Re: [RFC PATCH rdma-next 08/10] RDMA/rxe: Implement flush execution in responder side

[lizhijian@xxxxxxxxxxx]

Hi Jason


On 07/01/2022 01:33, Jason Gunthorpe wrote:
> On Thu, Jan 06, 2022 at 06:42:57AM +0000, lizhijian@xxxxxxxxxxx wrote:
>>
>> On 06/01/2022 08:28, Jason Gunthorpe wrote:
>>> On Tue, Dec 28, 2021 at 04:07:15PM +0800, Li Zhijian wrote:
>>>> +	while (length > 0) {
>>>> +		va	= (u8 *)(uintptr_t)buf->addr + offset;
>>>> +		bytes	= buf->size - offset;
>>>> +
>>>> +		if (bytes > length)
>>>> +			bytes = length;
>>>> +
>>>> +		arch_wb_cache_pmem(va, bytes);
>>> So why did we need to check that the va was pmem to call this?
>> Sorry, i didn't get you.
>>
>> I didn't check whether va is pmem, since only MR registered with PERSISTENCE(only pmem can
>> register this access flag) can reach here.
> Yes, that is what I mean,

I'm not sure I understand the *check* you mentioned above.

Current code just dose something like:

if (!sanity_check())
     return;
if (requested_plt == PERSISTENCE)
     va = iova_to_va(iova);
     arch_wb_cache_pmem(va, bytes);
     wmb;
else if (requested_plt == GLOBAL_VISIBILITY)
     wmb();


> why did we need to check anything to call
> this API
As above pseudo code,  it didn't *check* anything as what you said i think.


> - it should work on any CPU mapped address.
Of course, arch_wb_cache_pmem(va, bytes) works on CPU mapped address backing to both dimm and nvdimm,
but not a iova that could refers to user space address.


Thanks
Zhijian



>
> Jason