Re: [Xen-devel] [PATCH RFC 0/2] Fix PAGE_SIZE issues in public headers

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 19 Oct 2016, Stefano Stabellini wrote:
> On Wed, 19 Oct 2016, Juergen Gross wrote:
> > On 19/10/16 12:46, Wei Liu wrote:
> > > Reference to PAGE_SIZE slipped in to two public header files. QEMU build 
> > > on
> > > ARM64 is broken by this.
> > > 
> > > This series tries to fix that. The approach is discussed at [0].
> > > 
> > > QEMU will need to update its copy of usbif.h.
> > 
> > There is no QEMU copy of Xen headers. This is the reason why an
> > imcompatible change is not possible. With the patches there is no
> > longer an urgent need for qemu to be modified.
> 
> Yes, as long as we backport the fixes to the Xen stable trees as soon as
> possible.

I spoke too soon. Actually QEMU xen-usb.c references PAGE_SIZE
directly, which also needs to be fixed. In this case, I think I would
use XC_PAGE_SIZE, because we are already using it in that file and
because this way we don't tie the fix with the public headers fixes in
Xen.

---

xen-usb: do not reference PAGE_SIZE

PAGE_SIZE is undefined on ARM64. Use XC_PAGE_SIZE instead, which is
always 4096 even when page granularity is 64K.

For this to actually work with 64K pages, more changes are required.

Signed-off-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

diff --git a/hw/usb/xen-usb.c b/hw/usb/xen-usb.c
index 174d715..de2ebd6 100644
--- a/hw/usb/xen-usb.c
+++ b/hw/usb/xen-usb.c
@@ -160,7 +160,7 @@ static int usbback_gnttab_map(struct usbback_req 
*usbback_req)
 
     for (i = 0; i < nr_segs; i++) {
         if ((unsigned)usbback_req->req.seg[i].offset +
-            (unsigned)usbback_req->req.seg[i].length > PAGE_SIZE) {
+            (unsigned)usbback_req->req.seg[i].length > XC_PAGE_SIZE) {
             xen_be_printf(xendev, 0, "segment crosses page boundary\n");
             return -EINVAL;
         }
@@ -183,7 +183,7 @@ static int usbback_gnttab_map(struct usbback_req 
*usbback_req)
 
         for (i = 0; i < usbback_req->nr_buffer_segs; i++) {
             seg = usbback_req->req.seg + i;
-            addr = usbback_req->buffer + i * PAGE_SIZE + seg->offset;
+            addr = usbback_req->buffer + i * XC_PAGE_SIZE + seg->offset;
             qemu_iovec_add(&usbback_req->packet.iov, addr, seg->length);
         }
     }


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