Re: [Xen-devel] [PATCH v1] swiotlb-xen: implement xen_swiotlb_dma_mmap callback

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Mon, 12 May 2014, Oleksandr Dmytryshyn wrote:
> On Fri, May 9, 2014 at 5:50 PM, Stefano Stabellini
> <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> > On Mon, 28 Apr 2014, Oleksandr Dmytryshyn wrote:
> >> Hi, Stefano.
> >>
> >> Can You please confirm that this implementation of the
> >> xen_swiotlb_dma_mmap is correct?
> >
> > Hi Oleksandr,
> > sorry for the delay in my reply.
> >
> > The patch is OK. It needs an Ack from the other Xen x86 maintainers too.
> > See this thread as reference:
> >
> > http://marc.info/?l=xen-devel&m=139586321124533
> >
> >
> >> Oleksandr Dmytryshyn | Product Engineering and Development
> >> GlobalLogic
> >> M +38.067.382.2525
> >> www.globallogic.com
> >>
> >> http://www.globallogic.com/email_disclaimer.txt
> >>
> >>
> >> On Tue, Apr 8, 2014 at 3:08 PM, Oleksandr Dmytryshyn
> >> <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx> wrote:
> >> > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> >> >
> >> > This function creates userspace mapping for the DMA-coherent memory.
> >> >
> >> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> >> > Signed-off-by: Oleksandr Dmytryshyn 
> >> > <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>
> >> > ---
> >> >  arch/arm/xen/mm.c         |  1 +
> >> >  drivers/xen/swiotlb-xen.c | 36 ++++++++++++++++++++++++++++++++++++
> >> >  include/xen/swiotlb-xen.h |  5 +++++
> >> >  3 files changed, 42 insertions(+)
> >> >
> >> > diff --git a/arch/arm/xen/mm.c b/arch/arm/xen/mm.c
> >> > index b0e77de..91408b1 100644
> >> > --- a/arch/arm/xen/mm.c
> >> > +++ b/arch/arm/xen/mm.c
> >> > @@ -48,6 +48,7 @@ static struct dma_map_ops xen_swiotlb_dma_ops = {
> >> >         .sync_sg_for_device = xen_swiotlb_sync_sg_for_device,
> >> >         .map_sg = xen_swiotlb_map_sg_attrs,
> >> >         .unmap_sg = xen_swiotlb_unmap_sg_attrs,
> >> > +       .mmap = xen_swiotlb_dma_mmap,
> >> >         .map_page = xen_swiotlb_map_page,
> >> >         .unmap_page = xen_swiotlb_unmap_page,
> >> >         .dma_supported = xen_swiotlb_dma_supported,
> >> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> >> > index 5403855..acf0c06 100644
> >> > --- a/drivers/xen/swiotlb-xen.c
> >> > +++ b/drivers/xen/swiotlb-xen.c
> >> > @@ -407,6 +407,42 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, 
> >> > struct page *page,
> >> >  EXPORT_SYMBOL_GPL(xen_swiotlb_map_page);
> >> >
> >> >  /*
> >> > + * Create userspace mapping for the DMA-coherent memory.
> >> > + */
> >> > +int xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> >> > +                        void *cpu_addr, dma_addr_t dma_addr, size_t 
> >> > size,
> >> > +                        struct dma_attrs *attrs)
> >> > +{
> >> > +       int ret = -ENXIO;
> >> > +       unsigned long nr_vma_pages = (vma->vm_end - vma->vm_start) >> 
> >> > PAGE_SHIFT;
> >> > +       unsigned long nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT;
> >> > +       unsigned long pfn = PFN_DOWN(xen_bus_to_phys(dma_addr));
> >> > +       unsigned long off = vma->vm_pgoff;
> >> > +       pgprot_t prot = vma->vm_page_prot;
> >> > +
> >> > +       prot = dma_get_attr(DMA_ATTR_WRITE_COMBINE, attrs) ?
> >> > +                           pgprot_writecombine(prot) :
> >> > +                           pgprot_dmacoherent(prot);
> >> > +
> >> > +       vma->vm_page_prot = prot;
> >> > +
> >> > +       if (dma_mmap_from_coherent(dev, vma, cpu_addr, size, &ret))
> >> > +               return ret;
> >> > +
> >> > +       if (off < nr_pages && nr_vma_pages <= (nr_pages - off)) {
> >> > +               ret = remap_pfn_range(vma, vma->vm_start,
> >> > +                                       pfn + off,
> >> > +                                       vma->vm_end - vma->vm_start,
> >> > +                                       vma->vm_page_prot);
> >> > +       }
> >> > +
> >> > +       return ret;
> >> > +}
> >> > +EXPORT_SYMBOL_GPL(xen_swiotlb_dma_mmap);
> >> > +
> >> > +/*
> >> >   * Unmap a single streaming mode DMA translation.  The dma_addr and 
> >> > size must
> >> >   * match what was provided for in a previous xen_swiotlb_map_page call. 
> >> >  All
> >> >   * other usages are undefined.
> >> > diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> >> > index 7b64465..930fa94 100644
> >> > --- a/include/xen/swiotlb-xen.h
> >> > +++ b/include/xen/swiotlb-xen.h
> >> > @@ -15,6 +15,11 @@ xen_swiotlb_free_coherent(struct device *hwdev, 
> >> > size_t size,
> >> >                           void *vaddr, dma_addr_t dma_handle,
> >> >                           struct dma_attrs *attrs);
> >> >
> >> > +extern int
> >> > +xen_swiotlb_dma_mmap(struct device *dev, struct vm_area_struct *vma,
> >> > +                    void *cpu_addr, dma_addr_t dma_addr, size_t size,
> >> > +                    struct dma_attrs *attrs);
> >> > +
> >> >  extern dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page 
> >> > *page,
> >> >                                        unsigned long offset, size_t size,
> >> >                                        enum dma_data_direction dir,
> >> > --
> >> > 1.8.2.rc2
> >> >
> >>
> 
> Hi, Stefano.
> 
> Thank You for reply.
> 
> I'll look into that thread.

Actually the thread I linked was for the other maintainers in CC, to
better understand why we need this :-)

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