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

[Leon Romanovsky <leon@kernel.org>]

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On Tue, Nov 07, 2017 at 10:45:29AM +0800, Wei Hu (Xavier) wrote:
>
>
> On 2017/11/1 20:26, Robin Murphy wrote:
> > On 01/11/17 07:46, Wei Hu (Xavier) wrote:
> >>
> >> On 2017/10/12 20:59, Robin Murphy wrote:
> >>> 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@huawei.com>
> >>>>>> Signed-off-by: Shaobo Xu <xushaobo2@huawei.com>
> >>>>>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
> >>>>>> ---
> >>>>> 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.
> >> Hi, Robin
> >>     Thanks for your comment.
> >>
> >>     We have one problem and the related code as below.
> >>     1. call dma_alloc_coherent function  serval times to alloc memory.
> >>     2. vmap the allocated memory pages.
> >>     3. software access memory by using the return virt addr of vmap
> >>         and hardware using the dma addr of dma_alloc_coherent.
> > The simple answer is "don't do that". Seriously. dma_alloc_coherent()
> > gives you a CPU virtual address and a DMA address with which to access
> > your buffer, and that is the limit of what you may infer about it. You
> > have no guarantee that the virtual address is either in the linear map
> > or vmalloc, and not some other special place. You have no guarantee that
> > the underlying memory even has an associated struct page at all.
> >
> >>     When IOMMU is disabled in ARM64 architecture, we use virt_to_page()
> >>     before vmap(), it works. And when IOMMU is enabled using
> >>     virt_to_page() will cause calltrace later, we found the return
> >>     addr of dma_alloc_coherent is vmalloc addr, so we add the
> >>     condition judgement statement as below, it works.
> >>         for (i = 0; i < buf->nbufs; ++i)
> >>                 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);
> >>     Can you give us suggestion? better method?
> > Oh my goodness, having now taken a closer look at this driver, I'm lost
> > for words in disbelief. To pick just one example:
> >
> > 	u32 bits_per_long = BITS_PER_LONG;
> > 	...
> > 	if (bits_per_long == 64) {
> > 		/* memory mapping nonsense */
> > 	}
> >
> > WTF does the size of a long have to do with DMA buffer management!?
> >
> > Of course I can guess that it might be trying to make some tortuous
> > inference about vmalloc space being constrained on 32-bit platforms, but
> > still...
> >
> >>     The related code as below:
> >>         buf->page_list = kcalloc(buf->nbufs, sizeof(*buf->page_list),
> >>                      GFP_KERNEL);
> >>         if (!buf->page_list)
> >>             return -ENOMEM;
> >>
> >>         for (i = 0; i < buf->nbufs; ++i) {
> >>             buf->page_list[i].buf = dma_alloc_coherent(dev,
> >>                                   page_size, &t,
> >>                                   GFP_KERNEL);
> >>             if (!buf->page_list[i].buf)
> >>                 goto err_free;
> >>
> >>             buf->page_list[i].map = t;
> >>             memset(buf->page_list[i].buf, 0, page_size);
> >>         }
> >>
> >>         pages = kmalloc_array(buf->nbufs, sizeof(*pages),
> >>                           GFP_KERNEL);
> >>         if (!pages)
> >>                 goto err_free;
> >>
> >>         for (i = 0; i < buf->nbufs; ++i)
> >>                 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);
> >>         kfree(pages);
> >>         if (!buf->direct.buf)
> >>                 goto err_free;
> > OK, this is complete crap. As above, you cannot assume that a struct
> > page even exists; even if it does you cannot assume that using a
> > PAGE_KERNEL mapping will not result in mismatched attributes,
> > unpredictable behaviour and data loss. Trying to remap coherent DMA
> > allocations like this is just egregiously wrong.
> >
> > What I do like is that you can seemingly fix all this by simply deleting
> > hns_roce_buf::direct and all the garbage code related to it, and using
> > the page_list entries consistently because the alternate paths involving
> > those appear to do the right thing already.
> >
> > That is, of course, assuming that the buffers involved can be so large
> > that it's not practical to just always make a single allocation and
> > fragment it into multiple descriptors if the hardware does have some
> > maximum length constraint - frankly I'm a little puzzled by the
> > PAGE_SIZE * 2 threshold, given that that's not a fixed size.
> >
> > Robin.
> Hi，Robin
>
>     We reconstruct the code as below:
>             It replaces dma_alloc_coherent with __get_free_pages and
> dma_map_single
>     functions. So, we can vmap serveral ptrs returned by
> __get_free_pages, right?

Most probably not, you should get rid of your virt_to_page/vmap calls.

Thanks

>
>
>         buf->page_list = kcalloc(buf->nbufs, sizeof(*buf->page_list),
>                      GFP_KERNEL);
>         if (!buf->page_list)
>             return -ENOMEM;
>
>         for (i = 0; i < buf->nbufs; ++i) {
> 		ptr = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
> 					       get_order(page_size));
> 		if (!ptr) {
> 			dev_err(dev, "Alloc pages error.\n");
> 			goto err_free;
> 		}
>
> 		t = dma_map_single(dev, ptr, page_size,
> 				   DMA_BIDIRECTIONAL);
> 		if (dma_mapping_error(dev, t)) {
> 			dev_err(dev, "DMA mapping error.\n");
> 			free_pages((unsigned long)ptr,
> 				   get_order(page_size));
> 			goto err_free;
> 		}
>
> 		buf->page_list[i].buf = ptr;
> 		buf->page_list[i].map = t;
>         }
>
>         pages = kmalloc_array(buf->nbufs, sizeof(*pages),
>                           GFP_KERNEL);
>         if (!pages)
>                 goto err_free;
>
>         for (i = 0; i < buf->nbufs; ++i)
>                 pages[i] = virt_to_page(buf->page_list[i].buf);
>
>         buf->direct.buf = vmap(pages, buf->nbufs, VM_MAP,
>                            PAGE_KERNEL);
>         kfree(pages);
>         if (!buf->direct.buf)
>                 goto err_free;
>
>
>     Regards
> Wei Hu
> >>     Regards
> >> Wei Hu
> >>>>             } 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
> >>>>>>
> >>>> _______________________________________________
> >>>> iommu mailing list
> >>>> iommu@lists.linux-foundation.org
> >>>> https://lists.linuxfoundation.org/mailman/listinfo/iommu
> >>> .
> >>>
> >>
> > --
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> >
> > .
> >
>
>
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