Unverified Commit 28a4df97 authored by Atish Patra's avatar Atish Patra Committed by Palmer Dabbelt
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riscv: virt: Add cpu-topology DT node. 

Currently, there is no cpu topology defined in RISC-V.
Define a device tree node that clearly describes the
entire topology. This saves the trouble of scanning individual
cache to figure out the topology.

Here is the linux kernel patch series that enables topology
for RISC-V.

http://lists.infradead.org/pipermail/linux-riscv/2019-June/005072.html



CPU topology after applying this patch in QEMU & above series in kernel

/ # cat /sys/devices/system/cpu/cpu2/topology/thread_siblings_list
2
/ # cat /sys/devices/system/cpu/cpu2/topology/physical_package_id
0
/ # cat /sys/devices/system/cpu/cpu2/topology/core_siblings_list
0-7

Signed-off-by: default avatarAtish Patra <atish.patra@wdc.com>
Reviewed-by: default avatarAlistair Francis <alistair.francis@wdc.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent ab433ccc

hw/riscv/virt.c

+20 −2
Original line number Diff line number Diff line
@@ -191,6 +191,7 @@ static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap, 


    for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {

        int cpu_phandle = phandle++;

        int intc_phandle;

        nodename = g_strdup_printf("/cpus/cpu@%d", cpu);

        char *intc = g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);

        char *isa = riscv_isa_string(&s->soc.harts[cpu]);
@@ -203,9 +204,12 @@ static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap, 
        qemu_fdt_setprop_string(fdt, nodename, "status", "okay");

        qemu_fdt_setprop_cell(fdt, nodename, "reg", cpu);

        qemu_fdt_setprop_string(fdt, nodename, "device_type", "cpu");

        qemu_fdt_setprop_cell(fdt, nodename, "phandle", cpu_phandle);

        qemu_fdt_setprop_cell(fdt, nodename, "linux,phandle", cpu_phandle);

        intc_phandle = phandle++;

        qemu_fdt_add_subnode(fdt, intc);

        qemu_fdt_setprop_cell(fdt, intc, "phandle", cpu_phandle);

        qemu_fdt_setprop_cell(fdt, intc, "linux,phandle", cpu_phandle);

        qemu_fdt_setprop_cell(fdt, intc, "phandle", intc_phandle);

        qemu_fdt_setprop_cell(fdt, intc, "linux,phandle", intc_phandle);

        qemu_fdt_setprop_string(fdt, intc, "compatible", "riscv,cpu-intc");

        qemu_fdt_setprop(fdt, intc, "interrupt-controller", NULL, 0);

        qemu_fdt_setprop_cell(fdt, intc, "#interrupt-cells", 1);
@@ -214,6 +218,20 @@ static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap, 
        g_free(nodename);

    }



    /* Add cpu-topology node */

    qemu_fdt_add_subnode(fdt, "/cpus/cpu-map");

    qemu_fdt_add_subnode(fdt, "/cpus/cpu-map/cluster0");

    for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {

        char *core_nodename = g_strdup_printf("/cpus/cpu-map/cluster0/core%d",

                                              cpu);

        char *cpu_nodename = g_strdup_printf("/cpus/cpu@%d", cpu);

        uint32_t intc_phandle = qemu_fdt_get_phandle(fdt, cpu_nodename);

        qemu_fdt_add_subnode(fdt, core_nodename);

        qemu_fdt_setprop_cell(fdt, core_nodename, "cpu", intc_phandle);

        g_free(core_nodename);

        g_free(cpu_nodename);

    }



    cells =  g_new0(uint32_t, s->soc.num_harts * 4);

    for (cpu = 0; cpu < s->soc.num_harts; cpu++) {

        nodename =