From: Leif Lindholm <leif@nuviainc.com>

The sbsa-ref platform uses a minimal device tree to pass amount of memory
as well as number of cpus to the firmware. However, when dumping that
minimal dtb (with -M sbsa-virt,dumpdtb=<file>), the resulting blob
generates a warning when decompiled by dtc due to lack of reg property.

Add a simple reg property per cpu, representing a 64-bit MPIDR_EL1.

This also ends up being cleaner than having the firmware calculating its
own IDs for generating APCI.

Signed-off-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20200827124335.30586-1-leif@nuviainc.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/sbsa-ref.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/hw/arm/sbsa-ref.c b/hw/arm/sbsa-ref.c
index 2a7d9a61fc7..7475aac0dfa 100644
--- a/hw/arm/sbsa-ref.c
+++ b/hw/arm/sbsa-ref.c
@@ -138,6 +138,12 @@ static const int sbsa_ref_irqmap[] = {
     [SBSA_EHCI] = 11,
 };
 
+static uint64_t sbsa_ref_cpu_mp_affinity(SBSAMachineState *sms, int idx)
+{
+    uint8_t clustersz = ARM_DEFAULT_CPUS_PER_CLUSTER;
+    return arm_cpu_mp_affinity(idx, clustersz);
+}
+
 /*
  * Firmware on this machine only uses ACPI table to load OS, these limited
  * device tree nodes are just to let firmware know the info which varies from
@@ -183,14 +189,31 @@ static void create_fdt(SBSAMachineState *sms)
         g_free(matrix);
     }
 
+    /*
+     * From Documentation/devicetree/bindings/arm/cpus.yaml
+     *  On ARM v8 64-bit systems this property is required
+     *    and matches the MPIDR_EL1 register affinity bits.
+     *
+     *    * If cpus node's #address-cells property is set to 2
+     *
+     *      The first reg cell bits [7:0] must be set to
+     *      bits [39:32] of MPIDR_EL1.
+     *
+     *      The second reg cell bits [23:0] must be set to
+     *      bits [23:0] of MPIDR_EL1.
+     */
     qemu_fdt_add_subnode(sms->fdt, "/cpus");
+    qemu_fdt_setprop_cell(sms->fdt, "/cpus", "#address-cells", 2);
+    qemu_fdt_setprop_cell(sms->fdt, "/cpus", "#size-cells", 0x0);
 
     for (cpu = sms->smp_cpus - 1; cpu >= 0; cpu--) {
         char *nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
         ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(cpu));
         CPUState *cs = CPU(armcpu);
+        uint64_t mpidr = sbsa_ref_cpu_mp_affinity(sms, cpu);
 
         qemu_fdt_add_subnode(sms->fdt, nodename);
+        qemu_fdt_setprop_u64(sms->fdt, nodename, "reg", mpidr);
 
         if (ms->possible_cpus->cpus[cs->cpu_index].props.has_node_id) {
             qemu_fdt_setprop_cell(sms->fdt, nodename, "numa-node-id",
@@ -717,12 +740,6 @@ static void sbsa_ref_init(MachineState *machine)
     arm_load_kernel(ARM_CPU(first_cpu), machine, &sms->bootinfo);
 }
 
-static uint64_t sbsa_ref_cpu_mp_affinity(SBSAMachineState *sms, int idx)
-{
-    uint8_t clustersz = ARM_DEFAULT_CPUS_PER_CLUSTER;
-    return arm_cpu_mp_affinity(idx, clustersz);
-}
-
 static const CPUArchIdList *sbsa_ref_possible_cpu_arch_ids(MachineState *ms)
 {
     unsigned int max_cpus = ms->smp.max_cpus;
-- 
2.20.1