Re: [Xen-devel] xl pci-attach silently fails the first time

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Mon, Dec 01, 2014 at 12:01:51PM -0500, Konrad Rzeszutek Wilk wrote:
> On Mon, Dec 01, 2014 at 02:32:44PM +0100, Olaf Hering wrote:
> > On Mon, Dec 01, Olaf Hering wrote:
> > 
> > > # xl pci-assignable-add 01:10.0
> > > # xl pci-assignable-list
> > > 0000:01:10.0
> > > # xl create -f domU.cfg
> > > # xl console domU
> > > ## lspci gives just emulated PCI devices
> > 
> > ttyS0:Rescue:~ # lspci 
> > 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
> > 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
> > 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton 
> > II]
> > 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
> > 00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 
> > 01)
> > 00:03.0 VGA compatible controller: Cirrus Logic GD 5446
> > 00:04.0 Ethernet controller: Realtek Semiconductor Co., Ltd. 
> > RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev ff)
> > 
> > > ## detach from domU console
> > > # xl pci-attach domU 0000:01:10.0
> > > # xl pci-list domU
> > > Vdev Device
> > > 04.0 0000:01:10.0
> > > 
> > > # xl console domU
> > > ## lspci gives just emulated PCI devices
> > 
> > ttyS0:Rescue:~ # lspci 
> > 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
> > 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
> > 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton 
> > II]
> > 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
> > 00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 
> > 01)
> > 00:03.0 VGA compatible controller: Cirrus Logic GD 5446
> > 00:04.0 Ethernet controller: Realtek Semiconductor Co., Ltd. 
> > RTL-8100/8101L/8139 PCI Fast Ethernet Adapter (rev 01)
> > 
> > > ## detach from domU console
> > > # xl pci-detach domU 0000:01:10.0
> > Now lspci shows that the emulated network card is gone.
> 
> > ttyS0:Rescue:~ # lspci 
> > 00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
> > 00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
> > 00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton 
> > II]
> > 00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
> > 00:02.0 Unassigned class [ff80]: XenSource, Inc. Xen Platform Device (rev 
> > 01)
> > 00:03.0 VGA compatible controller: Cirrus Logic GD 5446
> > 
> > > # xl pci-attach domU 0000:01:10.0
> > > # xl pci-list domU
> > > Vdev Device
> > > 04.0 0000:01:10.0
> > > # xl console domU
> > > ## lspci shows now also the assigned host device
> > 
> > 
> > So the actual bug is that the very first time after pci-attach the guests
> > "00:04.0" PCI device is (most likely) replaced with the host PCI device. 
> > Just
> > the guest does not notice that "00:04.0" was actually already gone after 
> > unplug.
> 
> That is odd - I see any device 'hot-plugged' being added at 00:05 and further.

I have to apologize. The reason it works for me is because the emulated
device gets unplugged quite early:

# lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 03)
00:02.0 Class ff80: XenSource, Inc. Xen Platform Device (rev 01)
00:03.0 VGA compatible controller: Cirrus Logic GD 5446

[and here I run 'xl pci-attach USB 00:1a.0]

# [   30.609802] hpet1: lost 1589 rtc interrupts
[   30.672030] hpet1: lost 2200 rtc interrupts
[   30.672030] hpet1: lost 2201 rtc interrupts
[   30.672030] hpet1: lost 2200 rtc interrupts
[   30.899341] pci 0000:00:04.0: [8086:1c2d] type 00 class 0x0c0320

And the other test I have been running is when the guest is booted
with an PCI device (and then unplugged):

# lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 01)
00:02.0 VGA compatible controller: Cirrus Logic GD 5446
00:03.0 Class ff80: XenSource, Inc. Xen Platform Device (rev 01)
00:05.0 USB Controller: Intel Corporation Cougar Point USB Enhanced Host 
Controller #2 (rev 04)

But oddly enough when I do 'pci-detach' and then 'pci-attach' I get:
lspci
00:00.0 Host bridge: Intel Corporation 440FX - 82441FX PMC [Natoma] (rev 02)
00:01.0 ISA bridge: Intel Corporation 82371SB PIIX3 ISA [Natoma/Triton II]
00:01.1 IDE interface: Intel Corporation 82371SB PIIX3 IDE [Natoma/Triton II]
00:01.3 Bridge: Intel Corporation 82371AB/EB/MB PIIX4 ACPI (rev 01)
00:02.0 VGA compatible controller: Cirrus Logic GD 5446
00:03.0 Class ff80: XenSource, Inc. Xen Platform Device (rev 01)
00:04.0 USB Controller: Intel Corporation Cougar Point USB Enhanced Host 
Controller #2 (rev 04)

so something is busted as you surmised

And it looks to be busted in two cases - I see the 'hpet1' issues
and the guest then crashes!
> 
> > 
> > I wonder why the unplug code in xen_platform.c does just a qdev_free() 
> > instead
> > of a real pci-detach kind of thing. I'm sure this could be done at least for
> > emulated network cards.
> > 
> > Olaf
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxx
> > http://lists.xen.org/xen-devel
> 
> _______________________________________________
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> Xen-devel@xxxxxxxxxxxxx
> http://lists.xen.org/xen-devel

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