[PATCH] xen/arm: Correctly implement domain_page_map_to_mfn

[Julien Grall <julien.grall@linaro.org>]

The function domain_page_map_to_mfn can be used to translate a virtual
address mapped by both map_domain_page and map_domain_page_global.
The former is using vmap to map the mfn, therefore domain_page_map_to_mfn
will always fail because the address is not in DOMHEAP range.

Check if the address is in vmap range and use __pa to translate it.

This patch fix guest shutdown when the event fifo is used.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Cc: George Dunlap <george.dunlap@citrix.com>

---
    This is a bug fix for Xen 4.4. Without this patch, it's impossible to
use Linux 3.14 (and higher) as guest with the event fifo driver.
---
 xen/arch/arm/mm.c |   10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 127cce0..bdca68a 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -325,11 +325,15 @@ void unmap_domain_page(const void *va)
     local_irq_restore(flags);
 }
 
-unsigned long domain_page_map_to_mfn(const void *va)
+unsigned long domain_page_map_to_mfn(const void *ptr)
 {
+    unsigned long va = (unsigned long)ptr;
     lpae_t *map = this_cpu(xen_dommap);
-    int slot = ((unsigned long) va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
-    unsigned long offset = ((unsigned long)va>>THIRD_SHIFT) & LPAE_ENTRY_MASK;
+    int slot = (va - DOMHEAP_VIRT_START) >> SECOND_SHIFT;
+    unsigned long offset = (va>>THIRD_SHIFT) & LPAE_ENTRY_MASK;
+
+    if ( va >= VMAP_VIRT_START && va < VMAP_VIRT_END )
+        return virt_to_mfn(va);
 
     ASSERT(slot >= 0 && slot < DOMHEAP_ENTRIES);
     ASSERT(map[slot].pt.avail != 0);
-- 
1.7.10.4