[Xen-devel] [PATCH] evtchn/fifo: map correct pages when guest is HVM

[David Vrabel <david.vrabel@xxxxxxxxxx>]

From: David Vrabel <david.vrabel@xxxxxxxxxx>

If a HVM guest attempts to use the FIFO-based ABI it will not receive
any events and destroying the guest may crash Xen or trigger an assert
when attempting to unmap a control block page.  This occurs because
Xen maps the wrong page for both the control blocks and the event
arrays.

In map_guest_page(), use the MFN of the guest's page and not the GFN
when calling map_domain_page_global().

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---
 xen/common/event_fifo.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/xen/common/event_fifo.c b/xen/common/event_fifo.c
index fc43e62..a815b2d 100644
--- a/xen/common/event_fifo.c
+++ b/xen/common/event_fifo.c
@@ -357,7 +357,7 @@ static int map_guest_page(struct domain *d, uint64_t gfn, 
void **virt)
         return -EINVAL;
     }
 
-    *virt = map_domain_page_global(gfn);
+    *virt = map_domain_page_global(page_to_mfn(p));
     if ( !*virt )
     {
         put_page_and_type(p);
-- 
1.7.2.5


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