Re: [Xen-devel] [Query] Assigning PCI ranges to dom0 and domU

[manish jaggi <manishjaggi.oss@xxxxxxxxx>]

On 14 August 2014 15:57, Stefano Stabellini
<stefano.stabellini@xxxxxxxxxxxxx> wrote:
> On Thu, 14 Aug 2014, manish jaggi wrote:
>> On 1 August 2014 19:31, Stefano Stabellini
>> <stefano.stabellini@xxxxxxxxxxxxx> wrote:
>> > On Fri, 1 Aug 2014, manish jaggi wrote:
>> >> Hi Stefano,
>> >>
>> >> I am working on accessing PCI nodes in the doms on ARM (cavium). If there 
>> >> is the below device tree node
>> >> pcie1@0x849000000000 {
>> >>             compatible = "cavium,thunder-pcie";
>> >>         device_type = "pci";
>> >>         msi-parent = <&its>;
>> >>         bus-range = <0 255>;
>> >>         #size-cells = <2>;
>> >>         #address-cells = <3>;
>> >>             reg = <0x8490 0x00000000 0 0x40000000>;  /* Configuration 
>> >> space */
>> >>         ranges = <0x03000000 0x8310 0x00000000 0x8310 0x00000000 0x00 
>> >> 0x10000000>, /* mem ranges */
>> >>             <0x03000000 0x8100 0x00000000 0x8100 0x00000000 0x80 
>> >> 0x00000000>;
>> >>         };
>> >>
>> >>
>> >> How to assign ranges to guest dom0 / domU. Is there a well defined api in 
>> >> xen OR I have to parse the device tree
>> >> ranges and do a 1:1 mapping using map_mmio_regions.
>> >
>> > Firstly you just need to get PCI up and running in Dom0, and you can do
>> > that by passing this device tree node to Dom0 and remapping the
>> > appropriate memory ranges. See for example:
>> >
>> > xen/arch/arm/platforms/xgene-storm.c:xgene_storm_specific_mapping
>> >
>> >
>> > Once that is done, it is time to look at pciback and pcifront and try to
>> > get them running on ARM.
>> >
>> >
>> > I would start by enabling PCI passthrough in the xl toolstack, look at
>> > tools/libxl/libxl_pci.c:libxl__device_pci_add, called by
>> > domcreate_attach_pci. It should be working on ARM following the PV path
>> > (LIBXL_DOMAIN_TYPE_PV).
>> >
>> >
>> > After the toolstack parts are in place, you should be able to see a pci
>> > entry in xenstore (xenstore-ls to list everything that is present in
>> > xenstore). That is the basic information needed by pcifront and pciback
>> > to enstablish a communication channel.
>> I am getting this output, cmd 30 in do_physdev_op is commented though
>>
>> linux:~ # xl pci-assignable-add 01:10.1
>> (XEN) do_physdev_op cmd=30
>> linux:~ # xl pci-assignable-list
>> 0000:01:10.1
>> linux:~ # xenstore-list
>> xenstore-list: Usage: xenstore-list [-h] [-p] [-s] key [...]
>> linux:~ # xenstore-list /local/domain/0
>> name
>> domid
>> linux:~ # xenstore-ls
>> tool = ""
>>  xenstored = ""
>> local = ""
>>  domain = ""
>>   0 = ""
>>    name = "Domain-0"
>>    domid = "0"
>> libxl = ""
>>  pciback = ""
>>   0000-01-10-1 = ""
>>    driver_path = "/sys/bus/pci/drivers/thunder-BGX"
>>
>> Does it look good ?
>>
>> Can you please send a log or point to one, which shows something
>> similar for x86 so that I can use that as a reference.
>
> You should be able to just Google something like that.
> This is what Google gave me as result:
>
>         # xenstore-ls /local/domain/0/backend/pci
>         14 = ""
>          0 = ""
>           domain = "debian-2"
>           frontend = "/local/domain/14/device/pci/0"
>           uuid = "b328cab0-a704-d59f-8133-c5f053f4b639"
>           dev-0 = "0000:00:1d.00"
>           state = "4"
>           online = "1"
>           frontend-id = "14"
>           num_devs = "1"
>           root-0 = "0000:00"
>           root_num = "1"
>         # xenstore-ls /local/domain/14/device/pci
>         0 = ""
>          state = "4"
>          backend-id = "0"
>          backend = "/local/domain/0/backend/pci/14/0"
>          pci-op-ref = "8"
>          event-channel = "27"
>          magic = "7"
>
> You can also simply go through libxl code and see what it is writing to
> xenstore: tools/libxl/libxl_pci.c:libxl__device_pci_add_xenstore.
 Thanks Stefano for a quick response

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