Messages in this thread | | | Subject | Re: [PATCH 08/10] swiotlb-xen: introduce phys_to_dma/dma_to_phys translations | From | Julien Grall <> | Date | Thu, 21 May 2020 09:07:53 +0100 |
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Hi,
On 21/05/2020 00:45, Stefano Stabellini wrote: > From: Stefano Stabellini <stefano.stabellini@xilinx.com> > > Call dma_to_phys in is_xen_swiotlb_buffer. > Call phys_to_dma in xen_phys_to_bus. > Call dma_to_phys in xen_bus_to_phys. > > Everything is taken care of by these changes except for > xen_swiotlb_alloc_coherent and xen_swiotlb_free_coherent, which need a > few explicit phys_to_dma/dma_to_phys calls.
The commit message explains what the code is doing but doesn't explain why this is needed.
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> > --- > drivers/xen/swiotlb-xen.c | 20 ++++++++++++-------- > 1 file changed, 12 insertions(+), 8 deletions(-) > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index c50448fd9b75..d011c4c7aa72 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -64,14 +64,16 @@ static inline dma_addr_t xen_phys_to_bus(struct device *dev, phys_addr_t paddr) > > dma |= paddr & ~XEN_PAGE_MASK; > > - return dma; > + return phys_to_dma(dev, dma); > } > > -static inline phys_addr_t xen_bus_to_phys(struct device *dev, dma_addr_t baddr) > +static inline phys_addr_t xen_bus_to_phys(struct device *dev, > + dma_addr_t dma_addr) > { > + phys_addr_t baddr = dma_to_phys(dev, dma_addr); > unsigned long xen_pfn = bfn_to_pfn(XEN_PFN_DOWN(baddr)); > - dma_addr_t dma = (dma_addr_t)xen_pfn << XEN_PAGE_SHIFT; > - phys_addr_t paddr = dma; > + phys_addr_t paddr = (xen_pfn << XEN_PAGE_SHIFT) | > + (baddr & ~XEN_PAGE_MASK); > > paddr |= baddr & ~XEN_PAGE_MASK; > > @@ -99,7 +101,7 @@ static inline int range_straddles_page_boundary(phys_addr_t p, size_t size) > > static int is_xen_swiotlb_buffer(struct device *dev, dma_addr_t dma_addr) > { > - unsigned long bfn = XEN_PFN_DOWN(dma_addr); > + unsigned long bfn = XEN_PFN_DOWN(dma_to_phys(dev, dma_addr)); > unsigned long xen_pfn = bfn_to_local_pfn(bfn); > phys_addr_t paddr = XEN_PFN_PHYS(xen_pfn); > > @@ -304,11 +306,11 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, > if (hwdev && hwdev->coherent_dma_mask) > dma_mask = hwdev->coherent_dma_mask; > > - /* At this point dma_handle is the physical address, next we are > + /* At this point dma_handle is the dma address, next we are > * going to set it to the machine address. > * Do not use virt_to_phys(ret) because on ARM it doesn't correspond > * to *dma_handle. */ > - phys = *dma_handle; > + phys = dma_to_phys(hwdev, *dma_handle); > dev_addr = xen_phys_to_bus(hwdev, phys); > if (((dev_addr + size - 1 <= dma_mask)) && > !range_straddles_page_boundary(phys, size)) > @@ -319,6 +321,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size, > xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs); > return NULL; > } > + *dma_handle = phys_to_dma(hwdev, *dma_handle); > SetPageXenRemapped(virt_to_page(ret)); > } > memset(ret, 0, size); > @@ -351,7 +354,8 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr, > TestClearPageXenRemapped(pg)) > xen_destroy_contiguous_region(phys, order); > > - xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs); > + xen_free_coherent_pages(hwdev, size, vaddr, phys_to_dma(hwdev, phys), > + attrs); > } > > /* >
Cheers,
-- Julien Grall
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