Re: [PATCH 1/1] RDMA/irdma: Add support for dmabuf pin memory regions

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

在 2023/1/4 7:11, Jason Gunthorpe 写道:
> On Mon, Jan 02, 2023 at 08:34:33PM -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>
>> ---
>>   drivers/infiniband/hw/irdma/verbs.c | 158 ++++++++++++++++++++++++++++
>>   1 file changed, 158 insertions(+)
>>
>> diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
>> index f6973ea55eda..76dc6e65930a 100644
>> --- a/drivers/infiniband/hw/irdma/verbs.c
>> +++ b/drivers/infiniband/hw/irdma/verbs.c
>> @@ -2912,6 +2912,163 @@ static struct ib_mr *irdma_reg_user_mr(struct ib_pd *pd, u64 start, u64 len,
>>   	return ERR_PTR(err);
>>   }
>>   
>> +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_ucontext *ucontext;
>> +	struct irdma_pble_alloc *palloc;
>> +	struct irdma_pbl *iwpbl;
>> +	struct irdma_mr *iwmr;
>> +	struct irdma_mem_reg_req req;
>> +	u32 total, stag = 0;
>> +	u8 shadow_pgcnt = 1;
>> +	bool use_pbles = false;
>> +	unsigned long flags;
>> +	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);
>> +	}
>> +
>> +	if (ib_copy_from_udata(&req, udata, min(sizeof(req), udata->inlen))) {
>> +		ib_umem_release(&umem_dmabuf->umem);
>> +		return ERR_PTR(-EFAULT);
>> +	}
>> +
>> +	iwmr = kzalloc(sizeof(*iwmr), GFP_KERNEL);
>> +	if (!iwmr) {
>> +		ib_umem_release(&umem_dmabuf->umem);
>> +		return ERR_PTR(-ENOMEM);
>> +	}
>> +
>> +	iwpbl = &iwmr->iwpbl;
>> +	iwpbl->iwmr = iwmr;
>> +	iwmr->region = &umem_dmabuf->umem;
>> +	iwmr->ibmr.pd = pd;
>> +	iwmr->ibmr.device = pd->device;
>> +	iwmr->ibmr.iova = virt;
>> +	iwmr->page_size = PAGE_SIZE;
>> +
>> +	if (req.reg_type == IRDMA_MEMREG_TYPE_MEM) {
>> +		iwmr->page_size = ib_umem_find_best_pgsz(iwmr->region,
>> +							 iwdev->rf->sc_dev.hw_attrs.page_size_cap,
>> +							 virt);
> You can't call rdma_umem_for_each_dma_block() without also calling
> this function to validate that the page_size passed to
> rdma_umem_for_each_dma_block() is correct.
Got it. I will fix it in the latest commit.
>
> This seems to be an existing bug, please fix it.
>
> Also, is there a reason this code is all duplicated from
> irdma_reg_user_mr? Please split things up like the other drivers to
> obtain the umem then use shared code to process the umem as required.

Got it.

Zhu Yanjun

>
> Jason