> We can merge this patch and create a new one for
> xen_swiotlb_free_coherent() later.
> Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> was problematic.
>
> This patch is fine by me.
Good. I'm agreed too. Waiting for Christoph.
пт, 16 июл. 2021 г. в 18:29, Stefano Stabellini :
>
> On Fri, 16 Jul 2021, Roman Skakun wrote:
> > > Technically this looks good. But given that exposing a helper
> > > that does either vmalloc_to_page or virt_to_page is one of the
> > > never ending MM discussions I don't want to get into that discussion
> > > and just keep it local in the DMA code.
> > >
> > > Are you fine with me applying this version?
> >
> > Looks good to me, thanks!
> > But, Stefano asked me about using created helper in the
> > xen_swiotlb_free_coherent()
> > and I created a patch according to this mention.
> >
> > We can merge this patch and create a new one for
> > xen_swiotlb_free_coherent() later.
>
> Yeah, no worries, I didn't know that exposing dma_common_vaddr_to_page
> was problematic.
>
> This patch is fine by me.
>
>
> > пт, 16 июл. 2021 г. в 12:35, Christoph Hellwig :
> > >
> > > Technically this looks good. But given that exposing a helper
> > > that does either vmalloc_to_page or virt_to_page is one of the
> > > never ending MM discussions I don't want to get into that discussion
> > > and just keep it local in the DMA code.
> > >
> > > Are you fine with me applying this version?
> > >
> > > ---
> > > From 40ac971eab89330d6153e7721e88acd2d98833f9 Mon Sep 17 00:00:00 2001
> > > From: Roman Skakun
> > > Date: Fri, 16 Jul 2021 11:39:34 +0300
> > > Subject: dma-mapping: handle vmalloc addresses in
> > > dma_common_{mmap,get_sgtable}
> > >
> > > xen-swiotlb can use vmalloc backed addresses for dma coherent allocations
> > > and uses the common helpers. Properly handle them to unbreak Xen on
> > > ARM platforms.
> > >
> > > Fixes: 1b65c4e5a9af ("swiotlb-xen: use xen_alloc/free_coherent_pages")
> > > Signed-off-by: Roman Skakun
> > > Reviewed-by: Andrii Anisov
> > > [hch: split the patch, renamed the helpers]
> > > Signed-off-by: Christoph Hellwig
> > > ---
> > > kernel/dma/ops_helpers.c | 12 ++--
> > > 1 file changed, 10 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/kernel/dma/ops_helpers.c b/kernel/dma/ops_helpers.c
> > > index 910ae69cae77..af4a6ef48ce0 100644
> > > --- a/kernel/dma/ops_helpers.c
> > > +++ b/kernel/dma/ops_helpers.c
> > > @@ -5,6 +5,13 @@
> > > */
> > > #include
> > >
> > > +static struct page *dma_common_vaddr_to_page(void *cpu_addr)
> > > +{
> > > + if (is_vmalloc_addr(cpu_addr))
> > > + return vmalloc_to_page(cpu_addr);
> > > + return virt_to_page(cpu_addr);
> > > +}
> > > +
> > > /*
> > > * Create scatter-list for the already allocated DMA buffer.
> > > */
> > > @@ -12,7 +19,7 @@ int dma_common_get_sgtable(struct device *dev, struct
> > > sg_table *sgt,
> > > void *cpu_addr, dma_addr_t dma_addr, size_t size,
> > > unsigned long attrs)
> > > {
> > > - struct page *page = virt_to_page(cpu_addr);
> > > + struct page *page = dma_common_vaddr_to_page(cpu_addr);
> > > int ret;
> > >
> > > ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
> > > @@ -32,6 +39,7 @@ int dma_common_mmap(struct device *dev, struct
> > > vm_area_struct *vma,
> > > unsigned long user_count = vma_pages(vma);
> > > unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
> > > unsigned long off = vma->vm_pgoff;
> > > + struct page *page = dma_common_vaddr_to_page(cpu_addr);
> > > int ret = -ENXIO;
> > >
> > > vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
> > > @@ -43,7 +51,7 @@ int dma_common_mmap(struct device *dev, struct
> > > vm_area_struct *vma,
> > > return -ENXIO;
> > >
> > > return remap_pfn_range(vma, vma->vm_start,
> > > - page_to_pfn(virt_to_page(cpu_addr)) +
> > > vma->vm_pgoff,
> > > + page_to_pfn(page) + vma->vm_pgoff,
> > > user_count << PAGE_SHIFT, vma->vm_page_prot);
> > > #else
> > > return -ENXIO;
> > > --
> > > 2.30.2
> > >
> >
> >
> > --
> > Best Regards, Roman.
> >
--
Best Regards, Roman.
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