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hw/arm/virt: Add cpu-map to device tree

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Support device tree CPU topology descriptions.

In accordance with the Devicetree Specification, the Linux Doc
"arm/cpus.yaml" requires that cpus and cpu nodes in the DT are
present. And we have already met the requirement by generating
/cpus/cpu@* nodes for members within ms->smp.cpus. Accordingly,
we should also create subnodes in cpu-map for the present cpus,
each of which relates to an unique cpu node.

The Linux Doc "cpu/cpu-topology.txt" states that the hierarchy
of CPUs in a SMP system is defined through four entities and
they are socket/cluster/core/thread. It is also required that
a socket node's child nodes must be one or more cluster nodes.
Given that currently we are only provided with information of
socket/core/thread, we assume there is one cluster child node
in each socket node when creating cpu-map.

Co-developed-by: Yanan Wang <wangyanan55@huawei.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
Message-Id: <20211020142125.7516-4-wangyanan55@huawei.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Andrew Jones 2021-10-20 22:21:20 +08:00 committed by Richard Henderson
parent b863f0b758
commit 72b0527ff6
1 changed files with 60 additions and 10 deletions
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70
hw/arm/virt.c
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@ -351,20 +351,21 @@ 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
* 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
* in the system, #address-cells can be set to 1, since
* MPIDR_EL1[63:32] bits are not used for CPUs
* identification.
* 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
* in the system, #address-cells can be set to 1, since
* MPIDR_EL1[63:32] bits are not used for CPUs
* identification.
*
* Here we actually don't know whether our system is 32- or 64-bit one.
* The simplest way to go is to examine affinity IDs of all our CPUs. If
* at least one of them has Aff3 populated, we set #address-cells to 2.
* Here we actually don't know whether our system is 32- or 64-bit one.
* The simplest way to go is to examine affinity IDs of all our CPUs. If
* at least one of them has Aff3 populated, we set #address-cells to 2.
*/
for (cpu = 0; cpu < smp_cpus; cpu++) {
ARMCPU *armcpu = ARM_CPU(qemu_get_cpu(cpu));
@ -407,8 +408,57 @@ static void fdt_add_cpu_nodes(const VirtMachineState *vms)
ms->possible_cpus->cpus[cs->cpu_index].props.node_id);
}
if (!vmc->no_cpu_topology) {
qemu_fdt_setprop_cell(ms->fdt, nodename, "phandle",
qemu_fdt_alloc_phandle(ms->fdt));
}
g_free(nodename);
}
if (!vmc->no_cpu_topology) {
/*
* Add vCPU topology description through fdt node cpu-map.
*
* See Linux Documentation/devicetree/bindings/cpu/cpu-topology.txt
* In a SMP system, the hierarchy of CPUs can be defined through
* four entities that are used to describe the layout of CPUs in
* the system: socket/cluster/core/thread.
*
* A socket node represents the boundary of system physical package
* and its child nodes must be one or more cluster nodes. A system
* can contain several layers of clustering within a single physical
* package and cluster nodes can be contained in parent cluster nodes.
*
* Given that cluster is not yet supported in the vCPU topology,
* we currently generate one cluster node within each socket node
* by default.
*/
qemu_fdt_add_subnode(ms->fdt, "/cpus/cpu-map");
for (cpu = 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/socket%d/cluster0/core%d/thread%d",
cpu / (ms->smp.cores * ms->smp.threads),
(cpu / ms->smp.threads) % ms->smp.cores,
cpu % ms->smp.threads);
} else {
map_path = g_strdup_printf(
"/cpus/cpu-map/socket%d/cluster0/core%d",
cpu / ms->smp.cores,
cpu % ms->smp.cores);
}
qemu_fdt_add_path(ms->fdt, map_path);
qemu_fdt_setprop_phandle(ms->fdt, map_path, "cpu", cpu_path);
g_free(map_path);
g_free(cpu_path);
}
}
}
static void fdt_add_its_gic_node(VirtMachineState *vms)