Re: IOMMU groups ... PEX8606 switch?

[Dana Goyette <DanaGoyette@gmail.com>]

On 01/02/2014 01:01 PM, Dana Goyette wrote:
> On 01/02/2014 11:36 AM, Alex Williamson wrote:
>> On Mon, 2013-12-30 at 16:13 -0800, Dana Goyette wrote:
>>> On 12/29/2013 08:16 PM, Alex Williamson wrote:
>>>> On Sat, 2013-12-28 at 23:32 -0800, Dana Goyette wrote:
>>>>> On 12/28/2013 7:23 PM, Alex Williamson wrote:
>>>>>> On Sat, 2013-12-28 at 18:31 -0800, Dana Goyette wrote:
>>>>>>> I have purchased both a SuperMicro X10SAE and an X10SAT, and I
>>>>>>> need to
>>>>>>> soon decide which one to keep.
>>>>>>>
>>>>>>> The SuperMicro X10SAT has all the PCIe x1 slots hidden behind a PLX
>>>>>>> PEX8066 switch, which claims to support ACS.  I'd expect the devices
>>>>>>> downstream of the PLX switch to be in separate groups.
>>>>>>>
>>>>>>> With Linux 3.13-rc5 and "enable overrides for missing ACS
>>>>>>> capabilities"
>>>>>>> applied and set for the Intel root ports, the devices behind the
>>>>>>> switch
>>>>>>> remain stuck in the same group.
>>>>>>>
>>>>>>> In terms of passing devices to different VMs, which is better: all
>>>>>>> devices on different root ports, or all devices behind the one
>>>>>>> ACS-supporting switch?
>>>>>>
>>>>>> Can you provide lspci -vvv info?  If you're getting that for groups
>>>>>> either the switch has ACS capabilities, but doesn't support the
>>>>>> features
>>>>>> we need or we're doing something wrong.  Thanks,
>>>>>>
>>>>> I initially tried attaching the output as a .txt file, but it's too
>>>>> large.  Anyway, here's the output of lspci -nnvvv (you may notice
>>>>> that I
>>>>> moved the Radeon to a different slot).
>>>>
>>>> Well, something seems amiss since the downstream switch ports all seem
>>>> to support and enable the correct set of ACS capabilities.  I'm tending
>>>> to suspect something wrong with the ACS override patch or how it's
>>>> being
>>>> used since your IOMMU group is still based at the root port.  Each root
>>>> port is isolated from the other root ports though, so something is
>>>> happening with the override patch.  Can you provide the kernel command
>>>> line you use to enable ACS overrides and the override patch you're
>>>> using, as it applies to 3.13-rc5?  Thanks,
>>>>
>>>> Alex
>>>>
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>>>>
>>> I'm using the original acs-override patch from this post:
>>> https://lkml.org/lkml/2013/5/30/513
>>>
>>> Kernel parameter is:
>>> pcie_acs_override=id:8086:8c10,id:8086:8c12,id:8086:8c16,id:8086:8c18
>>>
>>> When booting a kernel without the override patch, the following devices
>>> are all in the same group: Intel Root Ports 1, 2, 4, 5; ASMedia SATA
>>> controller; PLX PEX8606 switch; Renesas USB controller; TI Firewire
>>> controller; Intel I210 Ethernet controller.
>>
>> Ok, here's my shot in the dark; we must be detecting something about the
>> upstream switch port to make it fail the ACS test and the only thing I
>> can find that might do this is if the PCI config header on the upstream
>> switch reported itself as a multifunction device.  Multifunction
>> upstream switch ports do need ACS capabilities to make sure that traffic
>> isn't routed back through other functions.  Single function devices do
>> not.  To test that theory, please provide 'lspci -vxs 4:00.0'.  We're
>> looking to see whether the byte at 0xe has the MSB set.  If it does, it
>> lies that it's a multifunction device.  If it doesn't I'll have to get
>> the dart board back out.
>>
>> FWIW, you should be able to work around this by adding id:10b5:8606 to
>> your list of overrides.  Long term, if this is the problem, we'll want
>> to add a quirk to sanitize the multifunction device flag.  Thanks,
>>
>> Alex
>>
>
> 04:00.0 is the ASMedia SATA controller; I'll assume you meant the
> upstream port of the PLX switch.
>
> 05:00.0 PCI bridge: PLX Technology, Inc. PEX 8606 6 Lane, 6 Port PCI
> Express Gen 2 (5.0 GT/s) Switch (rev ba) (prog-if 00 [Normal decode])
>      Flags: bus master, fast devsel, latency 0
>      Memory at eeb00000 (32-bit, non-prefetchable) [size=128K]
>      Bus: primary=05, secondary=06, subordinate=0c, sec-latency=0
>      Memory behind bridge: ee800000-eeafffff
>      Capabilities: [40] Power Management version 3
>      Capabilities: [48] MSI: Enable+ Count=1/4 Maskable+ 64bit+
>      Capabilities: [68] Express Upstream Port, MSI 00
>      Capabilities: [a4] Subsystem: PLX Technology, Inc. PEX 8606 6 Lane,
> 6 Port PCI Express Gen 2 (5.0 GT/s) Switch
>      Capabilities: [100] Device Serial Number ba-86-01-10-b5-df-0e-00
>      Capabilities: [fb4] Advanced Error Reporting
>      Capabilities: [138] Power Budgeting <?>
>      Capabilities: [148] Virtual Channel
>      Capabilities: [448] Vendor Specific Information: ID=0000 Rev=0
> Len=0cc <?>
>      Capabilities: [950] Vendor Specific Information: ID=0001 Rev=0
> Len=010 <?>
>      Kernel driver in use: pcieport
> 00: b5 10 06 86 47 05 10 40 ba 00 04 06 10 00 01 00
> 10: 00 00 b0 ee 00 00 00 00 05 06 0c 00 f1 01 00 00
> 20: 80 ee a0 ee f1 ff 01 00 00 00 00 00 00 00 00 00
> 30: 00 00 00 00 40 00 00 00 00 00 00 00 0a 01 13 00
>
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>

Just in case:

The root port:
00:1c.1 PCI bridge: Intel Corporation 8 Series/C220 Series Chipset 
Family PCI Express Root Port #2 (rev d5) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=00, secondary=05, subordinate=0c, sec-latency=0
	Memory behind bridge: ee800000-eebfffff
	Capabilities: [40] Express Root Port (Slot+), MSI 00
	Capabilities: [80] MSI: Enable- Count=1/1 Maskable- 64bit-
	Capabilities: [90] Subsystem: Super Micro Computer Inc Device 0818
	Capabilities: [a0] Power Management version 3
	Kernel driver in use: pcieport
00: 86 80 12 8c 47 01 10 00 d5 00 04 06 10 00 81 00
10: 00 00 00 00 00 00 00 00 00 05 0c 00 f0 00 00 20
20: 80 ee b0 ee f1 ff 01 00 00 00 00 00 00 00 00 00
30: 00 00 00 00 40 00 00 00 00 00 00 00 0a 02 13 00

The first downstream port:

06:01.0 PCI bridge: PLX Technology, Inc. PEX 8606 6 Lane, 6 Port PCI 
Express Gen 2 (5.0 GT/s) Switch (rev ba) (prog-if 00 [Normal decode])
	Flags: bus master, fast devsel, latency 0
	Bus: primary=06, secondary=07, subordinate=07, sec-latency=0
	Capabilities: [40] Power Management version 3
	Capabilities: [48] MSI: Enable+ Count=1/4 Maskable+ 64bit+
	Capabilities: [68] Express Downstream Port (Slot+), MSI 00
	Capabilities: [a4] Subsystem: PLX Technology, Inc. PEX 8606 6 Lane, 6 
Port PCI Express Gen 2 (5.0 GT/s) Switch
	Capabilities: [100] Device Serial Number ba-86-01-10-b5-df-0e-00
	Capabilities: [fb4] Advanced Error Reporting
	Capabilities: [148] Virtual Channel
	Capabilities: [520] Access Control Services
	Capabilities: [950] Vendor Specific Information: ID=0001 Rev=0 Len=010 <?>
	Kernel driver in use: pcieport
00: b5 10 06 86 47 05 10 00 ba 00 04 06 10 00 01 00
10: 00 00 00 00 00 00 00 00 06 07 07 00 f1 01 00 00
20: f0 ff 00 00 f1 ff 01 00 00 00 00 00 00 00 00 00
30: 00 00 00 00 40 00 00 00 00 00 00 00 0a 01 13 00