[BUG]SMMU-V3 queue need no-cache memory

[sisyphean <sisyphean@zlw.email>]

Hi,

    I try to run XEN on my ARM board(Sorry, for some commercial 
reasons, I can't tell you
    on which platform I run XEN)  and enable SMMU-V3, but all cmds in 
cmdq failed when XEN started.
    After using the debugger to track debugging, the reason for this 
problem is that
    the queue in the smmu-v3 driver is not no-cache, so after the 
function arm_smmu_cmdq_build_cmd
    is executed, the cmd is still in cache.Therefore, the SMMU-V3 
hardware cannot obtain the correct cmd
    from the memory for execution.

    The temporary solution I use is to execute function clean_dcache 
every time cmd is copied to cmdq
    in function queue_write. But it is obvious that this will seriously 
affect the efficiency.
    I have not found the method of malloc no-cache memory in XEN. Is 
this method not implemented?
    The XEN version I am running is RELEASE-4.16.2.

    English is not my native language; please excuse typing errors.

Cheers,

--
Sisyphean