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[Qemu-devel] [PATCH v2] riscv: virt: Add cpu-topology DT node.

Atish Patra posted 1 patch 4 years, 9 months ago
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git fetch https://github.com/patchew-project/qemu tags/patchew/20190624234144.10768-1-atish.patra@wdc.com
Maintainers: Alistair Francis <Alistair.Francis@wdc.com>, Palmer Dabbelt <palmer@sifive.com>, Sagar Karandikar <sagark@eecs.berkeley.edu>, Bastian Koppelmann <kbastian@mail.uni-paderborn.de>
hw/riscv/virt.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
[Qemu-devel] [PATCH v2] riscv: virt: Add cpu-topology DT node.
Posted by Atish Patra 4 years, 9 months ago 
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: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
---
 hw/riscv/virt.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
index 84d94d0c42d8..45a1edcd6c4a 100644
--- a/hw/riscv/virt.c
+++ b/hw/riscv/virt.c
@@ -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 =
-- 
2.21.0
Re: [Qemu-devel] [PATCH v2] riscv: virt: Add cpu-topology DT node.
Posted by Palmer Dabbelt 4 years, 9 months ago 
On Mon, 24 Jun 2019 16:41:44 PDT (-0700), Atish Patra wrote:
> 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: Atish Patra <atish.patra@wdc.com>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Thanks.  This is in the queue for 4.1, which is just pending Alistar's review
on those two Z patches I reworked.

> ---
>  hw/riscv/virt.c | 22 ++++++++++++++++++++--
>  1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> index 84d94d0c42d8..45a1edcd6c4a 100644
> --- a/hw/riscv/virt.c
> +++ b/hw/riscv/virt.c
> @@ -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 =

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