Re: [PATCH] xen/arm: Save/restore GICH_VMCR on domain context switch

[George Dunlap <george.dunlap@eu.citrix.com>]

On 02/18/2014 02:51 PM, Ian Campbell wrote:
> On Tue, 2014-02-18 at 13:58 +0000, Julien Grall wrote:
>> GICH_VMCR register contains alias to important bits of GICV interface such as:
>>      - priority mask of the CPU
>>      - EOImode
>>      - ...
>>
>> We were safe because Linux guest always use the same value for this bits.
>> When new guests will handle priority or change EOI mode, VCPU interrupt
>> management will be in a wrong state.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> Cc: George Dunlap <george.dunlap@citrix.com>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>
>
>> ---
>>      This is a bug fix for Xen 4.4. Without this patch we can't support guest
>>      that doesn't have the same behavior as Linux to handle GICC interface.
>>      theses bits are not modified by them.
> I'd say we pretty much have to take this -- otherwise some guest can
> break things for everyone else by writing to GICC registers.
>
> I've had a look at the GICH register list and I think we correctly
> switch everything else.

It looks that way to me as well:

Release-acked-by: George Dunlap <george.dunlap@eu.citrix.com>