Hi Edgar,
On 29/05/2025 16:50, Edgar E. Iglesias wrote:
From: "Edgar E. Iglesias" <edgar.igles...@amd.com>
Add the trap-unmapped-accesses per-domain fdt property.
Signed-off-by: Edgar E. Iglesias <edgar.igles...@amd.com>
---
docs/misc/arm/device-tree/booting.txt | 9 +++++++++
xen/arch/arm/dom0less-build.c | 9 ++++++++-
2 files changed, 17 insertions(+), 1 deletion(-)
diff --git a/docs/misc/arm/device-tree/booting.txt
b/docs/misc/arm/device-tree/booting.txt
index 59fa96a82e..8a5c40ddf3 100644
--- a/docs/misc/arm/device-tree/booting.txt
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -225,6 +225,15 @@ 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 0xFFFFFFFF and writes will be
ignored.
Looking at the code, if I am not mistaken, it will only return this
value for 32-bit. For 64-bit there will be a few Fs more and for less
there will be less. So I think this needs to be reworded.
The rest looks good to me.
+
+ 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,
Cheers,
--
Julien Grall
