Re: [PATCHv3 for-next 1/1] RDMA/irdma: Add support for dmabuf pin memory regions

[Yanjun Zhu <yanjun.zhu@linux.dev>]

在 2023/1/5 21:37, Jason Gunthorpe 写道:
> On Thu, Jan 05, 2023 at 05:37:10PM -0500, Zhu Yanjun wrote:
>> From: Zhu Yanjun <yanjun.zhu@linux.dev>
>>
>> This is a followup to the EFA dmabuf[1]. Irdma driver currently does
>> not support on-demand-paging(ODP). So it uses habanalabs as the
>> dmabuf exporter, and irdma as the importer to allow for peer2peer
>> access through libibverbs.
>>
>> In this commit, the function ib_umem_dmabuf_get_pinned() is used.
>> This function is introduced in EFA dmabuf[1] which allows the driver
>> to get a dmabuf umem which is pinned and does not require move_notify
>> callback implementation. The returned umem is pinned and DMA mapped
>> like standard cpu umems, and is released through ib_umem_release().
>>
>> [1]https://lore.kernel.org/lkml/20211007114018.GD2688930@ziepe.ca/t/
>>
>> Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
>> ---
>> V2->V3: Simplify the function by removing QP and CQ handling;
>> V1->V2: Fix the build warning by adding a static;
>> ---
>>   drivers/infiniband/hw/irdma/verbs.c | 97 +++++++++++++++++++++++++++++
>>   1 file changed, 97 insertions(+)
>>
>> diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
>> index f6973ea55eda..7028b8af87b9 100644
>> --- a/drivers/infiniband/hw/irdma/verbs.c
>> +++ b/drivers/infiniband/hw/irdma/verbs.c
>> @@ -2912,6 +2912,102 @@ static struct ib_mr *irdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 len,
>>   	return ERR_PTR(err);
>>   }
>>   
>> +static struct ib_mr *irdma_reg_user_mr_dmabuf(struct ib_pd *pd, u64 start,
>> +					      u64 len, u64 virt,
>> +					      int fd, int access,
>> +					      struct ib_udata *udata)
>> +{
>> +	struct irdma_device *iwdev = to_iwdev(pd->device);
>> +	struct irdma_pble_alloc *palloc;
>> +	struct irdma_pbl *iwpbl;
>> +	struct irdma_mr *iwmr;
>> +	u32 stag = 0;
>> +	bool use_pbles = false;
>> +	int err = -EINVAL;
>> +	struct ib_umem_dmabuf *umem_dmabuf;
>> +
>> +	if (len > iwdev->rf->sc_dev.hw_attrs.max_mr_size)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (udata->inlen < IRDMA_MEM_REG_MIN_REQ_LEN)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	umem_dmabuf = ib_umem_dmabuf_get_pinned(pd->device, start, len, fd,
>> +						access);
>> +	if (IS_ERR(umem_dmabuf)) {
>> +		err = PTR_ERR(umem_dmabuf);
>> +		ibdev_dbg(&iwdev->ibdev, "Failed to get dmabuf umem[%d]\n", err);
>> +		return ERR_PTR(err);
>> +	}
>> +
>> +	iwmr = kzalloc(sizeof(*iwmr), GFP_KERNEL);
>> +	if (!iwmr) {
>> +		ib_umem_release(&umem_dmabuf->umem);
>> +		return ERR_PTR(-ENOMEM);
>> +	}
> 
> again, please don't duplicate all this code, refactor the mr code so
> it can be shared.
Got it. I will refactor the mr code and split the shared code into 
several helper functions. After the commits are merged, I will continue 
to add the support of dmabuf with the helper functions.

Zhu Yanjun
> 
> Jason