From 875553e317b28e66824fec73ad4459372576ec68 Mon Sep 17 00:00:00 2001 From: Oleksandr Tyshchenko Date: Sat, 8 Oct 2022 18:10:12 +0300 Subject: xen/virtio: Handle cases when page offset > PAGE_SIZE properly Passed to xen_grant_dma_map_page() offset in the page can be > PAGE_SIZE even if the guest uses the same page granularity as Xen (4KB). Before current patch, if such case happened we ended up providing grants for the whole region in xen_grant_dma_map_page() which was really unnecessary. The more, we ended up not releasing all grants which represented that region in xen_grant_dma_unmap_page(). Current patch updates the code to be able to deal with such cases. Signed-off-by: Oleksandr Tyshchenko Reviewed-by: Stefano Stabellini Reviewed-by: Xenia Ragiadakou Link: https://lore.kernel.org/r/20221008151013.2537826-2-olekstysh@gmail.com Signed-off-by: Juergen Gross --- drivers/xen/grant-dma-ops.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers/xen') diff --git a/drivers/xen/grant-dma-ops.c b/drivers/xen/grant-dma-ops.c index 860f37c93af4..3089940436be 100644 --- a/drivers/xen/grant-dma-ops.c +++ b/drivers/xen/grant-dma-ops.c @@ -168,7 +168,9 @@ static dma_addr_t xen_grant_dma_map_page(struct device *dev, struct page *page, unsigned long attrs) { struct xen_grant_dma_data *data; - unsigned int i, n_pages = PFN_UP(offset + size); + unsigned long dma_offset = offset_in_page(offset), + pfn_offset = PFN_DOWN(offset); + unsigned int i, n_pages = PFN_UP(dma_offset + size); grant_ref_t grant; dma_addr_t dma_handle; @@ -187,10 +189,11 @@ static dma_addr_t xen_grant_dma_map_page(struct device *dev, struct page *page, for (i = 0; i < n_pages; i++) { gnttab_grant_foreign_access_ref(grant + i, data->backend_domid, - xen_page_to_gfn(page) + i, dir == DMA_TO_DEVICE); + pfn_to_gfn(page_to_xen_pfn(page) + i + pfn_offset), + dir == DMA_TO_DEVICE); } - dma_handle = grant_to_dma(grant) + offset; + dma_handle = grant_to_dma(grant) + dma_offset; return dma_handle; } -- cgit v1.2.3