On Tue, 12 Nov 2024 10:17:33 +0800
Bibo Mao <maob...@loongson.cn> wrote:
> Add topological relationships for Loongarch VCPU and initialize
> topology member variables. Also physical cpu id calculation
> method comes from its topo information.
>
> Co-developed-by: Xianglai Li <lixiang...@loongson.cn>
> Signed-off-by: Bibo Mao <maob...@loongson.cn>
> ---
> docs/system/loongarch/virt.rst | 31 +++++++++++++++
> hw/loongarch/virt.c | 73 ++++++++++++++++++++++++++++------
> target/loongarch/cpu.c | 12 ++++++
> target/loongarch/cpu.h | 16 ++++++++
> 4 files changed, 119 insertions(+), 13 deletions(-)
>
> diff --git a/docs/system/loongarch/virt.rst b/docs/system/loongarch/virt.rst
> index 172fba079e..8daf60785f 100644
> --- a/docs/system/loongarch/virt.rst
> +++ b/docs/system/loongarch/virt.rst
> @@ -28,6 +28,37 @@ The ``qemu-system-loongarch64`` provides emulation for virt
> machine. You can specify the machine type ``virt`` and
> cpu type ``la464``.
>
> +CPU Topology
> +------------
> +
> +The ``LA464`` type CPUs have the concept of Socket Core and Thread.
> +
> +For example:
> +
> +``-smp 1,maxcpus=M,sockets=S,cores=C,threads=T``
> +
> +The above parameters indicate that the machine has a maximum of ``M`` vCPUs
> and
> +``S`` sockets, each socket has ``C`` cores, each core has ``T`` threads,
> +and each thread corresponds to a vCPU.
> +
> +Then ``M`` ``S`` ``C`` ``T`` has the following relationship:
> +
> +``M = S * C * T``
> +
> +In the CPU topology relationship, When we know the ``socket_id`` ``core_id``
> +and ``thread_id`` of the CPU, we can calculate its ``arch_id``:
> +
> +``arch_id = (socket_id * S) + (core_id * C) + (thread_id * T)``
Is there a spec or some other reference where all of this is described?
(or is that a made up just for QEMU?)
> +
> +Similarly, when we know the ``arch_id`` of the CPU,
> +we can also get its ``socket_id`` ``core_id`` and ``thread_id``:
> +
> +``socket_id = arch_id / (C * T)``
> +
> +``core_id = (arch_id / T) % C``
> +
> +``thread_id = arch_id % T``
> +
> Boot options
> ------------
>
> diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
> index 9a635d1d3d..1ed5130edf 100644
> --- a/hw/loongarch/virt.c
> +++ b/hw/loongarch/virt.c
> @@ -1143,9 +1143,9 @@ static void virt_init(MachineState *machine)
> LoongArchVirtMachineState *lvms = LOONGARCH_VIRT_MACHINE(machine);
> int i;
> hwaddr base, size, ram_size = machine->ram_size;
> - const CPUArchIdList *possible_cpus;
> MachineClass *mc = MACHINE_GET_CLASS(machine);
> CPUState *cpu;
> + Object *cpuobj;
>
> if (!cpu_model) {
> cpu_model = LOONGARCH_CPU_TYPE_NAME("la464");
> @@ -1163,13 +1163,30 @@ static void virt_init(MachineState *machine)
> memory_region_add_subregion(&lvms->system_iocsr, 0, &lvms->iocsr_mem);
>
> /* Init CPUs */
> - possible_cpus = mc->possible_cpu_arch_ids(machine);
I'd keep this, and use below, it makes line shorter
> - for (i = 0; i < possible_cpus->len; i++) {
> - cpu = cpu_create(machine->cpu_type);
> + mc->possible_cpu_arch_ids(machine);
> + for (i = 0; i < machine->smp.cpus; i++) {
> + cpuobj = object_new(machine->cpu_type);
> + if (cpuobj == NULL) {
> + error_report("Fail to create object with type %s ",
> + machine->cpu_type);
> + exit(EXIT_FAILURE);
> + }
> +
> + cpu = CPU(cpuobj);
> cpu->cpu_index = i;
this probably should be in _pre_plug handler,
also see
(a15d2728a9aa pc: Init CPUState->cpu_index with index in possible_cpus[])
for why x86 does it.
> machine->possible_cpus->cpus[i].cpu = cpu;
> - lacpu = LOONGARCH_CPU(cpu);
> + lacpu = LOONGARCH_CPU(cpuobj);
> lacpu->phy_id = machine->possible_cpus->cpus[i].arch_id;
Given above is derived from topo data set below, I'd move above above
to pre_plug time, and calculate/set it there based on topo data.
There is no point in setting both at the same place.
> + object_property_set_int(cpuobj, "socket-id",
> +
> machine->possible_cpus->cpus[i].props.socket_id,
> + NULL);
> + object_property_set_int(cpuobj, "core-id",
> +
> machine->possible_cpus->cpus[i].props.core_id,
> + NULL);
> + object_property_set_int(cpuobj, "thread-id",
> +
> machine->possible_cpus->cpus[i].props.thread_id,
> + NULL);
> + qdev_realize_and_unref(DEVICE(cpuobj), NULL, &error_fatal);
> }
> fdt_add_cpu_nodes(lvms);
> fdt_add_memory_nodes(machine);
> @@ -1286,6 +1303,35 @@ static void virt_initfn(Object *obj)
> virt_flash_create(lvms);
> }
>
> +static int virt_get_arch_id_from_topo(MachineState *ms, LoongArchCPUTopo
> *topo)
> +{
> + int arch_id, sock_vcpu_num, core_vcpu_num;
> +
> + /*
> + * calculate total logical cpus across socket/core/thread.
> + * For more information on how to calculate the arch_id,
> + * you can refer to the CPU Topology chapter of the
> + * docs/system/loongarch/virt.rst document.
> + */
> + sock_vcpu_num = topo->socket_id * (ms->smp.threads * ms->smp.cores);
> + core_vcpu_num = topo->core_id * ms->smp.threads;
> +
> + /* get vcpu-id(logical cpu index) for this vcpu from this topology */
> + arch_id = (sock_vcpu_num + core_vcpu_num) + topo->thread_id;
> +
> + assert(arch_id >= 0 && arch_id < ms->possible_cpus->len);
> +
> + return arch_id;
> +}
> +
> +static void virt_get_topo_from_index(MachineState *ms,
> + LoongArchCPUTopo *topo, int index)
> +{
> + topo->socket_id = index / (ms->smp.cores * ms->smp.threads);
> + topo->core_id = index / ms->smp.threads % ms->smp.cores;
> + topo->thread_id = index % ms->smp.threads;
> +}
> +
> static bool memhp_type_supported(DeviceState *dev)
> {
> /* we only support pc dimm now */
> @@ -1385,8 +1431,9 @@ static HotplugHandler
> *virt_get_hotplug_handler(MachineState *machine,
>
> static const CPUArchIdList *virt_possible_cpu_arch_ids(MachineState *ms)
> {
> - int n;
> + int n, arch_id;
> unsigned int max_cpus = ms->smp.max_cpus;
> + LoongArchCPUTopo topo;
>
> if (ms->possible_cpus) {
> assert(ms->possible_cpus->len == max_cpus);
> @@ -1397,17 +1444,17 @@ static const CPUArchIdList
> *virt_possible_cpu_arch_ids(MachineState *ms)
> sizeof(CPUArchId) * max_cpus);
> ms->possible_cpus->len = max_cpus;
> for (n = 0; n < ms->possible_cpus->len; n++) {
> + virt_get_topo_from_index(ms, &topo, n);
> + arch_id = virt_get_arch_id_from_topo(ms, &topo);
> + ms->possible_cpus->cpus[n].vcpus_count = 1;
> ms->possible_cpus->cpus[n].type = ms->cpu_type;
> - ms->possible_cpus->cpus[n].arch_id = n;
> -
> + ms->possible_cpus->cpus[n].arch_id = arch_id;
> ms->possible_cpus->cpus[n].props.has_socket_id = true;
> - ms->possible_cpus->cpus[n].props.socket_id =
> - n / (ms->smp.cores * ms->smp.threads);
> + ms->possible_cpus->cpus[n].props.socket_id = topo.socket_id;
> ms->possible_cpus->cpus[n].props.has_core_id = true;
> - ms->possible_cpus->cpus[n].props.core_id =
> - n / ms->smp.threads % ms->smp.cores;
> + ms->possible_cpus->cpus[n].props.core_id = topo.core_id;
> ms->possible_cpus->cpus[n].props.has_thread_id = true;
> - ms->possible_cpus->cpus[n].props.thread_id = n % ms->smp.threads;
> + ms->possible_cpus->cpus[n].props.thread_id = topo.thread_id;
> }
> return ms->possible_cpus;
> }
> diff --git a/target/loongarch/cpu.c b/target/loongarch/cpu.c
> index 57cc4f314b..a99e22094e 100644
> --- a/target/loongarch/cpu.c
> +++ b/target/loongarch/cpu.c
> @@ -16,6 +16,7 @@
> #include "kvm/kvm_loongarch.h"
> #include "exec/exec-all.h"
> #include "cpu.h"
> +#include "hw/qdev-properties.h"
> #include "internals.h"
> #include "fpu/softfloat-helpers.h"
> #include "cpu-csr.h"
> @@ -725,6 +726,7 @@ static void loongarch_cpu_init(Object *obj)
> timer_init_ns(&cpu->timer, QEMU_CLOCK_VIRTUAL,
> &loongarch_constant_timer_cb, cpu);
> #endif
> + cpu->phy_id = UNSET_PHY_ID;
> #endif
> }
>
> @@ -823,6 +825,14 @@ static int64_t loongarch_cpu_get_arch_id(CPUState *cs)
> }
> #endif
>
> +static Property loongarch_cpu_properties[] = {
> + DEFINE_PROP_INT32("socket-id", LoongArchCPU, socket_id, 0),
> + DEFINE_PROP_INT32("core-id", LoongArchCPU, core_id, 0),
> + DEFINE_PROP_INT32("thread-id", LoongArchCPU, thread_id, 0),
> + DEFINE_PROP_INT32("node-id", LoongArchCPU, node_id,
> CPU_UNSET_NUMA_NODE_ID),
> + DEFINE_PROP_END_OF_LIST()
> +};
> +
> static void loongarch_cpu_class_init(ObjectClass *c, void *data)
> {
> LoongArchCPUClass *lacc = LOONGARCH_CPU_CLASS(c);
> @@ -830,6 +840,7 @@ static void loongarch_cpu_class_init(ObjectClass *c, void
> *data)
> DeviceClass *dc = DEVICE_CLASS(c);
> ResettableClass *rc = RESETTABLE_CLASS(c);
>
> + device_class_set_props(dc, loongarch_cpu_properties);
> device_class_set_parent_realize(dc, loongarch_cpu_realizefn,
> &lacc->parent_realize);
> resettable_class_set_parent_phases(rc, NULL, loongarch_cpu_reset_hold,
> NULL,
> @@ -854,6 +865,7 @@ static void loongarch_cpu_class_init(ObjectClass *c, void
> *data)
> #ifdef CONFIG_TCG
> cc->tcg_ops = &loongarch_tcg_ops;
> #endif
> + dc->user_creatable = true;
> }
>
> static const gchar *loongarch32_gdb_arch_name(CPUState *cs)
> diff --git a/target/loongarch/cpu.h b/target/loongarch/cpu.h
> index 86c86c6c95..7472df0521 100644
> --- a/target/loongarch/cpu.h
> +++ b/target/loongarch/cpu.h
> @@ -19,6 +19,12 @@
> #include "cpu-csr.h"
> #include "cpu-qom.h"
>
> +/*
> + * CPU can't have 0xFFFFFFFF physical ID, use that value to distinguish
> + * that physical ID hasn't been set yet
pointer to CPU spec/doc here would be nice to have
> + */
> +#define UNSET_PHY_ID 0xFFFFFFFF
> +
> #define IOCSRF_TEMP 0
> #define IOCSRF_NODECNT 1
> #define IOCSRF_MSI 2
> @@ -390,6 +396,12 @@ typedef struct CPUArchState {
> #endif
> } CPULoongArchState;
>
> +typedef struct LoongArchCPUTopo {
> + int32_t socket_id; /* socket-id of this VCPU */
> + int32_t core_id; /* core-id of this VCPU */
> + int32_t thread_id; /* thread-id of this VCPU */
> +} LoongArchCPUTopo;
> +
> /**
> * LoongArchCPU:
> * @env: #CPULoongArchState
> @@ -404,6 +416,10 @@ struct ArchCPU {
> uint32_t phy_id;
> OnOffAuto lbt;
> OnOffAuto pmu;
> + int32_t socket_id; /* socket-id of this VCPU */
> + int32_t core_id; /* core-id of this VCPU */
> + int32_t thread_id; /* thread-id of this VCPU */
> + int32_t node_id; /* NUMA node of this VCPU */
>
> /* 'compatible' string for this CPU for Linux device trees */
> const char *dtb_compatible;
