[PATCH v3 2/5] xen/arm: dom0less: Add trap-unmapped-accesses

["Edgar E. Iglesias" <edgar.iglesias@xxxxxxxxx>]

From: "Edgar E. Iglesias" <edgar.iglesias@xxxxxxx>

Add the trap-unmapped-accesses per-domain fdt property.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
---
 docs/misc/arm/device-tree/booting.txt | 10 ++++++++++
 xen/arch/arm/dom0less-build.c         |  9 ++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index 59fa96a82e..9add6440de 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -225,6 +225,16 @@ with the following properties:
     option is provided with a non zero value, but the platform doesn't support
     SVE.
 
+- trap-unmapped-accesses
+
+    Optional. An integer that configures handling of accesses to unmapped
+    address ranges.
+    If set to 0, guest accesses will read all bits as ones, e.g 0xFFFFFFFF
+    for a 32bit access and writes will be ignored.
+    If set to 1, guest accesses will trap.
+
+    This option is only implemented for ARM where the default is 1.
+
 - xen,enhanced
 
     A string property. Possible property values are:
diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
index a4e0a33632..69324aa597 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -344,8 +344,15 @@ void __init arch_create_domUs(struct dt_device_node *node,
 #endif
     }
 
-    /* Trap accesses to unmapped areas. */
+    /* Trap unmapped accesses by default. */
     d_cfg->flags |= XEN_DOMCTL_CDF_trap_unmapped_accesses;
+    if ( dt_property_read_u32(node, "trap-unmapped-accesses", &val) )
+    {
+        if ( val > 1 )
+            panic("trap-unmapped-accesses: supported values are 0 or 1");
+        if ( !val )
+            d_cfg->flags &= ~XEN_DOMCTL_CDF_trap_unmapped_accesses;
+    }
 }
 
 int __init init_intc_phandle(struct kernel_info *kinfo, const char *name,
-- 
2.43.0