Re: [RFC PATCH v2 00/26] arm64: Dom0 ITS emulation

From: Andre Przywara <andre.przywara@arm.com>
To: Julien Grall <julien.grall@arm.com>,
	Vijay Kilari <vijay.kilari@gmail.com>
Cc: xen-devel <xen-devel@lists.xenproject.org>,
	Jayachandran.Nair@cavium.com,
	Stefano Stabellini <sstabellini@kernel.org>,
	manish.jaggi@cavium.com,
	"prasun.kapoor" <prasun.kapoor@cavium.com>
Subject: Re: [RFC PATCH v2 00/26] arm64: Dom0 ITS emulation
Date: Thu, 19 Jan 2017 14:45:47 +0000	[thread overview]
Message-ID: <d6ee5d26-d116-9dff-0b76-6b748a8821d9@arm.com> (raw)
In-Reply-To: <2b74c3a8-257c-9b09-9ac5-c3f12bc84c30@arm.com>

Hi,

On 19/01/17 14:32, Julien Grall wrote:
> Hi Andre,
> 
> On 19/01/2017 13:50, Andre Przywara wrote:
>> On 19/01/17 12:26, Vijay Kilari wrote:
>>>    I see following issues when running on ThunderX platform with your
>>> patches.
>>> I have debugged and patched/workaround few issues. For issue (5) I
>>> need your  inputs.
>>
>> thanks for the testing and the input. It seems that my anticipation of
>> issues when booting on hardware were right ;-)
>> It seems that some of the issues got fixed already by me rewriting some
>> parts, triggered by comments from Stefano.
>>
>>> 1) Your code base fails to boot xen. Fails at dom0 memory allocation.
>>>     To overcome this I have rebased your patches on top of 4.8 stable
>>> release and this issue is not seen.
>>
>> Can you try to rebase on latest xen master instead and see if that's
>> fixed there by any chance? Because that's where we eventually need to
>> base against anyway. 4.8 stable will not help.
>>
>>> 2)  ITS is not initialized if GICv2 info is not found in GICv3 dt
>>> node. But having GICv2 info is not
>>>    mandatory. So in the below code if GICv2 info is not found ITS is
>>> not initialized.
>>
>> Ah, right, good point. The model is v2 compatible.
>> As this looks like an issue independent from the ITS emulation, can you
>> make a patch? Or does Xen indeed rely on having v2 compat support at the
>> moment? I think you should be able to boot Dom0 with an initrd on
>> ThunderX already, can't you?
> 
> This is a bug in your series and not the current tree. If you look at it
> the if (res) return; will avoid to read the next GICv2 region if the
> first one does not exist.

Ah, right, I misread the code snippet.

> So the problem is where you added the call to the ITS initialization.
> This should be fixed in your series and not separately.

So yes, I will fix it in my next drop.
I guess it should simply read:
    if ( !res )
        dt_device_get_address(node, 1 + gicv3.rdist_count + 2,
...

Thanks for pointing this out.

Cheers,
Andre.

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