Re: [Xen-devel] [PATCH v4 1/4] xen/arm: vgic-v2: Report the correct GICC size to the guest

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 23/10/15 14:28, Ian Campbell wrote:
> On Thu, 2015-10-08 at 19:23 +0100, Julien Grall wrote:
>> The GICv2 DT node is usually used by the guest to know the address/size
>> of the regions (GICD, GICC...) to map into their virtual memory.
>>
>> While the GICv2 spec requires the size of the GICC to be 8KB, we
>> correctly do an 8KB stage-2 mapping but errornously report 256 in the
>> device tree (based on GUEST_GICC_SIZE).
> 
> "erroneously"
> 
>>
>> I bet we didn't see any issue so far because all the registers except
>> GICC_DIR lives in the first 256 bytes of the GICC region and all the guest
> 
> "guests"
> 
>> I have seen so far are driving the GIC with GICC_CTLR.EIOmode =
>> 0.
>>
>> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
> (typo's fixable on commit).

Thank you!

>> ---
>>     This patch is a good candidate to backport for Xen 4.6 - 4.4.
>>     Without it a guest relying on the DT can't use GICC_DIR.
> 
> Noted, but just to check: This patch (and none of the other fixes in this
> series) are all which are required for a guest to be able to use GICC_DIR,
> right?

Correct. BTW, I forgot to mention that this patch may not apply cleanly
on Xen 4.4 as rearranged the guest memory address space in Xen 4.5.

Regards,

-- 
Julien Grall

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