 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.
+        * The lower 16 bits of the serial number is used, otherwise some
+        * drivers may not be able to handle it.
         */
        if (list_empty(&hbus->children))
-               hbus->sysdata.domain = desc->ser;
+               hbus->sysdata.domain = desc->ser & 0xFFFF;
        list_add_tail(&hpdev->list_entry, &hbus->children);
        spin_unlock_irqrestore(&hbus->device_list_lock, flags);
        return hpdev;
-- 
1.7.1

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Confirmed

** Patch added: "0001-pci-hyperv-use-only-16-bit-integer-for-pci-domain.patch"
   
https://bugs.launchpad.net/bugs/1684971/+attachment/4865622/+files/0001-pci-hyperv-use-only-16-bit-integer-for-pci-domain.patch

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https://bugs.launchpad.net/bugs/1684971

Title:
  [Hyper-V][SAUCE] pci-hyperv: Use only 16 bit integer for PCI domain

Status in linux package in Ubuntu:
  Confirmed

Bug description:
  The following patch fixes a problem with "[PATCH] pci-hyperv: Use
  device serial number as PCI domain" where some drivers were expecting
  a u16 instead of a u32 for PCI device serial numbers, as observed by
  Oops and hangs in Azure on NC and NV GPU instances.

  From: Haiyang Zhang <haiya...@microsoft.com>

  This patch uses the lower 16 bits of the serial number as PCI
  domain, otherwise some drivers may not be able to handle it.

  Signed-off-by: Haiyang Zhang <haiya...@microsoft.com>
  ---
   drivers/pci/host/pci-hyperv.c |    4 +++-
   1 files changed, 3 insertions(+), 1 deletions(-)

  diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
  index e73880c..b18dff3 100644
  --- a/drivers/pci/host/pci-hyperv.c
  +++ b/drivers/pci/host/pci-hyperv.c
  @@ -1334,9 +1334,11 @@ static void put_pcichild(struct hv_pci_dev *hpdev,
         * 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.
  +      * The lower 16 bits of the serial number is used, otherwise some
  +      * drivers may not be able to handle it.
         */
        if (list_empty(&hbus->children))
  -             hbus->sysdata.domain = desc->ser;
  +             hbus->sysdata.domain = desc->ser & 0xFFFF;
        list_add_tail(&hpdev->list_entry, &hbus->children);
        spin_unlock_irqrestore(&hbus->device_list_lock, flags);
        return hpdev;
  -- 
  1.7.1

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