tools: arm: report an error if the guest RAM is too large

Due to the layout of the guest physical address space we cannot support more
than 768M of RAM before overrunning the area set aside for the grant table. Due
to the presence of the magic pages at the end of the RAM region guests are
actually limited to 767M.

Catch this case during domain build and fail gracefully instead of obscurely
later on.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
index 60ac51ad9d5d98c026f98cfb4a8a06bbdb596129..d5831a219caebdbd61ab2d424c663adc45beb799 100644 (file)
--- a/tools/libxc/xc_dom_arm.c
+++ b/tools/libxc/xc_dom_arm.c
@@ -272,6 +272,15 @@ int arch_setup_meminit(struct xc_dom_image *dom)
         return -1;
     }
 
+    if ( ramsize > GUEST_RAM_SIZE - NR_MAGIC_PAGES*XC_PAGE_SIZE )
+    {
+        DOMPRINTF("%s: ram size is too large for guest address space: "
+                  "%"PRIx64" > %llx",
+                  __FUNCTION__, ramsize,
+                  GUEST_RAM_SIZE - NR_MAGIC_PAGES*XC_PAGE_SIZE);
+        return -1;
+    }
+
     rc = set_mode(dom->xch, dom->guest_domid, dom->guest_type);
     if ( rc )
         return rc;

diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 74965560f9d34ccd33e6ea60308cc66adceb3b3e..dd53c9402860873ea637b846e6138014cc417a4a 100644 (file)
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -369,7 +369,8 @@ typedef uint64_t xen_callback_t;
 #define GUEST_GICC_BASE   0x2c002000ULL
 #define GUEST_GICC_SIZE   0x100ULL
 
-#define GUEST_RAM_BASE    0x80000000ULL
+#define GUEST_RAM_BASE    0x80000000ULL /* 768M @ 2GB */
+#define GUEST_RAM_SIZE    0x30000000ULL
 
 #define GUEST_GNTTAB_BASE 0xb0000000ULL
 #define GUEST_GNTTAB_SIZE 0x00020000ULL