xen: check memory area against e820 map

Provide a service routine to check a physical memory area against the
E820 map. The routine will return false if the complete area is RAM
according to the E820 map and true otherwise.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Acked-by: Konrad Rzeszutek Wilk <Konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

2 files changed, 24 insertions, 0 deletions

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 87251b4c2e30..99ef82cc4edc 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -573,6 +573,29 @@ static unsigned long __init xen_count_remap_pages(unsigned long max_pfn)
         return extra;
 }
 
+bool __init xen_is_e820_reserved(phys_addr_t start, phys_addr_t size)
+{
+        struct e820entry *entry;
+        unsigned mapcnt;
+        phys_addr_t end;
+
+        if (!size)
+                return false;
+
+        end = start + size;
+        entry = xen_e820_map;
+
+        for (mapcnt = 0; mapcnt < xen_e820_map_entries; mapcnt++) {
+                if (entry->type == E820_RAM && entry->addr <= start &&
+                    (entry->addr + entry->size) >= end)
+                        return false;
+
+                entry++;
+        }
+
+        return true;
+}
+
 /*
  * Reserve Xen mfn_list.
  * See comment above "struct start_info" in <xen/interface/xen.h>
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 2292721b1d10..a4cbb76642d8 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -39,6 +39,7 @@ void xen_reserve_top(void);
 void xen_mm_pin_all(void);
 void xen_mm_unpin_all(void);
 
+bool __init xen_is_e820_reserved(phys_addr_t start, phys_addr_t size);
 unsigned long __ref xen_chk_extra_mem(unsigned long pfn);
 void __init xen_inv_extra_mem(void);
 void __init xen_remap_memory(void);