[Hyper-V] SAUCE: pci-hyperv fixes for SR-IOV on Azure

[Joshua R. Poulson]

The following two patches to pci-hyperv were submitted upstream but missed getting pulled into Bjorn's tree. They are needed to fix an issue discovered working on SR-IOV on Azure.

Patch 1: hv_pci_devices_present is called in hv_pci_remove when we remove a PCI device from host (e.g. by disabling SRIOV on a device). In hv_pci_remove, the bus is already removed before the call, so we don't need to rescan the bus in the workqueue scheduled from hv_pci_devices_present. By introducing status hv_pcibus_removed, we can avoid this situation.

Patch 2: A PCI_EJECT message can arrive at the same time we are calling pci_scan_child_bus in the workqueue for the previous PCI_BUS_RELATIONS message or in create_root_hv_pci_bus(), in this case we could potentailly modify the bus from multiple places. Properly lock the bus access.

[Joseph Salisbury (jsalisbury)]

I built a Xenial test kernel with the two patches. The test kernel can be downloaded from:

http://kernel.ubuntu.com/~jsalisbury/lp1665097/xenial/

Can you test this kernel and see if it resolves this bug?

[Dexuan Cui (decui)]

I happened to see this bug and want to add one more patch:
https://git.kernel.org/cgit/linux/kernel/git/helgaas/pci.git/commit/?h=pci/host-hv&id=60e2e2fbafdd1285ae1b4ad39ded41603e0c74d0

[Joseph Salisbury (jsalisbury)]

I included the third patch in the SRU request. I also build a test kernel with all three patches, which can be downloaded from here:

http://kernel.ubuntu.com/~jsalisbury/lp1665097/xenial/

[Joshua R. Poulson (jrp)]

Would it be possible to have a test kernel with these fixes as well as the Mellanox driver update in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1650058 ?

[Joseph Salisbury (jsalisbury)]

@Joshua, sure thing. I'll build it now and post a link shortly.

[Brad Figg (brad-figg)]

This bug is awaiting verification that the kernel in -proposed solves the problem. Please test the kernel and update this bug with the results. If the problem is solved, change the tag 'verification-needed-xenial' to 'verification-done-xenial'. If the problem still exists, change the tag 'verification-needed-xenial' to 'verification-failed-xenial'.

If verification is not done by 5 working days from today, this fix will be dropped from the source code, and this bug will be closed.

See https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to enable and use -proposed. Thank you!

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 4.4.0-65.86

---------------
linux (4.4.0-65.86) xenial; urgency=low

  * linux: 4.4.0-65.86 -proposed tracker (LP: #1667052)

  [ Stefan Bader ]
  * Upgrade Redpine RS9113 driver to support AP mode (LP: #1665211)
    - SAUCE: Redpine driver to support Host AP mode

  * NFS client : permission denied when trying to access subshare, since kernel
    4.4.0-31 (LP: #1649292)
    - fs: Better permission checking for submounts

  * [Hyper-V] SAUCE: pci-hyperv fixes for SR-IOV on Azure (LP: #1665097)
    - SAUCE: PCI: hv: Fix wslot_to_devfn() to fix warnings on device removal
    - SAUCE: pci-hyperv: properly handle pci bus remove
    - SAUCE: pci-hyperv: lock pci bus on device eject

  * [Hyper-V/Azure] Please include Mellanox OFED drivers in Azure kernel and
    image (LP: #1650058)
    - net/mlx4_en: Fix bad WQE issue
    - net/mlx4_core: Fix racy CQ (Completion Queue) free
    - net/mlx4_core: Fix when to save some qp context flags for dynamic VST to VGT
      transitions
    - net/mlx4_core: Avoid command timeouts during VF driver device shutdown

  * Xenial update to v4.4.49 stable release (LP: #1664960)
    - ARC: [arcompact] brown paper bag bug in unaligned access delay slot fixup
    - selinux: fix off-by-one in setprocattr
    - Revert "x86/ioapic: Restore IO-APIC irq_chip retrigger callback"
    - cpumask: use nr_cpumask_bits for parsing functions
    - hns: avoid stack overflow with CONFIG_KASAN
    - ARM: 8643/3: arm/ptrace: Preserve previous registers for short regset write
    - target: Don't BUG_ON during NodeACL dynamic -> explicit conversion
    - target: Use correct SCSI status during EXTENDED_COPY exception
    - target: Fix early transport_generic_handle_tmr abort scenario
    - target: Fix COMPARE_AND_WRITE ref leak for non GOOD status
    - ARM: 8642/1: LPAE: catch pending imprecise abort on unmask
    - mac80211: Fix adding of mesh vendor IEs
    - netvsc: Set maximum GSO size in the right place
    - scsi: zfcp: fix use-after-free by not tracing WKA port open/close on failed
      send
    - scsi: aacraid: Fix INTx/MSI-x issue with older controllers
    - scsi: mpt3sas: disable ASPM for MPI2 controllers
    - xen-netfront: Delete rx_refill_timer in xennet_disconnect_backend()
    - ALSA: seq: Fix race at creating a queue
    - ALSA: seq: Don't handle loop timeout at snd_seq_pool_done()
    - drm/i915: fix use-after-free in page_flip_completed()
    - Linux 4.4.49

  * NFS client : kernel 4.4.0-57 crash with nfsv4 enries in /etc/fstab
    (LP: #1650336)
    - SUNRPC: fix refcounting problems with auth_gss messages.

  * [0bda:0328] Card reader failed after S3 (LP: #1664809)
    - usb: hub: Wait for connection to be reestablished after port reset

  * linux-lts-xenial 4.4.0-63.84~14.04.2 ADT test failure with linux-lts-xenial
    4.4.0-63.84~14.04.2 (LP: #1664912)
    - SAUCE: apparmor: fix link auditing failure due to, uninitialized var

  * ibmvscsis: Add SGL LIMIT (LP: #1662551)
    - ibmvscsis: Add SGL limit

  * [Hyper-V] Bug fixes for storvsc (tagged queuing, error conditions)
    (LP: #1663687)
    - scsi: storvsc: Enable tracking of queue depth
    - scsi: storvsc: Remove the ...