On 11.03.20 09:41, David Hildenbrand wrote:
> On 11.03.20 09:33, Christian Borntraeger wrote:
>> The sie block must be aligned to 512 bytes. Mark it as such.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
>> ---
>> arch/s390/include/asm/kvm_host.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
>> index 0ea82152d2f7..2d50f6c432e2 100644
>> --- a/arch/s390/include/asm/kvm_host.h
>> +++ b/arch/s390/include/asm/kvm_host.h
>> @@ -344,7 +344,7 @@ struct kvm_s390_sie_block {
>> __u64 itdba; /* 0x01e8 */
>> __u64 riccbd; /* 0x01f0 */
>> __u64 gvrd; /* 0x01f8 */
>> -} __attribute__((packed));
>> +} __packed __aligned(512);
>>
>
> I guess there is no change in the code/behavior, because we always place
> into well defined spots within a page.
In theory gcc can generate code that relies on that alignment. For example
load relative long requires double word alignment. Or some atomic instructions.
This could - in theory - generate better code.
>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
>
>
