On Thu, Feb 25, 2021 at 09:18:22PM +0800, Ying Fang wrote:
>
>
> On 2/25/2021 7:16 PM, Andrew Jones wrote:
> > Hi Ying Fang,
> >
> > The only difference between this and what I have in my tree[*]
> > is the removal of the socket node (which has been in the Linux
> > docs since June 2019). Any reason why you removed that node? In
> > any case, I think I deserve a bit more credit for this patch.
>
> Sorry, you surely deserve it. I forget to add it here.
> Should I have a SOB of you here ?
>
> The latest linux kernel use a four level cpu topology defined in
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/cpu/cpu-topology.txt?h=v5.11
>
> ie. socket node, cluster node, core node, thread node.
Yes, this is why the code I wrote uses the 'socket' node.
>
> The linux kernel 4.19 LTS use a three level cpu topology defined in
> Documentation/devicetree/bindings/arm/topology.txt
I don't think we want to target that guest kernel with this
new QEMU feature. If we must support that guest kernel, then
I would do it under a machine property, like compat_cpumap
or something.
>
> ie. cluster node, core node, thread node.
>
> Currently Qemu x86 has 4 level of cpu topology as: socket, die, core,
> thread. Should arm64 active like it here ?
Does the arm64 guest kernel support the concept of 'die'? (I don't
think so) Anyway, there's no such concept in the current cpu-map
definition. So, if the guest kernel does support die, then what
does it map that to from DT and ACPI?
>
> Further more, latest linux kernel define the cpu topology struct as.
> So maybe it only cares about the socket, core, thread topology levels.
>
> struct cpu_topology {
>
> int thread_id;
>
> int core_id;
>
> int package_id;
>
> int llc_id;
>
> cpumask_t thread_sibling;
>
> cpumask_t core_sibling;
>
> cpumask_t llc_sibling;
>
> };
>
> >
> > [*]
> > https://github.com/rhdrjones/qemu/commit/35feecdd43475608c8f55973a0c159eac4aafefd
> >
> > Thanks,
> > drew
> >
> > On Thu, Feb 25, 2021 at 04:56:24PM +0800, Ying Fang wrote:
> > > Support device tree CPU topology descriptions.
> > >
> > > Signed-off-by: Ying Fang <fangyi...@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),
>
> a cluster node may be replaced by socket to keep accord with the latest
> kernel.
Right, in which case this patch would be identical to the one in my
branch.
Thanks,
drew
>
> > > + "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
> > >
> > >
> >
> > .
> >
>
