Re: [PATCH] updated: arm64: KVM: vgic: deal with GIC sub-page alignment

[Marc Zyngier <marc.zyngier@arm.com>]

On 01/07/16 09:59, Itaru Kitayama wrote:
> Marc,
> That's good news. Can I assume you'd keep the 
> KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET attribute, or would you introduce new
> ones? I ask because either way we need the userland support, be it QEMU 
> or kvmtool. I'm carrying the small QEMU patch at this moment.

You can look at the kvm-arm64/gicv-align branch in my tree, which
contains some of the stuff. At the moment, the attribute is named
KVM_DEV_ARM_VGIC_GRP_GICC_OFFSET, but I don't mind changing the name.

Thanks,

	M.

> 
> 
> On 7/1/16 5:40 PM, Marc Zyngier wrote:
>> Itaru,
>>
>> On 01/07/16 05:57, Itaru Kitayama wrote:
>>> This is merely an update to the patch Marc posted in 2014:
>>>
>>> https://lists.cs.columbia.edu/pipermail/kvmarm/2014-June/010055.html
>>>
>>> This updated patch is against today's current kvmarm git tree tag,
>>> kvm-for-arm-v4.7-rc6.
>>>
>>> The GIC CPU interface is always 4k aligned. If the host is using
>>> 64k pages, it is critical to place the guest's GICC interface at the
>>> same relative alignment as the host's GICV. Failure to do so results
>>> in an impossibility for the guest to deal with interrupts.
>>>
>>> Add a KVM_DEV_ARM_VGIC_GRP_ADDR_OFFSET attribute for the VGIC, allowing
>>> userspace to retrieve the GICV offset in a page. It becomes then trivial
>>> to adjust the GICC base address for the guest.
>>>
>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com <https://lists.cs.columbia.edu/mailman/listinfo/kvmarm>>
>>> Signed-off-by: Itaru Kitayama <itaru.kitayama@riken.jp>
>>
>> I'm working on a much more complete patch series that deals with this
>> and a bit more. Hopefully for the 4.9 time frame.
>>
>> Thanks,
>>
>> 	M.
>>
> 


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