Re: [RFC PATCH v2 09/13] hw/arm/virt-acpi-build: add PPTT table

From: Andrew Jones <drjones@redhat.com>
To: Ying Fang <fangying1@huawei.com>
Cc: peter.maydell@linaro.org, zhang.zhanghailiang@huawei.com,
	qemu-devel@nongnu.org, alex.chen@huawei.com,
	shannon.zhaosl@gmail.com, qemu-arm@nongnu.org,
	alistair.francis@wdc.com, imammedo@redhat.com
Subject: Re: [RFC PATCH v2 09/13] hw/arm/virt-acpi-build: add PPTT table
Date: Thu, 29 Oct 2020 17:56:14 +0100	[thread overview]
Message-ID: <20201029165614.mbwv26bnx6ntughx@kamzik.brq.redhat.com> (raw)
In-Reply-To: <20201020131440.1090-10-fangying1@huawei.com>

On Tue, Oct 20, 2020 at 09:14:36PM +0800, Ying Fang wrote:
> Add the Processor Properties Topology Table (PPTT) to present CPU topology
> information to the guest.
> 
> Signed-off-by: Andrew Jones <drjones@redhat.com>

I don't know why I have an s-o-b here. I guess it's because this code
looks nearly identical to what I wrote, except for using the new and,
IMO, unnecessary build_socket_hierarchy and build_smt_hierarchy functions.

IMHO, you should drop the last patch and just take 

https://github.com/rhdrjones/qemu/commit/439b38d67ca1f2cbfa5b9892a822b651ebd05c11

as it is, unless it needs to be fixed somehow.

Thanks,
drew

> Signed-off-by: Ying Fang <fangying1@huawei.com>
> ---
>  hw/arm/virt-acpi-build.c | 42 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index fae5a26741..e1f3ea50ad 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -429,6 +429,42 @@ build_srat(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
>                   "SRAT", table_data->len - srat_start, 3, NULL, NULL);
>  }
>  
> +static void build_pptt(GArray *table_data, BIOSLinker *linker, MachineState *ms)
> +{
> +    int pptt_start = table_data->len;
> +    int uid = 0, cpus = 0, socket;
> +    unsigned int smp_cores = ms->smp.cores;
> +    unsigned int smp_threads = ms->smp.threads;
> +
> +    acpi_data_push(table_data, sizeof(AcpiTableHeader));
> +
> +    for (socket = 0; cpus < ms->possible_cpus->len; socket++) {
> +        uint32_t socket_offset = table_data->len - pptt_start;
> +        int core;
> +
> +        build_socket_hierarchy(table_data, 0, socket);
> +
> +        for (core = 0; core < smp_cores; core++) {
> +            uint32_t core_offset = table_data->len - pptt_start;
> +            int thread;
> +
> +            if (smp_threads <= 1) {
> +                build_processor_hierarchy(table_data, 2, socket_offset, uid++);
> +             } else {
> +                build_processor_hierarchy(table_data, 0, socket_offset, core);
> +                for (thread = 0; thread < smp_threads; thread++) {
> +                    build_smt_hierarchy(table_data, core_offset, uid++);
> +                }
> +             }
> +        }
> +        cpus += smp_cores * smp_threads;
> +    }
> +
> +    build_header(linker, table_data,
> +                 (void *)(table_data->data + pptt_start), "PPTT",
> +                 table_data->len - pptt_start, 2, NULL, NULL);
> +}
> +
>  /* GTDT */
>  static void
>  build_gtdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
> @@ -669,6 +705,7 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
>      unsigned dsdt, xsdt;
>      GArray *tables_blob = tables->table_data;
>      MachineState *ms = MACHINE(vms);
> +    bool cpu_topology_enabled = !vmc->ignore_cpu_topology;
>  
>      table_offsets = g_array_new(false, true /* clear */,
>                                          sizeof(uint32_t));
> @@ -688,6 +725,11 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
>      acpi_add_table(table_offsets, tables_blob);
>      build_madt(tables_blob, tables->linker, vms);
>  
> +    if (cpu_topology_enabled) {
> +        acpi_add_table(table_offsets, tables_blob);
> +        build_pptt(tables_blob, tables->linker, ms);
> +    }
> +
>      acpi_add_table(table_offsets, tables_blob);
>      build_gtdt(tables_blob, tables->linker, vms);
>  
> -- 
> 2.23.0
> 
> 