linux-kernel - [PATCH] PCI: hv: fix wslot_to

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Message-ID: <MWHPR03MB26692E8BCBD2B7129EFE1445BF430@MWHPR03MB2669.namprd03.prod.outlook.com>
Date:   Tue, 7 Feb 2017 09:00:10 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        Jake Oshins <jakeo@...rosoft.com>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "apw@...onical.com" <apw@...onical.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Subject: [PATCH] PCI: hv: fix wslot_to_devfn()

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>
Cc: stable@...r.kernel.org
Cc: K. Y. Srinivasan <kys@...rosoft.com>
CC: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
---
 drivers/pci/host/pci-hyperv.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

The patch is co-made by Jake and me.

diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
index 3efcc7b..cd114c6 100644
--- a/drivers/pci/host/pci-hyperv.c
+++ b/drivers/pci/host/pci-hyperv.c
@@ -130,7 +130,8 @@ enum pci_message_type {
  */
 union win_slot_encoding {
 	struct {
-		u32	func:8;
+		u32	dev:5;
+		u32	func:3;
 		u32	reserved:24;
 	} bits;
 	u32 slot;
@@ -485,7 +486,8 @@ 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;
 }
@@ -503,7 +505,7 @@ 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);
 }
 
 /*
-- 
1.8.3.1