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  1. 22 May, 2019 37 commits
  3. 16 May, 2019 3 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.19.44 · dafc674b
      Greg Kroah-Hartman authored
      dafc674b
    • Dexuan Cui's avatar
      PCI: hv: Add pci_destroy_slot() in pci_devices_present_work(), if necessary · 9fa23ea1
      Dexuan Cui authored 
      commit 340d4556 upstream.

When we hot-remove a device, usually the host sends us a PCI_EJECT message,
and a PCI_BUS_RELATIONS message with bus_rel->device_count == 0.

When we execute the quick hot-add/hot-remove test, the host may not send
us the PCI_EJECT message if the guest has not fully finished the
initialization by sending the PCI_RESOURCES_ASSIGNED* message to the
host, so it's potentially unsafe to only depend on the
pci_destroy_slot() in hv_eject_device_work() because the code path

create_root_hv_pci_bus()
 -> hv_pci_assign_slots()

is not called in this case. Note: in this case, the host still sends the
guest a PCI_BUS_RELATIONS message with bus_rel->device_count == 0.

In the quick hot-add/hot-remove test, we can have such a race before
the code path

pci_devices_present_work()
 -> new_pcichild_device()

adds the new device into the hbus->children list, we may have already
received the PCI_EJECT message, and since the tasklet handler

hv_pci_onchannelcallback()

may fail to find the "hpdev" by calling

get_pcichild_wslot(hbus, dev_message->wslot.slot)

hv_pci_eject_device() is not called; Later, by continuing execution

create_root_hv_pci_bus()
 -> hv_pci_assign_slots()

creates the slot and the PCI_BUS_RELATIONS message with
bus_rel->device_count == 0 removes the device from hbus->children, and
we end up being unable to remove the slot in

hv_pci_remove()
 -> hv_pci_remove_slots()

Remove the slot in pci_devices_present_work() when the device
is removed to address this race.

pci_devices_present_work() and hv_eject_device_work() run in the
singled-threaded hbus->wq, so there is not a double-remove issue for the
slot.

We cannot offload hv_pci_eject_device() from hv_pci_onchannelcallback()
to the workqueue, because we need the hv_pci_onchannelcallback()
synchronously call hv_pci_eject_device() to poll the channel
ringbuffer to work around the "hangs in hv_compose_msi_msg()" issue
fixed in commit de0aa7b2 ("PCI: hv: Fix 2 hang issues in
hv_compose_msi_msg()")

Fixes: a15f2c08 ("PCI: hv: support reporting serial number as slot information")
Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
[lorenzo.pieralisi@arm.com: rewritten commit log]
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarStephen Hemminger <stephen@networkplumber.org>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      9fa23ea1
    • Dexuan Cui's avatar
      PCI: hv: Add hv_pci_remove_slots() when we unload the driver · 76888d13
      Dexuan Cui authored 
      commit 15becc2b upstream.

When we unload the pci-hyperv host controller driver, the host does not
send us a PCI_EJECT message.

In this case we also need to make sure the sysfs PCI slot directory is
removed, otherwise a command on a slot file eg:

"cat /sys/bus/pci/slots/2/address"

will trigger a

"BUG: unable to handle kernel paging request"

and, if we unload/reload the driver several times we would end up with
stale slot entries in PCI slot directories in /sys/bus/pci/slots/

root@localhost:~# ls -rtl  /sys/bus/pci/slots/
total 0
drwxr-xr-x 2 root root 0 Feb  7 10:49 2
drwxr-xr-x 2 root root 0 Feb  7 10:49 2-1
drwxr-xr-x 2 root root 0 Feb  7 10:51 2-2

Add the missing code to remove the PCI slot and fix the current
behaviour.

Fixes: a15f2c08 ("PCI: hv: support reporting serial number as slot information")
Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
[lorenzo.pieralisi@arm.com: reformatted the log]
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: default avatarStephen Hemminger <sthemmin@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      76888d13
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