diff mbox

[Xen-devel,v3,2/8] tools: arm: report an error if the guest RAM is too large

Message ID 1398690132-5651-2-git-send-email-ian.campbell@citrix.com
State New
Headers show

Commit Message

Ian Campbell April 28, 2014, 1:02 p.m. UTC 
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>
---
This is the only patch in this series which I consider to be suitable for
backporting to Xen 4.4

v2:
 - Use GUEST_RAM_SIZE instead of GUEST_RAM_END
 - Refactor the ramlimit into one place.
---
 tools/libxc/xc_dom_arm.c      |    9 +++++++++
 xen/include/public/arch-arm.h |    3 ++-
 2 files changed, 11 insertions(+), 1 deletion(-)

Comments

Ian Jackson May 2, 2014, 2:35 p.m. UTC | #1 
Ian Campbell writes ("[PATCH v3 2/8] 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>

Not my area, but:

Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

Ian.
diff mbox

Patch

diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
index 60ac51a..46dfc36 100644
--- 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" > %"PRIx64,
+                  __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 7496556..dd53c94 100644
--- 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