From: Clément Chigot <chigot@adacore.com>

Currently, arm booting processus assumes that the first_cpu is the CPU
that will boot: `arm_load_kernel` is powering off all but the `first_cpu`;
`do_cpu_reset` is setting the loader address only for this `first_cpu`.

For most of the boards, this isn't an issue as the kernel is loaded and
booted on the first CPU anyway. However, for zynqmp, the option
"boot-cpu" allows to choose any CPUs.

Create a new arm_boot_info entry `primary_cpu` recording which CPU will
be boot first. This one is set when `arm_boot_kernel` is called.

Signed-off-by: Clément Chigot <chigot@adacore.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20250526085523.809003-2-chigot@adacore.com
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 include/hw/arm/boot.h |  3 +++
 hw/arm/boot.c         | 15 +++++++--------
 2 files changed, 10 insertions(+), 8 deletions(-)

diff --git a/include/hw/arm/boot.h b/include/hw/arm/boot.h
index b12bf61ca81..a2e22bda8a5 100644
--- a/include/hw/arm/boot.h
+++ b/include/hw/arm/boot.h
@@ -132,6 +132,9 @@ struct arm_boot_info {
     bool secure_board_setup;
 
     arm_endianness endianness;
+
+    /* CPU having load the kernel and that should be the first to boot.  */
+    ARMCPU *primary_cpu;
 };
 
 /**
diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 79afb51b8a5..3c93d879857 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -744,7 +744,7 @@ static void do_cpu_reset(void *opaque)
             } else {
                 if (arm_feature(env, ARM_FEATURE_EL3) &&
                     (info->secure_boot ||
-                     (info->secure_board_setup && cs == first_cpu))) {
+                     (info->secure_board_setup && cpu == info->primary_cpu))) {
                     /* Start this CPU in Secure SVC */
                     target_el = 3;
                 }
@@ -752,7 +752,7 @@ static void do_cpu_reset(void *opaque)
 
             arm_emulate_firmware_reset(cs, target_el);
 
-            if (cs == first_cpu) {
+            if (cpu == info->primary_cpu) {
                 AddressSpace *as = arm_boot_address_space(cpu, info);
 
                 cpu_set_pc(cs, info->loader_start);
@@ -1239,6 +1239,9 @@ void arm_load_kernel(ARMCPU *cpu, MachineState *ms, struct arm_boot_info *info)
     info->dtb_filename = ms->dtb;
     info->dtb_limit = 0;
 
+    /* We assume the CPU passed as argument is the primary CPU.  */
+    info->primary_cpu = cpu;
+
     /* Load the kernel.  */
     if (!info->kernel_filename || info->firmware_loaded) {
         arm_setup_firmware_boot(cpu, info);
@@ -1288,12 +1291,8 @@ void arm_load_kernel(ARMCPU *cpu, MachineState *ms, struct arm_boot_info *info)
 
             object_property_set_int(cpuobj, "psci-conduit", info->psci_conduit,
                                     &error_abort);
-            /*
-             * Secondary CPUs start in PSCI powered-down state. Like the
-             * code in do_cpu_reset(), we assume first_cpu is the primary
-             * CPU.
-             */
-            if (cs != first_cpu) {
+            /* Secondary CPUs start in PSCI powered-down state.  */
+            if (ARM_CPU(cs) != info->primary_cpu) {
                 object_property_set_bool(cpuobj, "start-powered-off", true,
                                          &error_abort);
             }
-- 
2.43.0