[PATCH AUTOSEL 4.9 6/6] xen/xenbus: Fix granting of vmalloc'd memory

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Simon Leiner <simon@xxxxxxxxx>

[ Upstream commit d742db70033c745e410523e00522ee0cfe2aa416 ]

On some architectures (like ARM), virt_to_gfn cannot be used for
vmalloc'd memory because of its reliance on virt_to_phys. This patch
introduces a check for vmalloc'd addresses and obtains the PFN using
vmalloc_to_pfn in that case.

Signed-off-by: Simon Leiner <simon@xxxxxxxxx>
Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200825093153.35500-1-simon@xxxxxxxxx
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/xen/xenbus/xenbus_client.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c 
b/drivers/xen/xenbus/xenbus_client.c
index df27cefb2fa35..266f446ba331c 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -384,8 +384,14 @@ int xenbus_grant_ring(struct xenbus_device *dev, void 
*vaddr,
        int i, j;
 
        for (i = 0; i < nr_pages; i++) {
-               err = gnttab_grant_foreign_access(dev->otherend_id,
-                                                 virt_to_gfn(vaddr), 0);
+               unsigned long gfn;
+
+               if (is_vmalloc_addr(vaddr))
+                       gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr));
+               else
+                       gfn = virt_to_gfn(vaddr);
+
+               err = gnttab_grant_foreign_access(dev->otherend_id, gfn, 0);
                if (err < 0) {
                        xenbus_dev_fatal(dev, err,
                                         "granting access to ring page");
-- 
2.25.1