Messages in this thread Patch in this message | | | Subject | Re: [PATCH v1 02/10] powerpc/kernel/iommu: Align size for IOMMU_PAGE_SIZE on iommu_*_coherent() | From | Alexey Kardashevskiy <> | Date | Sat, 22 Aug 2020 20:07:00 +1000 |
| |
On 18/08/2020 09:40, Leonardo Bras wrote: > Both iommu_alloc_coherent() and iommu_free_coherent() assume that once > size is aligned to PAGE_SIZE it will be aligned to IOMMU_PAGE_SIZE.
The only case when it is not aligned is when IOMMU_PAGE_SIZE > PAGE_SIZE which is unlikely but not impossible, we could configure the kernel for 4K system pages and 64K IOMMU pages I suppose. Do we really want to do this here, or simply put WARN_ON(tbl->it_page_shift > PAGE_SHIFT)? Because if we want the former (==support), then we'll have to align the size up to the bigger page size when allocating/zeroing system pages, etc. Bigger pages are not the case here as I understand it.
> > Update those functions to guarantee alignment with requested size > using IOMMU_PAGE_ALIGN() before doing iommu_alloc() / iommu_free(). > > Also, on iommu_range_alloc(), replace ALIGN(n, 1 << tbl->it_page_shift) > with IOMMU_PAGE_ALIGN(n, tbl), which seems easier to read. > > Signed-off-by: Leonardo Bras <leobras.c@gmail.com> > --- > arch/powerpc/kernel/iommu.c | 17 +++++++++-------- > 1 file changed, 9 insertions(+), 8 deletions(-) > > diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c > index 9704f3f76e63..d7086087830f 100644 > --- a/arch/powerpc/kernel/iommu.c > +++ b/arch/powerpc/kernel/iommu.c > @@ -237,10 +237,9 @@ static unsigned long iommu_range_alloc(struct device *dev, > } > > if (dev) > - boundary_size = ALIGN(dma_get_seg_boundary(dev) + 1, > - 1 << tbl->it_page_shift); > + boundary_size = IOMMU_PAGE_ALIGN(dma_get_seg_boundary(dev) + 1, tbl);
Run checkpatch.pl, should complain about a long line.
> else > - boundary_size = ALIGN(1UL << 32, 1 << tbl->it_page_shift); > + boundary_size = IOMMU_PAGE_ALIGN(1UL << 32, tbl); > /* 4GB boundary for iseries_hv_alloc and iseries_hv_map */ > > n = iommu_area_alloc(tbl->it_map, limit, start, npages, tbl->it_offset, > @@ -858,6 +857,7 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl, > unsigned int order; > unsigned int nio_pages, io_order; > struct page *page; > + size_t size_io = size; > > size = PAGE_ALIGN(size); > order = get_order(size); > @@ -884,8 +884,9 @@ void *iommu_alloc_coherent(struct device *dev, struct iommu_table *tbl, > memset(ret, 0, size); > > /* Set up tces to cover the allocated range */ > - nio_pages = size >> tbl->it_page_shift; > - io_order = get_iommu_order(size, tbl); > + size_io = IOMMU_PAGE_ALIGN(size_io, tbl); > + nio_pages = size_io >> tbl->it_page_shift; > + io_order = get_iommu_order(size_io, tbl); > mapping = iommu_alloc(dev, tbl, ret, nio_pages, DMA_BIDIRECTIONAL, > mask >> tbl->it_page_shift, io_order, 0); > if (mapping == DMA_MAPPING_ERROR) { > @@ -900,11 +901,11 @@ void iommu_free_coherent(struct iommu_table *tbl, size_t size, > void *vaddr, dma_addr_t dma_handle) > { > if (tbl) { > - unsigned int nio_pages; > + size_t size_io = IOMMU_PAGE_ALIGN(size, tbl); > + unsigned int nio_pages = size_io >> tbl->it_page_shift; > > - size = PAGE_ALIGN(size); > - nio_pages = size >> tbl->it_page_shift; > iommu_free(tbl, dma_handle, nio_pages); > +
Unrelated new line.
> size = PAGE_ALIGN(size); > free_pages((unsigned long)vaddr, get_order(size)); > } >
-- Alexey
| |