Re: [PATCH for-next 2/4] RDMA/hns: Add IOMMU enable support in hip08

Robin Murphy
2017-10-12T12:59:11Z

On 12/10/17 13:31, Wei Hu (Xavier) wrote:
>
>
> On 2017/10/1 0:10, Leon Romanovsky wrote:
>> On Sat, Sep 30, 2017 at 05:28:59PM +0800, Wei Hu (Xavier) wrote:
>>> If the IOMMU is enabled, the length of sg obtained from
>>> __iommu_map_sg_attrs is not 4kB. When the IOVA is set with the sg
>>> dma address, the IOVA will not be page continuous. and the VA
>>> returned from dma_alloc_coherent is a vmalloc address. However,
>>> the VA obtained by the page_address is a discontinuous VA. Under
>>> these circumstances, the IOVA should be calculated based on the
>>> sg length, and record the VA returned from dma_alloc_coherent
>>> in the struct of hem.
>>>
>>> Signed-off-by: Wei Hu (Xavier) <xavier.huwei-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>>> Signed-off-by: Shaobo Xu <xushaobo2-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>>> Signed-off-by: Lijun Ou <oulijun-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
>>> ---
>> Doug,
>>
>> I didn't invest time in reviewing it, but having "is_vmalloc_addr" in
>> driver code to deal with dma_alloc_coherent is most probably wrong.
>>
>> Thanks
> Hi,  Leon & Doug
>     We refered the function named __ttm_dma_alloc_page in the kernel
> code as below:
>     And there are similar methods in bch_bio_map and mem_to_page
> functions in current 4.14-rcx.
>
>         static struct dma_page *__ttm_dma_alloc_page(struct dma_pool *pool)
>         {
>             struct dma_page *d_page;
>
>             d_page = kmalloc(sizeof(struct dma_page), GFP_KERNEL);
>             if (!d_page)
>                 return NULL;
>
>             d_page->vaddr = dma_alloc_coherent(pool->dev, pool->size,
>                                &d_page->dma,
>                                    pool->gfp_flags);
>             if (d_page->vaddr) {
>                 if (is_vmalloc_addr(d_page->vaddr))
>                     d_page->p = vmalloc_to_page(d_page->vaddr);
>                 else
>                     d_page->p = virt_to_page(d_page->vaddr);

There are cases on various architectures where neither of those is
right. Whether those actually intersect with TTM or RDMA use-cases is
another matter, of course.

What definitely is a problem is if you ever take that page and end up
accessing it through any virtual address other than the one explicitly
returned by dma_alloc_coherent(). That can blow the coherency wide open
and invite data loss, right up to killing the whole system with a
machine check on certain architectures.

Robin.

>             } else {
>                 kfree(d_page);
>                 d_page = NULL;
>             }
>             return d_page;
>         }
>
>     Regards
> Wei Hu
>>
>>>   drivers/infiniband/hw/hns/hns_roce_alloc.c |  5 ++++-
>>>   drivers/infiniband/hw/hns/hns_roce_hem.c   | 30
>>> +++++++++++++++++++++++++++---
>>>   drivers/infiniband/hw/hns/hns_roce_hem.h   |  6 ++++++
>>>   drivers/infiniband/hw/hns/hns_roce_hw_v2.c | 22 +++++++++++++++-------
>>>   4 files changed, 52 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_alloc.c
>>> b/drivers/infiniband/hw/hns/hns_roce_alloc.c
>>> index 3e4c525..a69cd4b 100644
>>> --- a/drivers/infiniband/hw/hns/hns_roce_alloc.c
>>> +++ b/drivers/infiniband/hw/hns/hns_roce_alloc.c
>>> @@ -243,7 +243,10 @@ int hns_roce_buf_alloc(struct hns_roce_dev
>>> *hr_dev, u32 size, u32 max_direct,
>>>                   goto err_free;
>>>
>>>               for (i = 0; i < buf->nbufs; ++i)
>>> -                pages[i] = virt_to_page(buf->page_list[i].buf);
>>> +                pages[i] =
>>> +                    is_vmalloc_addr(buf->page_list[i].buf) ?
>>> +                    vmalloc_to_page(buf->page_list[i].buf) :
>>> +                    virt_to_page(buf->page_list[i].buf);
>>>
>>>               buf->direct.buf = vmap(pages, buf->nbufs, VM_MAP,
>>>                              PAGE_KERNEL);
>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hem.c
>>> b/drivers/infiniband/hw/hns/hns_roce_hem.c
>>> index 8388ae2..4a3d1d4 100644
>>> --- a/drivers/infiniband/hw/hns/hns_roce_hem.c
>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hem.c
>>> @@ -200,6 +200,7 @@ static struct hns_roce_hem
>>> *hns_roce_alloc_hem(struct hns_roce_dev *hr_dev,
>>>                              gfp_t gfp_mask)
>>>   {
>>>       struct hns_roce_hem_chunk *chunk = NULL;
>>> +    struct hns_roce_vmalloc *vmalloc;
>>>       struct hns_roce_hem *hem;
>>>       struct scatterlist *mem;
>>>       int order;
>>> @@ -227,6 +228,7 @@ static struct hns_roce_hem
>>> *hns_roce_alloc_hem(struct hns_roce_dev *hr_dev,
>>>               sg_init_table(chunk->mem, HNS_ROCE_HEM_CHUNK_LEN);
>>>               chunk->npages = 0;
>>>               chunk->nsg = 0;
>>> +            memset(chunk->vmalloc, 0, sizeof(chunk->vmalloc));
>>>               list_add_tail(&chunk->list, &hem->chunk_list);
>>>           }
>>>
>>> @@ -243,7 +245,15 @@ static struct hns_roce_hem
>>> *hns_roce_alloc_hem(struct hns_roce_dev *hr_dev,
>>>           if (!buf)
>>>               goto fail;
>>>
>>> -        sg_set_buf(mem, buf, PAGE_SIZE << order);
>>> +        if (is_vmalloc_addr(buf)) {
>>> +            vmalloc = &chunk->vmalloc[chunk->npages];
>>> +            vmalloc->is_vmalloc_addr = true;
>>> +            vmalloc->vmalloc_addr = buf;
>>> +            sg_set_page(mem, vmalloc_to_page(buf),
>>> +                    PAGE_SIZE << order, offset_in_page(buf));
>>> +        } else {
>>> +            sg_set_buf(mem, buf, PAGE_SIZE << order);
>>> +        }
>>>           WARN_ON(mem->offset);
>>>           sg_dma_len(mem) = PAGE_SIZE << order;
>>>
>>> @@ -262,17 +272,25 @@ static struct hns_roce_hem
>>> *hns_roce_alloc_hem(struct hns_roce_dev *hr_dev,
>>>   void hns_roce_free_hem(struct hns_roce_dev *hr_dev, struct
>>> hns_roce_hem *hem)
>>>   {
>>>       struct hns_roce_hem_chunk *chunk, *tmp;
>>> +    void *cpu_addr;
>>>       int i;
>>>
>>>       if (!hem)
>>>           return;
>>>
>>>       list_for_each_entry_safe(chunk, tmp, &hem->chunk_list, list) {
>>> -        for (i = 0; i < chunk->npages; ++i)
>>> +        for (i = 0; i < chunk->npages; ++i) {
>>> +            if (chunk->vmalloc[i].is_vmalloc_addr)
>>> +                cpu_addr = chunk->vmalloc[i].vmalloc_addr;
>>> +            else
>>> +                cpu_addr =
>>> +                   lowmem_page_address(sg_page(&chunk->mem[i]));
>>> +
>>>               dma_free_coherent(hr_dev->dev,
>>>                      chunk->mem[i].length,
>>> -                   lowmem_page_address(sg_page(&chunk->mem[i])),
>>> +                   cpu_addr,
>>>                      sg_dma_address(&chunk->mem[i]));
>>> +        }
>>>           kfree(chunk);
>>>       }
>>>
>>> @@ -774,6 +792,12 @@ void *hns_roce_table_find(struct hns_roce_dev
>>> *hr_dev,
>>>
>>>               if (chunk->mem[i].length > (u32)offset) {
>>>                   page = sg_page(&chunk->mem[i]);
>>> +                if (chunk->vmalloc[i].is_vmalloc_addr) {
>>> +                    mutex_unlock(&table->mutex);
>>> +                    return page ?
>>> +                        chunk->vmalloc[i].vmalloc_addr
>>> +                        + offset : NULL;
>>> +                }
>>>                   goto out;
>>>               }
>>>               offset -= chunk->mem[i].length;
>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hem.h
>>> b/drivers/infiniband/hw/hns/hns_roce_hem.h
>>> index af28bbf..62d712a 100644
>>> --- a/drivers/infiniband/hw/hns/hns_roce_hem.h
>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hem.h
>>> @@ -72,11 +72,17 @@ enum {
>>>        HNS_ROCE_HEM_PAGE_SIZE  = 1 << HNS_ROCE_HEM_PAGE_SHIFT,
>>>   };
>>>
>>> +struct hns_roce_vmalloc {
>>> +    bool    is_vmalloc_addr;
>>> +    void    *vmalloc_addr;
>>> +};
>>> +
>>>   struct hns_roce_hem_chunk {
>>>       struct list_head     list;
>>>       int             npages;
>>>       int             nsg;
>>>       struct scatterlist     mem[HNS_ROCE_HEM_CHUNK_LEN];
>>> +    struct hns_roce_vmalloc     vmalloc[HNS_ROCE_HEM_CHUNK_LEN];
>>>   };
>>>
>>>   struct hns_roce_hem {
>>> diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>> b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>> index b99d70a..9e19bf1 100644
>>> --- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>> +++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
>>> @@ -1093,9 +1093,11 @@ static int hns_roce_v2_write_mtpt(void
>>> *mb_buf, struct hns_roce_mr *mr,
>>>   {
>>>       struct hns_roce_v2_mpt_entry *mpt_entry;
>>>       struct scatterlist *sg;
>>> +    u64 page_addr = 0;
>>>       u64 *pages;
>>> +    int i = 0, j = 0;
>>> +    int len = 0;
>>>       int entry;
>>> -    int i;
>>>
>>>       mpt_entry = mb_buf;
>>>       memset(mpt_entry, 0, sizeof(*mpt_entry));
>>> @@ -1153,14 +1155,20 @@ static int hns_roce_v2_write_mtpt(void
>>> *mb_buf, struct hns_roce_mr *mr,
>>>
>>>       i = 0;
>>>       for_each_sg(mr->umem->sg_head.sgl, sg, mr->umem->nmap, entry) {
>>> -        pages[i] = ((u64)sg_dma_address(sg)) >> 6;
>>> -
>>> -        /* Record the first 2 entry directly to MTPT table */
>>> -        if (i >= HNS_ROCE_V2_MAX_INNER_MTPT_NUM - 1)
>>> -            break;
>>> -        i++;
>>> +        len = sg_dma_len(sg) >> PAGE_SHIFT;
>>> +        for (j = 0; j < len; ++j) {
>>> +            page_addr = sg_dma_address(sg) +
>>> +                    (j << mr->umem->page_shift);
>>> +            pages[i] = page_addr >> 6;
>>> +
>>> +            /* Record the first 2 entry directly to MTPT table */
>>> +            if (i >= HNS_ROCE_V2_MAX_INNER_MTPT_NUM - 1)
>>> +                goto found;
>>> +            i++;
>>> +        }
>>>       }
>>>
>>> +found:
>>>       mpt_entry->pa0_l = cpu_to_le32(lower_32_bits(pages[0]));
>>>       roce_set_field(mpt_entry->byte_56_pa0_h, V2_MPT_BYTE_56_PA0_H_M,
>>>                  V2_MPT_BYTE_56_PA0_H_S,
>>> --
>>> 1.9.1
>>>
>
>
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