RE: [Xen-devel] MSI causing softpanics in guest

["Shan, Haitao" <haitao.shan@xxxxxxxxx>]

It is supposed to work on dom0. This is a bug.
Please refer to Keir's reply in this mail thread.

Shan Haitao

-----Original Message-----
From: Anish Bhatt [mailto:anish@xxxxxxxxxxxxx]
Sent: 2008年9月24日 8:08
To: Shan, Haitao
Cc: Jan Beulich; xen-devel@xxxxxxxxxxxxxxxxxxx; Keir Fraser
Subject: Re: [Xen-devel] MSI causing softpanics in guest

No, the bug_on is not triggered in dom0. I also saw the following error
message in xm dmesg, :
/physdev.c:90:d0 remap pirq fa vector 49 while not unmap/
Its part of the code added for MSI, I wonder if its of any significance.

-Anish

Shan, Haitao wrote:
> Just some thoughts on Anish's problem. It seems he reveals a bug in current 
> code, I think.
>
> Currently, evnchn_map_pirq is hooked on msi_map_vector 
> (pci_enable_msi->msi_capability_init->msi_map_vector). Here the pirq type is 
> set to IRQT_PIRQ. Then request_irq should succeed since pirq type is already 
> set.
>
> However, this path only works on the assumption that msi_map_vector and 
> request_irq are executed in the same domain, to be more specific, dom0.
> For PV domU guest, there is no msi_map_vector in its pci_enable_msi ( PV domU 
> actually asks dom0 to do the msi map, instead. This is a decision made by 
> Keir and Yunhong long ago. I think it is base on security considerations). So 
> its irq type is not set correctly (What's more, it incorrectly sets the 
> dom0's irq type). Then request_irq can trigger this bug_on().
>
> Anish, if you use the device in dom0 itself, does it also have this bug_on?
>
> Keir and Jan,
> Do you think this explanation is reasonable for issues Anish met?
>
> Best Regards
> Shan Haitao
>
> -----Original Message-----
> From: Jan Beulich [mailto:jbeulich@xxxxxxxxxx]
> Sent: 2008年9月23日 15:24
> To: Anish Bhatt
> Cc: Keir Fraser; Shan, Haitao; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] MSI causing softpanics in guest
>
> So the question is what irq you pass in to request_irq() and where you got
> it from. Jan
>
>
>>>> Anish Bhatt <anish@xxxxxxxxxx> 23.09.08 07:04 >>>
>>>>
> I put a printk before BUG_ON, Its expecting IRQT_PIRQ, but getting
> IRQT_UNBOUND instead.
> -Anish
>
> Jan Beulich wrote:
>
>>>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 20.09.08 10:15 >>>
>>>>>
>>>>>
>>> On 3.3.0 you need to specify msi=1 on Xen's command line to enable MSI. In
>>> xen-unstable, MSI support is always enabled.
>>>
>>> I changed a check in evtchn_get_xen_pirq() into a BUG_ON() as it looks to me
>>> like it should never trigger. Jan Beulich was the original authour of that
>>> function -- cc'ed in case he can indicate whether I've actually broken the
>>> function. :-)
>>>
>>>
>> No, I think that BUG_ON() you added is valid. It definitely is in the context
>> of startup_pirq(). I'd be curious to know what the type of that irq really 
>> is,
>> but that cannot be determined from the backtrace alone. Anish, could you
>> perhaps add a simple printk() before the BUG_ON()? Unfortunately the
>> driver in question does not appear to be part of the tree, so we can't even
>> check what it does prior to calling request_irq()...
>>
>>  -- Keir
>>
>> On 19/9/08 20:53, "Anish Bhatt" <anish@xxxxxxxxxxxxx> wrote:
>>
>>
>>
>>> lspci shows MSI enabled for PCI device. PCI passthrough works fine.
>>> However, as soon as the MSI driver for card is insmodded, kernel panics.
>>> This is on xen-unstable.  Tried the same with xen-3.3.0 which is
>>> supposed to have MSI passthrough, but the same guest shows MSI as disabled.
>>> Any else seen this bug, or know of a workaround ?
>>>
>>> Trace is as follows :
>>>
>>> ------------[ cut here ]------------
>>> kernel BUG at
>>>
>>>
>>>
>> /usr/src/xen/xen-unstable.hg/linux-2.6.18-xen.hg/drivers/xen/core/evtchn.c:809>
>> !
>>
>>
>>> invalid opcode: 0000 [#1]
>>> SMP
>>> Modules linked in: nfemsg nfdvnet ipv6 binfmt_misc dm_mod nfe usbcore
>>> ext3 jbd processor fuse
>>> CPU:    0
>>> EIP:    0061:[<c02487f5>]    Tainted: GF     VLI
>>> EFLAGS: 00210097   (2.6.18.8-xen #2)
>>> EIP is at evtchn_get_xen_pirq+0x35/0x40
>>> eax: ffffffff   ebx: 00000002   ecx: c0372e60   edx: 00000000
>>> esi: c2103560   edi: c03d3080   ebp: 000004f9   esp: ed385dac
>>> ds: 007b   es: 007b   ss: 0069
>>> Process modprobe (pid: 2590, ti=ed384000 task=ed7b1100 task.ti=ed384000)
>>> Stack: c0248aef 00000000 00000000 00000000 00000000 00000000 00000000
>>> 00000000
>>>        00000000 00000000 00000000 00000000 00000000 00000000 00000000
>>> 00000000
>>>        00000000 00000000 00000000 00000000 00000000 00000000 00000000
>>> 00000000
>>> Call Trace:
>>>  [<c0248aef>] startup_pirq+0x3f/0x250
>>>  [<c0150b50>] setup_irq+0x160/0x1b0
>>>  [<ee0dd270>] nfe_interrupt_handler+0x0/0x30 [nfemsg]
>>>  [<c0150c43>] request_irq+0xa3/0xc0
>>>  [<ee02c8ad>] nfemsg_module_init+0x8ad/0x133e [nfemsg]
>>>  [<c030531b>] cond_resched+0x2b/0x40
>>>  [<c0305369>] wait_for_completion+0x19/0xf0
>>>  [<c0142818>] sys_init_module+0x148/0x1b50
>>>  [<c010595f>] syscall_call+0x7/0xb
>>> Code: 00 00 89 d1 d3 e0 85 05 c4 2c 42 c0 74 1a 8b 14 95 c0 c0 44 c0 89
>>> d0 c1 e8 1c 83 e8 01 75 0c c1 ea 0c 81 e2 ff ff 00 00 89 d0 c3 <0f> 0b
>>> 29 03 a4 f1 32 c0 eb ea 90 83 ec 08 89 74 24 04 89 c6 a1
>>> EIP: [<c02487f5>] evtchn_get_xen_pirq+0x35/0x40 SS:ESP 0069:ed385dac
>>>  ### card [0] start: host progs ###
>>> -bash-3.2#
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: ------------[ cut here ]------------
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: kernel BUG at
>>>
>>>
>>>
>> /usr/src/xen/xen-unstable.hg/linux-2.6.18-xen.hg/drivers/xen/core/evtchn.c:809>
>> !
>>
>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: invalid opcode: 0000 [#1]
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: SMP
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: CPU:    0
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: EIP is at evtchn_get_xen_pirq+0x35/0x40
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: eax: ffffffff   ebx: 00000002   ecx: c0372e60   edx: 00000000
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: esi: c2103560   edi: c03d3080   ebp: 000004f9   esp: ed385dac
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: ds: 007b   es: 007b   ss: 0069
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: Process modprobe (pid: 2590, ti=ed384000 task=ed7b1100
>>> task.ti=ed384000)
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: Stack: c0248aef 00000000 00000000 00000000 00000000 00000000
>>> 00000000 00000000
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel:        00000000 00000000 00000000 00000000 00000000 00000000
>>> 00000000 00000000
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel:        00000000 00000000 00000000 00000000 00000000 00000000
>>> 00000000 00000000
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: Call Trace:
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: Code: 00 00 89 d1 d3 e0 85 05 c4 2c 42 c0 74 1a 8b 14 95 c0 c0
>>> 44 c0 89 d0 c1 e8 1c 83 e8 01 75 0c c1 ea 0c 81 e2 ff ff 00 00 89 d0 c3
>>> <0f> 0b 29 03 a4 f1 32 c0 eb ea 90 83 ec 08 89 74 24 04 89 c6 a1
>>>
>>> Message from syslogd@drake at Sep 19 15:36:44 ...
>>>  kernel: EIP: [<c02487f5>] evtchn_get_xen_pirq+0x35/0x40 SS:ESP
>>> 0069:ed385dac
>>>
>>>
>>
>>
>
>
> --
> As long as the music's loud enough, we won't hear the world falling apart.
>
>
> _______________________________________________
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>


--
As long as the music's loud enough, we won't hear the world falling apart.


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