[PATCH v1 3/3] tools/arm: Add the trap_unmapped_mmio xl config option

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

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

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xxxxxxx>
---
 docs/man/xl.cfg.5.pod.in             | 6 ++++++
 tools/golang/xenlight/helpers.gen.go | 3 ++-
 tools/golang/xenlight/types.gen.go   | 1 +
 tools/libs/light/libxl_arm.c         | 8 ++++++--
 tools/libs/light/libxl_types.idl     | 1 +
 tools/xl/xl_parse.c                  | 3 +++
 6 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 7339c44efd..6dd0a05482 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -3089,6 +3089,12 @@ will be used for the domain. Otherwise, the value 
specified by the `nr_spis`
 parameter will be used. The number of SPIs should match the highest interrupt
 ID that will be assigned to the domain.
 
+=item B<trap_unmapped_mmio=BOOLEAN>
+
+An Optional boolean parameter that configures handling of accesses to unmapped
+MMIO ranges. If enabled, guest accesses will trap. If disabled, guest accesses
+will read 0xFFFFFFFF and writes ignored.
+
 =back
 
 =head3 x86
diff --git a/tools/golang/xenlight/helpers.gen.go 
b/tools/golang/xenlight/helpers.gen.go
index 90846ea8e8..b04561929c 100644
--- a/tools/golang/xenlight/helpers.gen.go
+++ b/tools/golang/xenlight/helpers.gen.go
@@ -1163,6 +1163,7 @@ x.ArchArm.GicVersion = GicVersion(xc.arch_arm.gic_version)
 x.ArchArm.Vuart = VuartType(xc.arch_arm.vuart)
 x.ArchArm.SveVl = SveType(xc.arch_arm.sve_vl)
 x.ArchArm.NrSpis = uint32(xc.arch_arm.nr_spis)
+x.ArchArm.TrapUnmappedMmio = uint32(xc.arch_arm.trap_unmapped_mmio)
 if err := x.ArchX86.MsrRelaxed.fromC(&xc.arch_x86.msr_relaxed);err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
@@ -1687,7 +1688,7 @@ return fmt.Errorf("invalid union key '%v'", x.Type)}
 xc.arch_arm.gic_version = C.libxl_gic_version(x.ArchArm.GicVersion)
 xc.arch_arm.vuart = C.libxl_vuart_type(x.ArchArm.Vuart)
 xc.arch_arm.sve_vl = C.libxl_sve_type(x.ArchArm.SveVl)
-xc.arch_arm.nr_spis = C.uint32_t(x.ArchArm.NrSpis)
+xc.arch_arm.trap_unmapped_mmio = C.uint32_t(x.ArchArm.TrapUnmappedMmio)
 if err := x.ArchX86.MsrRelaxed.toC(&xc.arch_x86.msr_relaxed); err != nil {
 return fmt.Errorf("converting field ArchX86.MsrRelaxed: %v", err)
 }
diff --git a/tools/golang/xenlight/types.gen.go 
b/tools/golang/xenlight/types.gen.go
index e7667f1ce3..89cc976bdc 100644
--- a/tools/golang/xenlight/types.gen.go
+++ b/tools/golang/xenlight/types.gen.go
@@ -599,6 +599,7 @@ GicVersion GicVersion
 Vuart VuartType
 SveVl SveType
 NrSpis uint32
+TrapUnmappedMmio Defbool
 }
 ArchX86 struct {
 MsrRelaxed Defbool
diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 40cd005619..cce3fc4684 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -233,8 +233,9 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
         config->arch.sve_vl = d_config->b_info.arch_arm.sve_vl / 128U;
     }
 
-    /* Trap accesses to unmapped MMIO. */
-    config->arch.flags = XEN_ARM_TRAP_UNMAPPED_MMIO;
+    config->arch.flags = 0;
+    if (libxl_defbool_val(d_config->b_info.arch_arm.trap_unmapped_mmio))
+        config->arch.flags |= XEN_ARM_TRAP_UNMAPPED_MMIO;
 
     return 0;
 }
@@ -1714,6 +1715,9 @@ int libxl__arch_domain_build_info_setdefault(libxl__gc 
*gc,
     /* ACPI is disabled by default */
     libxl_defbool_setdefault(&b_info->acpi, false);
 
+    /* Trapping of unmapped MMIO access enabled by default.  */
+    libxl_defbool_setdefault(&b_info->arch_arm.trap_unmapped_mmio, true);
+
     /* Sanitise SVE parameter */
     if (b_info->arch_arm.sve_vl) {
         unsigned int max_sve_vl =
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index 9bb2969931..bd5425fe50 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -724,6 +724,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                ("vuart", libxl_vuart_type),
                                ("sve_vl", libxl_sve_type),
                                ("nr_spis", uint32, {'init_val': 
'LIBXL_NR_SPIS_DEFAULT'}),
+                               ("trap_unmapped_mmio", libxl_defbool),
                               ])),
     ("arch_x86", Struct(None, [("msr_relaxed", libxl_defbool),
                               ])),
diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
index 089a88935a..3099086198 100644
--- a/tools/xl/xl_parse.c
+++ b/tools/xl/xl_parse.c
@@ -2975,6 +2975,9 @@ skip_usbdev:
     if (!xlu_cfg_get_long (config, "nr_spis", &l, 0))
         b_info->arch_arm.nr_spis = l;
 
+    xlu_cfg_get_defbool(config, "trap_unmapped_mmio",
+                        &b_info->arch_arm.trap_unmapped_mmio, 0);
+
     parse_vkb_list(config, d_config);
 
     d_config->virtios = NULL;
-- 
2.43.0