[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH] xen/swiotlb: add alignment check for dma buffers
On 13.09.2024 16:56, Juergen Gross wrote: > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -78,9 +78,15 @@ static inline int > range_straddles_page_boundary(phys_addr_t p, size_t size) > { > unsigned long next_bfn, xen_pfn = XEN_PFN_DOWN(p); > unsigned int i, nr_pages = XEN_PFN_UP(xen_offset_in_page(p) + size); > + unsigned int order = get_order(size); > > next_bfn = pfn_to_bfn(xen_pfn); > > + /* If buffer is physically aligned, ensure DMA alignment. */ > + if (IS_ALIGNED(p, 1UL << (order + PAGE_SHIFT)) && Why this check? xen_swiotlb_alloc_coherent() guarantees it, while xen_swiotlb_free_coherent() only checks properties of the original allocation. And for xen_swiotlb_map_page() this looks actively wrong to me, in case that function was called with offset non-zero. Unrelated to this, but in related code: xen_swiotlb_alloc_coherent() can't validly use XEN_PAGE_SHIFT, can it (in the way it does at least)? If XEN_PAGE_SHIFT < PAGE_SHIFT, and with order calculated from the latter, the used size will be too small afaict. Jan
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