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

[Atish Patra]

On Mon, 2019-06-24 at 16:24 -0700, Alistair Francis wrote:
> On Mon, Jun 24, 2019 at 3:57 PM Atish Patra <address@hidden>
> 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 <address@hidden>
> > ---
> >  hw/riscv/virt.c | 21 +++++++++++++++++++--
> >  1 file changed, 19 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/riscv/virt.c b/hw/riscv/virt.c
> > index 84d94d0c42d8..da0b8aa18747 100644
> > --- a/hw/riscv/virt.c
> > +++ b/hw/riscv/virt.c
> > @@ -203,9 +203,12 @@ 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);
> > +        int intc_phandle = phandle++;
> 
> Don't declare variables in the middle of code. The variable must be
> declared at the start of a block.
> 
My bad. Fixed in v2.

> With that fixed:
> 
> Reviewed-by: Alistair Francis <address@hidden>
> 
> Alistair
> 
> >          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 +217,20 @@ 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
> > 
> > 
-- 
Regards,
Atish