Re: [PATCH v5 02/12] xen/arm: add SVE vector length field to the domain

[Luca Fancellu <Luca.Fancellu@xxxxxxx>]

> 
> 
>> 
>>>> Can we move this somewhere else to avoid adding extra padding? Also 
>>>> shouldn't this be protected with #ifdef CONFIG_ARM_64 to make clear this 
>>>> is not supported on Xen 32-bit?
>>> Yes, I’ll move it and protect with CONFIG_ARM_64, is it ok for you if I 
>>> move it after:
>>> /* Monitor options */
>>> struct {
>>>    uint8_t privileged_call_enabled : 1;
>>> } monitor;
>> 
>> Please check the padding with "pahole". If possible, it would be better to 
>> re-use an existing one.
> 
> Ok I’ll try to use the tool

I’ve managed to use the tool, the field seems already in a good spot:

struct arch_domain {
        enum domain_type           type;                 /*     0     4 */
        uint8_t                    sve_vl;               /*     4     1 */

        /* XXX 3 bytes hole, try to pack */

        struct p2m_domain          p2m;                  /*     8   328 */
        /* --- cacheline 5 boundary (320 bytes) was 16 bytes ago --- */
        struct hvm_domain          hvm;                  /*   336   312 */
        /* --- cacheline 10 boundary (640 bytes) was 8 bytes ago --- */
        struct paging_domain       paging;               /*   648    32 */
        struct vmmio               vmmio;                /*   680    32 */
        /* --- cacheline 11 boundary (704 bytes) was 8 bytes ago --- */
        unsigned int               rel_priv;             /*   712     4 */

        /* XXX 4 bytes hole, try to pack */

        struct {
                uint64_t           offset;               /*   720     8 */
                s_time_t           nanoseconds;          /*   728     8 */
        } virt_timer_base;                               /*   720    16 */
        struct vgic_dist           vgic;                 /*   736   200 */

        /* XXX last struct has 2 bytes of padding */

        /* --- cacheline 14 boundary (896 bytes) was 40 bytes ago --- */
        struct vuart               vuart;                /*   936    32 */
        /* --- cacheline 15 boundary (960 bytes) was 8 bytes ago --- */
        unsigned int               evtchn_irq;           /*   968     4 */
        struct {
                uint8_t            privileged_call_enabled:1; /*   972: 0  1 */
        } monitor;                                       /*   972     1 */

        /* XXX 3 bytes hole, try to pack */

        struct vpl011              vpl011;               /*   976    72 */

        /* size: 1152, cachelines: 18, members: 13 */
        /* sum members: 1038, holes: 3, sum holes: 10 */
        /* padding: 104 */
        /* paddings: 1, sum paddings: 2 */
} __attribute__((__aligned__(128)));

> 
>> 
>> Cheers,
>> 
>> -- 
>> Julien Grall