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SubjectRe: [Xen-devel][RFC 2/3] xen/grant-table: Extend API to work with DMA buffers
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On 05/19/2018 01:19 AM, Boris Ostrovsky wrote:
> On 05/17/2018 04:26 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>
>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>> ---
>> drivers/xen/grant-table.c | 49 +++++++++++++++++++++++++++++++++++++++
>> include/xen/grant_table.h | 7 ++++++
>> 2 files changed, 56 insertions(+)
>>
>> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
>> index bb36b1e1dbcc..c27bcc420575 100644
>> --- a/drivers/xen/grant-table.c
>> +++ b/drivers/xen/grant-table.c
>> @@ -729,6 +729,55 @@ void gnttab_free_pages(int nr_pages, struct page **pages)
>> }
>> EXPORT_SYMBOL(gnttab_free_pages);
>>
>> +int gnttab_dma_alloc_pages(struct device *dev, bool coherent,
>> + int nr_pages, struct page **pages,
>> + void **vaddr, dma_addr_t *dev_bus_addr)
>> +{
>> + int i;
>> + int ret;
>> +
>> + ret = alloc_dma_xenballooned_pages(dev, coherent, nr_pages, pages,
>> + vaddr, dev_bus_addr);
>> + if (ret < 0)
>> + return ret;
>> +
>> + for (i = 0; i < nr_pages; i++) {
>> +#if BITS_PER_LONG < 64
>> + struct xen_page_foreign *foreign;
>> +
>> + foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
>> + if (!foreign) {
>> + gnttab_dma_free_pages(dev, flags, nr_pages, pages,
>> + *vaddr, *dev_bus_addr);
>> + return -ENOMEM;
>> + }
>> + set_page_private(pages[i], (unsigned long)foreign);
>> +#endif
>> + SetPagePrivate(pages[i]);
>> + }
>> + return 0;
>> +}
>> +EXPORT_SYMBOL(gnttab_dma_alloc_pages);
>> +
>> +void gnttab_dma_free_pages(struct device *dev, bool coherent,
>> + int nr_pages, struct page **pages,
>> + void *vaddr, dma_addr_t dev_bus_addr)
>> +{
>> + int i;
>> +
>> + for (i = 0; i < nr_pages; i++) {
>> + if (PagePrivate(pages[i])) {
>> +#if BITS_PER_LONG < 64
>> + kfree((void *)page_private(pages[i]));
>> +#endif
>> + ClearPagePrivate(pages[i]);
>> + }
>> + }
>> + free_dma_xenballooned_pages(dev, coherent, nr_pages, pages,
>> + vaddr, dev_bus_addr);
>> +}
>> +EXPORT_SYMBOL(gnttab_dma_free_pages);
>
> Given that these routines look almost exactly like their non-dma
> counterparts I wonder whether common code could be factored out.
Yes, this can be done
> -boris
>
>
>
>
>> +
>> /* Handling of paged out grant targets (GNTST_eagain) */
>> #define MAX_DELAY 256
>> static inline void
>> diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
>> index 34b1379f9777..20ee2b5ba965 100644
>> --- a/include/xen/grant_table.h
>> +++ b/include/xen/grant_table.h
>> @@ -195,6 +195,13 @@ void gnttab_free_auto_xlat_frames(void);
>> int gnttab_alloc_pages(int nr_pages, struct page **pages);
>> void gnttab_free_pages(int nr_pages, struct page **pages);
>>
>> +int gnttab_dma_alloc_pages(struct device *dev, bool coherent,
>> + int nr_pages, struct page **pages,
>> + void **vaddr, dma_addr_t *dev_bus_addr);
>> +void gnttab_dma_free_pages(struct device *dev, bool coherent,
>> + int nr_pages, struct page **pages,
>> + void *vaddr, dma_addr_t dev_bus_addr);
>> +
>> int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
>> struct gnttab_map_grant_ref *kmap_ops,
>> struct page **pages, unsigned int count);

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