[PATCH v1 2/3] xen/arm: dom0less: Add trap-unmapped-mmio-disabled

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

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

Add the trap-unmapped-mmio-disabled per-domain fdt property.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
---
 docs/misc/arm/device-tree/booting.txt | 7 +++++++
 xen/arch/arm/dom0less-build.c         | 3 ++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
index 59fa96a82e..75fbb245d1 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -225,6 +225,13 @@ with the following properties:
     option is provided with a non zero value, but the platform doesn't support
     SVE.
 
+- trap-unmapped-mmio-disabled
+
+    Optional. A boolean property that configures handling of accesses to
+    unmapped MMIO ranges.
+    If set, guest accesses will read 0xFFFFFFFF and writes ignored.
+    If not set, guest accesses will trap.
+
 - 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 e5e13e07d0..cd1ef05d89 100644
--- a/xen/arch/arm/dom0less-build.c
+++ b/xen/arch/arm/dom0less-build.c
@@ -344,8 +344,9 @@ void __init arch_create_domUs(struct dt_device_node *node,
 #endif
     }
 
-    /* Trap accesses to unmapped MMIO. */
     d_cfg->arch.flags = XEN_ARM_TRAP_UNMAPPED_MMIO;
+    if ( dt_property_read_bool(node, "trap-unmapped-mmio-disabled") )
+        d_cfg->arch.flags &= ~XEN_ARM_TRAP_UNMAPPED_MMIO;
 }
 
 int __init init_intc_phandle(struct kernel_info *kinfo, const char *name,
-- 
2.43.0