[RFC PATCH 2/5] hw/arm/virt: Add cpu-map to device tree

[Ying Fang]

Support device tree CPU topology descriptions.

Signed-off-by: Ying Fang <fangying1@huawei.com>
---
 hw/arm/virt.c         | 38 +++++++++++++++++++++++++++++++++++++-
 include/hw/arm/virt.h |  1 +
 2 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 371147f3ae..c133b342b8 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -351,10 +351,11 @@ static void fdt_add_cpu_nodes(const VirtMachineState *vms)
     int cpu;
     int addr_cells = 1;
     const MachineState *ms = MACHINE(vms);
+    const VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms);
     int smp_cpus = ms->smp.cpus;
 
     /*
-     * From Documentation/devicetree/bindings/arm/cpus.txt
+     * See Linux Documentation/devicetree/bindings/arm/cpus.yaml
      *  On ARM v8 64-bit systems value should be set to 2,
      *  that corresponds to the MPIDR_EL1 register size.
      *  If MPIDR_EL1[63:32] value is equal to 0 on all CPUs
@@ -407,8 +408,42 @@ static void fdt_add_cpu_nodes(const VirtMachineState *vms)
                 ms->possible_cpus->cpus[cs->cpu_index].props.node_id);
         }
 
+        if (ms->smp.cpus > 1 && !vmc->no_cpu_topology) {
+            qemu_fdt_setprop_cell(vms->fdt, nodename, "phandle",
+                                  qemu_fdt_alloc_phandle(vms->fdt));
+        }
+
         g_free(nodename);
     }
+
+    if (ms->smp.cpus > 1 && !vmc->no_cpu_topology) {
+        /*
+         * See Linux Documentation/devicetree/bindings/cpu/cpu-topology.txt
+         */
+        qemu_fdt_add_subnode(vms->fdt, "/cpus/cpu-map");
+
+        for (cpu = ms->smp.cpus - 1; cpu >= 0; cpu--) {
+            char *cpu_path = g_strdup_printf("/cpus/cpu@%d", cpu);
+            char *map_path;
+
+            if (ms->smp.threads > 1) {
+                map_path = g_strdup_printf(
+                            "/cpus/cpu-map/%s%d/%s%d/%s%d",
+                            "cluster", cpu / (ms->smp.cores * ms->smp.threads),
+                            "core", (cpu / ms->smp.threads) % ms->smp.cores,
+                            "thread", cpu % ms->smp.threads);
+            } else {
+                map_path = g_strdup_printf(
+                            "/cpus/cpu-map/%s%d/%s%d",
+                            "cluster", cpu / ms->smp.cores,
+                            "core", cpu % ms->smp.cores);
+            }
+            qemu_fdt_add_path(vms->fdt, map_path);
+            qemu_fdt_setprop_phandle(vms->fdt, map_path, "cpu", cpu_path);
+            g_free(map_path);
+            g_free(cpu_path);
+        }
+    }
 }
 
 static void fdt_add_its_gic_node(VirtMachineState *vms)
@@ -2742,6 +2777,7 @@ static void virt_machine_5_2_options(MachineClass *mc)
     virt_machine_6_0_options(mc);
     compat_props_add(mc->compat_props, hw_compat_5_2, hw_compat_5_2_len);
     vmc->no_secure_gpio = true;
+    vmc->no_cpu_topology = true;
 }
 DEFINE_VIRT_MACHINE(5, 2)
 
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index ee9a93101e..7ef6d08ac3 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -129,6 +129,7 @@ struct VirtMachineClass {
     bool no_kvm_steal_time;
     bool acpi_expose_flash;
     bool no_secure_gpio;
+    bool no_cpu_topology;
 };
 
 struct VirtMachineState {
-- 
2.23.0