[xen staging] tools/arm: Reject configuration with incorrect nr_spis value

[patchbot@xxxxxxx]

commit 55d62b8d4636e22290e1d93704ab0b85a8c1a860
Author:     Michal Orzel <michal.orzel@xxxxxxx>
AuthorDate: Wed Mar 12 11:16:19 2025 +0100
Commit:     Michal Orzel <michal.orzel@xxxxxxx>
CommitDate: Thu Mar 13 08:10:48 2025 +0100

    tools/arm: Reject configuration with incorrect nr_spis value
    
    If the calculated value for nr_spis by the toolstack is bigger than the
    value provided by the user, we silently ignore the latter. This is not
    consistent with the approach we have in Xen on Arm when we try to reject
    incorrect configuration. Also, the documentation for nr_spis is
    incorrect as it mentions 991 as the number of max SPIs, where it should
    be 960 i.e. (1020 - 32) rounded down to the nearest multiple of 32.
    
    Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
    Reviewed-by: Bertrand Marquis <bertrand.marquis@xxxxxxx>
---
 docs/man/xl.cfg.5.pod.in     | 13 +++++--------
 tools/libs/light/libxl_arm.c |  6 ++++++
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
index 8e1422104e..7339c44efd 100644
--- a/docs/man/xl.cfg.5.pod.in
+++ b/docs/man/xl.cfg.5.pod.in
@@ -3083,14 +3083,11 @@ interval of colors (such as "0-4").
 =item B<nr_spis="NR_SPIS">
 
 An optional integer parameter specifying the number of SPIs (Shared
-Peripheral Interrupts) to allocate for the domain. Max is 991 SPIs. If
-the value specified by the `nr_spis` parameter is smaller than the
-number of SPIs calculated by the toolstack based on the devices
-allocated for the domain, or the `nr_spis` parameter is not specified,
-the value calculated by the toolstack 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.
+Peripheral Interrupts) to allocate for the domain. Max is 960 SPIs. If
+the `nr_spis` parameter is not specified, the value calculated by the toolstack
+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.
 
 =back
 
diff --git a/tools/libs/light/libxl_arm.c b/tools/libs/light/libxl_arm.c
index 5a9db5e85f..2d895408ca 100644
--- a/tools/libs/light/libxl_arm.c
+++ b/tools/libs/light/libxl_arm.c
@@ -181,6 +181,12 @@ 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) {
+        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);
     LOG(DEBUG, " - Allocate %u SPIs", config->arch.nr_spis);
 
--
generated by git-patchbot for /home/xen/git/xen.git#staging