xen/swiotlb: remember having called xen_create_contiguous_region()

Instead of always calling xen_destroy_contiguous_region() in case the
memory is DMA-able for the used device, do so only in case it has been
made DMA-able via xen_create_contiguous_region() before.

This will avoid a lot of xen_destroy_contiguous_region() calls for
64-bit capable devices.

As the memory in question is owned by swiotlb-xen the PG_owner_priv_1
flag of the first allocated page can be used for remembering.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
index 37ddcfcfbb213c468e432f0e05d49bcb0fc475d1..ceb681cf64bb11beeb4cea92462a46dcb1dfe3ef 100644 (file)
--- a/drivers/xen/swiotlb-xen.c
+++ b/drivers/xen/swiotlb-xen.c
@@ -322,6 +322,7 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
                        xen_free_coherent_pages(hwdev, size, ret, (dma_addr_t)phys, attrs);
                        return NULL;
                }
+               SetPageXenRemapped(virt_to_page(ret));
        }
        memset(ret, 0, size);
        return ret;
@@ -346,7 +347,8 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
        size = 1UL << (order + XEN_PAGE_SHIFT);
 
        if (!WARN_ON((dev_addr + size - 1 > dma_mask) ||
-                    range_straddles_page_boundary(phys, size)))
+                    range_straddles_page_boundary(phys, size)) &&
+           TestClearPageXenRemapped(virt_to_page(vaddr)))
                xen_destroy_contiguous_region(phys, order);
 
        xen_free_coherent_pages(hwdev, size, vaddr, (dma_addr_t)phys, attrs);

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index b848517da64c3945e4f0bfe2fc6210ce801f165b..f91cb8898ff0af60d751f7c026c7b9f852fe620b 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -152,6 +152,8 @@ enum pageflags {
        PG_savepinned = PG_dirty,
        /* Has a grant mapping of another (foreign) domain's page. */
        PG_foreign = PG_owner_priv_1,
+       /* Remapped by swiotlb-xen. */
+       PG_xen_remapped = PG_owner_priv_1,
 
        /* SLOB */
        PG_slob_free = PG_private,
@@ -329,6 +331,8 @@ PAGEFLAG(Pinned, pinned, PF_NO_COMPOUND)
        TESTSCFLAG(Pinned, pinned, PF_NO_COMPOUND)
 PAGEFLAG(SavePinned, savepinned, PF_NO_COMPOUND);
 PAGEFLAG(Foreign, foreign, PF_NO_COMPOUND);
+PAGEFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
+       TESTCLEARFLAG(XenRemapped, xen_remapped, PF_NO_COMPOUND)
 
 PAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)
        __CLEARPAGEFLAG(Reserved, reserved, PF_NO_COMPOUND)