linux-kernel - [PATCH 4.9 082/153] PCI: hv: Fix wslot_to_devfn() to fix warnings on device removal

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Date:   Fri, 10 Mar 2017 10:08:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jake Oshins <jakeo@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [PATCH 4.9 082/153] PCI: hv: Fix wslot_to_devfn() to fix warnings on device removal

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dexuan Cui <decui@...rosoft.com>

commit 60e2e2fbafdd1285ae1b4ad39ded41603e0c74d0 upstream.

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@...rosoft.com>
Signed-off-by: Dexuan Cui <decui@...rosoft.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Haiyang Zhang <haiyangz@...rosoft.com>
CC: K. Y. Srinivasan <kys@...rosoft.com>
CC: Stephen Hemminger <sthemmin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/host/pci-hyperv.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

--- 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;
@@ -483,7 +484,8 @@ 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;
 }
@@ -501,7 +503,7 @@ 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);
 }

 /*