[PATCH] PCI: hv: fix wslot_to_devfn()

[Bjorn Helgaas]

On Tue, Feb 07, 2017 at 09:00:10AM +0000, Dexuan Cui wrote:
> 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>
> Cc: stable at vger.kernel.org
> Cc: K. Y. Srinivasan <kys at microsoft.com>
> CC: Haiyang Zhang <haiyangz at microsoft.com>
> Cc: Stephen Hemminger <sthemmin at microsoft.com>

Applied with Haiyang's ack to pci/host-hv for v4.11, thanks!

> ---
>  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
>