[SRU][Xenial][PATCH 1/3] UBUNTU: SAUCE: PCI: hv: Fix wslot_to_devfn() to fix warnings on device removal

[Joseph Salisbury]

From: Dexuan Cui <decui at microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1665097

The devfn of 00:02.0 is 0x10.  devfn_to_wslot(0x10) == 0x2, and
wslot_to_devfn(0x2) should be 0x10, while it's 0x2 in the current code.

Due to this, hv_eject_device_work() -> pci_get_domain_bus_and_slot()
returns NULL and pci_stop_and_remove_bus_device() is not called.

Later when the real device driver's .remove() is invoked by
hv_pci_remove() -> pci_stop_root_bus(), some warnings can be noticed
because the VM has lost the access to the underlying device at that
time.

Signed-off-by: Jake Oshins <jakeo at microsoft.com>
Signed-off-by: Dexuan Cui <decui at microsoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Acked-by: Haiyang Zhang <haiyangz at microsoft.com>
CC: stable at vger.kernel.org
CC: K. Y. Srinivasan <kys at microsoft.com>
CC: Stephen Hemminger <sthemmin at microsoft.com>
Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
---
 drivers/pci/host/pci-hyperv.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 6955ffdb..b0ee99c6 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -130,7 +130,8 @@ union pci_version {
  */
 union win_slot_encoding {
 	struct {
-		u32	func:8;
+		u32	dev:5;
+		u32	func:3;
 		u32	reserved:24;
 	} bits;
 	u32 slot;
@@ -482,7 +483,8 @@ static u32 devfn_to_wslot(int devfn)
 	union win_slot_encoding wslot;
 
 	wslot.slot = 0;
-	wslot.bits.func = PCI_SLOT(devfn) | (PCI_FUNC(devfn) << 5);
+	wslot.bits.dev = PCI_SLOT(devfn);
+	wslot.bits.func = PCI_FUNC(devfn);
 
 	return wslot.slot;
 }
@@ -500,7 +502,7 @@ static int wslot_to_devfn(u32 wslot)
 	union win_slot_encoding slot_no;
 
 	slot_no.slot = wslot;
-	return PCI_DEVFN(0, slot_no.bits.func);
+	return PCI_DEVFN(slot_no.bits.dev, slot_no.bits.func);
 }
 
 /*
-- 
2.7.4