Re: [PATCH v7 10/16] i386/cpu: Introduce cluster-id to X86CPU

[Xiaoyao Li <xiaoyao.li@xxxxxxxxx>]

On 1/8/2024 4:27 PM, Zhao Liu wrote:
> From: Zhuocheng Ding <zhuocheng.ding@xxxxxxxxx>
>
> Introduce cluster-id other than module-id to be consistent with
> CpuInstanceProperties.cluster-id, and this avoids the confusion
> of parameter names when hotplugging.

I don't think reusing 'cluster' from arm for x86's 'module' is a good 
idea. It introduces confusion around the code.

s390 just added 'drawer' and 'book' in cpu topology[1]. I think we can 
also add a module level for x86 instead of reusing cluster.

(This is also what I want to reply to the cover letter.)

[1] 
https://lore.kernel.org/qemu-devel/20231016183925.2384704-1-nsg@xxxxxxxxxxxxx/

> Following the legacy smp check rules, also add the cluster_id validity
> into x86_cpu_pre_plug().
>
> Signed-off-by: Zhuocheng Ding <zhuocheng.ding@xxxxxxxxx>
> Co-developed-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
> Signed-off-by: Zhao Liu <zhao1.liu@xxxxxxxxx>
> Tested-by: Babu Moger <babu.moger@xxxxxxx>
> Tested-by: Yongwei Ma <yongwei.ma@xxxxxxxxx>
> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> ---
> Changes since v6:
>   * Update the comment when check cluster-id. Since there's no
>     v8.2, the cluster-id support should at least start from v9.0.
>
> Changes since v5:
>   * Update the comment when check cluster-id. Since current QEMU is
>     v8.2, the cluster-id support should at least start from v8.3.
>
> Changes since v3:
>   * Use the imperative in the commit message. (Babu)
> ---
>   hw/i386/x86.c     | 33 +++++++++++++++++++++++++--------
>   target/i386/cpu.c |  2 ++
>   target/i386/cpu.h |  1 +
>   3 files changed, 28 insertions(+), 8 deletions(-)
>
> diff --git a/hw/i386/x86.c b/hw/i386/x86.c
> index 5269aae3a5c2..1c1d368614ee 100644
> --- a/hw/i386/x86.c
> +++ b/hw/i386/x86.c
> @@ -329,6 +329,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
>               cpu->die_id = 0;
>           }
>   
> +        /*
> +         * cluster-id was optional in QEMU 9.0 and older, so keep it optional
> +         * if there's only one cluster per die.
> +         */
> +        if (cpu->cluster_id < 0 && ms->smp.clusters == 1) {
> +            cpu->cluster_id = 0;
> +        }
> +
>           if (cpu->socket_id < 0) {
>               error_setg(errp, "CPU socket-id is not set");
>               return;
> @@ -345,6 +353,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
>                          cpu->die_id, ms->smp.dies - 1);
>               return;
>           }
> +        if (cpu->cluster_id < 0) {
> +            error_setg(errp, "CPU cluster-id is not set");
> +            return;
> +        } else if (cpu->cluster_id > ms->smp.clusters - 1) {
> +            error_setg(errp, "Invalid CPU cluster-id: %u must be in range 0:%u",
> +                       cpu->cluster_id, ms->smp.clusters - 1);
> +            return;
> +        }
>           if (cpu->core_id < 0) {
>               error_setg(errp, "CPU core-id is not set");
>               return;
> @@ -364,16 +380,9 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
>   
>           topo_ids.pkg_id = cpu->socket_id;
>           topo_ids.die_id = cpu->die_id;
> +        topo_ids.module_id = cpu->cluster_id;
>           topo_ids.core_id = cpu->core_id;
>           topo_ids.smt_id = cpu->thread_id;
> -
> -        /*
> -         * TODO: This is the temporary initialization for topo_ids.module_id to
> -         * avoid "maybe-uninitialized" compilation errors. Will remove when
> -         * X86CPU supports cluster_id.
> -         */
> -        topo_ids.module_id = 0;
> -
>           cpu->apic_id = x86_apicid_from_topo_ids(&topo_info, &topo_ids);
>       }
>   
> @@ -418,6 +427,14 @@ void x86_cpu_pre_plug(HotplugHandler *hotplug_dev,
>       }
>       cpu->die_id = topo_ids.die_id;
>   
> +    if (cpu->cluster_id != -1 && cpu->cluster_id != topo_ids.module_id) {
> +        error_setg(errp, "property cluster-id: %u doesn't match set apic-id:"
> +            " 0x%x (cluster-id: %u)", cpu->cluster_id, cpu->apic_id,
> +            topo_ids.module_id);
> +        return;
> +    }
> +    cpu->cluster_id = topo_ids.module_id;
> +
>       if (cpu->core_id != -1 && cpu->core_id != topo_ids.core_id) {
>           error_setg(errp, "property core-id: %u doesn't match set apic-id:"
>               " 0x%x (core-id: %u)", cpu->core_id, cpu->apic_id,
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index a2d39d2198b6..498a4be62b40 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -7909,12 +7909,14 @@ static Property x86_cpu_properties[] = {
>       DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, 0),
>       DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, 0),
>       DEFINE_PROP_INT32("core-id", X86CPU, core_id, 0),
> +    DEFINE_PROP_INT32("cluster-id", X86CPU, cluster_id, 0),
>       DEFINE_PROP_INT32("die-id", X86CPU, die_id, 0),
>       DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, 0),
>   #else
>       DEFINE_PROP_UINT32("apic-id", X86CPU, apic_id, UNASSIGNED_APIC_ID),
>       DEFINE_PROP_INT32("thread-id", X86CPU, thread_id, -1),
>       DEFINE_PROP_INT32("core-id", X86CPU, core_id, -1),
> +    DEFINE_PROP_INT32("cluster-id", X86CPU, cluster_id, -1),
>       DEFINE_PROP_INT32("die-id", X86CPU, die_id, -1),
>       DEFINE_PROP_INT32("socket-id", X86CPU, socket_id, -1),
>   #endif
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 97b290e10576..009950b87203 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -2057,6 +2057,7 @@ struct ArchCPU {
>       int32_t node_id; /* NUMA node this CPU belongs to */
>       int32_t socket_id;
>       int32_t die_id;
> +    int32_t cluster_id;
>       int32_t core_id;
>       int32_t thread_id;
>