[PATCH] tools/arm: Fix nr_spis handling v2

[Michal Orzel <michal.orzel@xxxxxxx>]

We are missing a way to detect whether a user provided a value for
nr_spis equal to 0 or did not provide any value (default is also 0) which
can cause issues when calculated nr_spis is > 0 and the value from domain
config is 0. Fix it by setting default value for nr_spis to UINT32_MAX
(max supported nr of SPIs is 960 anyway).

Fixes: 55d62b8d4636 ("tools/arm: Reject configuration with incorrect nr_spis 
value")
Reported-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
---
 tools/libs/light/libxl_arm.c     | 7 ++++---
 tools/libs/light/libxl_types.idl | 2 +-
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 2d895408cac3..5bb5bac61def 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -84,7 +84,7 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
                                       libxl_domain_config *d_config,
                                       struct xen_domctl_createdomain *config)
 {
-    uint32_t nr_spis = 0;
+    uint32_t nr_spis = 0, cfg_nr_spis = d_config->b_info.arch_arm.nr_spis;
     unsigned int i;
     uint32_t vuart_irq, virtio_irq = 0;
     bool vuart_enabled = false, virtio_enabled = false;
@@ -181,13 +181,14 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
 
     LOG(DEBUG, "Configure the domain");
 
-    if (nr_spis > d_config->b_info.arch_arm.nr_spis) {
+    /* We use UINT32_MAX to denote if a user provided a value or not */
+    if ((cfg_nr_spis != UINT32_MAX) && (nr_spis > cfg_nr_spis)) {
         LOG(ERROR, "Provided nr_spis value is too small (minimum required 
%u)\n",
             nr_spis);
         return ERROR_FAIL;
     }
 
-    config->arch.nr_spis = max(nr_spis, d_config->b_info.arch_arm.nr_spis);
+    config->arch.nr_spis = (cfg_nr_spis != UINT32_MAX) ? cfg_nr_spis : nr_spis;
     LOG(DEBUG, " - Allocate %u SPIs", config->arch.nr_spis);
 
     switch (d_config->b_info.arch_arm.gic_version) {
diff --git a/tools/libs/light/libxl_types.idl b/tools/libs/light/libxl_types.idl
index bd4b8721ff19..129c00ce929c 100644
--- a/tools/libs/light/libxl_types.idl
+++ b/tools/libs/light/libxl_types.idl
@@ -723,7 +723,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
     ("arch_arm", Struct(None, [("gic_version", libxl_gic_version),
                                ("vuart", libxl_vuart_type),
                                ("sve_vl", libxl_sve_type),
-                               ("nr_spis", uint32),
+                               ("nr_spis", uint32, {'init_val': 'UINT32_MAX'}),
                               ])),
     ("arch_x86", Struct(None, [("msr_relaxed", libxl_defbool),
                               ])),
-- 
2.25.1