Re: [Xen-devel] [PATCH 02/28] ARM: GICv3 ITS: parse and store ITS subnodes from hardware DT

[Andre Przywara <andre.przywara@xxxxxxx>]

Hi,

On 06/02/17 12:58, Julien Grall wrote:
> Hi Andre,
> 
> On 30/01/17 18:31, Andre Przywara wrote:
>> Parse the DT GIC subnodes to find every ITS MSI controller the hardware
>> offers. Store that information in a list to both propagate all of them
>> later to Dom0, but also to be able to iterate over all ITSes.
>> This introduces an ITS Kconfig option.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> ---
>>  xen/arch/arm/Kconfig             |  4 +++
>>  xen/arch/arm/Makefile            |  1 +
>>  xen/arch/arm/gic-v3-its.c        | 71
>> ++++++++++++++++++++++++++++++++++++++++
>>  xen/arch/arm/gic-v3.c            | 12 ++++---
>>  xen/include/asm-arm/gic_v3_its.h | 57 ++++++++++++++++++++++++++++++++
>>  5 files changed, 141 insertions(+), 4 deletions(-)
>>  create mode 100644 xen/arch/arm/gic-v3-its.c
>>  create mode 100644 xen/include/asm-arm/gic_v3_its.h
>>
>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
>> index 2e023d1..bf64c61 100644
>> --- a/xen/arch/arm/Kconfig
>> +++ b/xen/arch/arm/Kconfig
>> @@ -45,6 +45,10 @@ config ACPI
>>  config HAS_GICV3
>>      bool
>>
>> +config HAS_ITS
>> +        bool "GICv3 ITS MSI controller support"
>> +        depends on HAS_GICV3
> 
> Should not this be disabled by default until the last patch of the
> series in order to avoid potential issue if bisecting Xen?

It should work without it, as we only ever map something driven by Dom0,
which does not learn about the virtual until the very last patch.
Actually enabling it early on allows fine-grained build and runtime
testing and bisecting, so we can pinpoint breakages in the VGIC
subsystem to a particular patch.

So do you see any real issues with that? Or was that just a feeling?

Cheers,
Andre.

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