Re: [Xen-devel] [PATCH v5 00/16] Xen ARM DomU ACPI support

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

On 2016/9/14 15:14, Julien Grall wrote:
> Hello,
> 
> On 14/09/2016 02:06, Stefano Stabellini wrote:
>> On Wed, 14 Sep 2016, Shannon Zhao wrote:
>>> On 2016/9/13 23:17, Julien Grall wrote:
>>>>
>>>>
>>>> On 13/09/16 14:06, Shannon Zhao wrote:
>>>>> Hi Julien,
>>>>
>>>> Hello Shannon,
>>>>
>>>>> On 2016/9/13 19:56, Julien Grall wrote:
>>>>>> Hi Shannon,
>>>>>>
>>>>>> On 02/09/16 03:55, Shannon Zhao wrote:
>>>>>>> From: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>>>>>>>
>>>>>>> The design of this feature is described as below.
>>>>>>> Firstly, the toolstack (libxl) generates the ACPI tables
>>>>>>> according the
>>>>>>> number of vcpus and gic controller.
>>>>>>>
>>>>>>> Then, it copies these ACPI tables to DomU non-RAM memory map
>>>>>>> space and
>>>>>>> passes them to UEFI firmware through the "ARM multiboot" protocol.
>>>>>>>
>>>>>>> At last, UEFI gets the ACPI tables through the "ARM multiboot"
>>>>>>> protocol
>>>>>>> and installs these tables like the usual way and passes both ACPI
>>>>>>> and DT
>>>>>>> information to the Xen DomU.
>>>>>>>
>>>>>>> Currently libxl only generates RSDP, XSDT, GTDT, MADT, FADT, DSDT
>>>>>>> tables
>>>>>>> since it's enough now.
>>>>>>>
>>>>>>> This has been tested using guest kernel with the Dom0 ACPI support
>>>>>>> patches which could be fetched from linux master or:
>>>>>>> https://git.kernel.org/cgit/linux/kernel/git/mfleming/efi.git/log/?h=efi/arm-xen
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> The UEFI binary could be fetched from or built from edk2 master
>>>>>>> branch:
>>>>>>> http://people.linaro.org/~shannon.zhao/DomU_ACPI/XEN_EFI.fd
>>>>>>
>>>>>> On which commit this EFI binary is based? I am trying to rebuild
>>>>>> myself,
>>>>>> and go no luck to boot it so far.
>>>>>>
>>>>> I forgot the exact commit. But I just tried below commit which adds
>>>>> the
>>>>> support to edk2 and the guest can boot up successfully with ACPI.
>>>>>
>>>>> 402dde6 ArmVirtPkg/ArmVirtXen: Add ACPI support for Virt Xen ARM
>>>>
>>>> Thanks, the commit does not build on my platform. After some help for
>>>> Ard I managed to boot UEFI with the patch [1] applied.
>>>>
>>>> However Linux does not boot when passing acpi=on and abort with the
>>>> following message:
>>>>
>>>> (d86) 6RCU: Adjusting geometry for rcu_fanout_leaf=64, nr_cpu_ids=1
>>>> (d86) 6NR_IRQS:64 nr_irqs:64 0
>>>> (d86) 3No valid GICC entries exist
>>>> (d86) 0Kernel panic - not syncing: No interrupt controller found.
>>>> (d86) dCPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-rc6+ #420
>>>> (d86) dHardware name: XENVM-4.8 (DT)
>>>> (d86) Call trace:
>>>> (d86) [<ffff000008088708>] dump_backtrace+0x0/0x1a8
>>>> (d86) [<ffff0000080888c4>] show_stack+0x14/0x20
>>>> (d86) [<ffff0000083d6c2c>] dump_stack+0x94/0xb8
>>>> (d86) [<ffff00000815c24c>] panic+0x10c/0x250
>>>> (d86) [<ffff000008c223f8>] init_IRQ+0x24/0x2c
>>>> (d86) [<ffff000008c20a24>] start_kernel+0x238/0x394
>>>> (d86) [<ffff000008c201bc>] __primary_switched+0x30/0x74
>>>> (d86) 0---[ end Kernel panic - not syncing: No interrupt controller
>>>> found.
>>>>
>>>> This is because the header.length for GICC is not valid for ACPI 5.1
>>>> (see BAD_MADT_GICC_ENTRY). So please check all the size of each table
>>>> against ACPI 5.1.
>>>>
>>> Oops. The reason is that acpi_madt_generic_interrupt in Xen is already
>>> updated to ACPI 6.0 and the length is 80 not 76 of ACPI 5.1.
>>> One solution is that we still use ACPI 5.1 and make gicc->header.length
>>> 76. Other one is that we update to ACPI 6.0 since the Xen ARM ACPI
>>> support in Linux was introduced after ACPI 6.0.
>>>
>>> Which one do you prefer?
>>
>> Certainly the versions of all tables need to be consistent. I would
>> prefer to have ACPI 6.0 but 5.1 is acceptable too (especially if
>> upgrading to 6.0 causes a large amount of changes to your patches).
> 
> I disagree on this, we should use the first version of ACPI that is
> fully supporting ARM because a guest operating system may choose to
> support the first one (there is a lot hardware platform out which only
> provides ACPI 5.1).
> 
So you prefer we should set the gicc->header.length to 76 and still use
ACPI 5.1, right?

Thanks,
-- 
Shannon


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