Re: [Qemu-devel] [RFC 12/12] pc: Generate APIC IDs according to CPU topology

[Igor Mammedov <imammedo@redhat.com>]

On Wed,  9 Jan 2013 16:53:52 -0200
Eduardo Habkost <ehabkost@redhat.com> wrote:

> This keeps compatibility on machine-types pc-1.2 and older, and prints a
> warning in case the requested configuration won't get the correct
> topology.
> 
> I couldn't think of a better way to warn about broken topology when in
> compat mode other than using error_report(). The warning message will be
> probably be buried in a log file somewhere, but it's better than
> nothing.
> 
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> Changes v1 -> v2:
>  - Move code to cpu.c
>  - keep using cpu_index on *-user
>  - Use SMP.contiguous_apic_ids global property
>  - Prints warning in case the compatibility mode will expose incorrect
>    topology
> 
> Changes v2 -> v3:
>  - Now all code is inside hw/pc.c
>  - Use a real "PC" class and a "contiguous_apic_ids" property
> 
> Changes v3 -> v4:
>  - Instead of using a global property, use a separate machine init
>    function and a PCInitArgs field, to implement compatibility mode
>  - Use error_report() instead of fprintf(stderr) for the warning
>  - Use a field on PCInitArgs instead of a static variable to check
>    if warning was already printed
> 
> Changes v4 -> v5:
>  - Don't use PCInitArgs: simply add a enable_compat_apic_id_mode()
>    function and a static compat_apic_id_mode variable, to enable the
>    compatibility mode
>  - Move APIC ID calculation code to cpu.c
> ---
>  hw/pc_piix.c      | 13 +++++++++++--
>  target-i386/cpu.c | 28 ++++++++++++++++++++++++----
>  target-i386/cpu.h |  1 +
>  3 files changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/pc_piix.c b/hw/pc_piix.c
> index 13d7cc8..be4fea1 100644
> --- a/hw/pc_piix.c
> +++ b/hw/pc_piix.c
> @@ -233,11 +233,18 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
>               initrd_filename, cpu_model, 1, 1);
>  }
>  
> +
> +static void pc_init_pci_1_3(QEMUMachineInitArgs *args)
> +{
> +    enable_compat_apic_id_mode();
> +    pc_init_pci(args);
> +}
> +
>  /* PC machine init function for pc-0.14 to pc-1.2 */
>  static void pc_init_pci_1_2(QEMUMachineInitArgs *args)
>  {
>      disable_kvm_pv_eoi();
> -    pc_init_pci(args);
> +    pc_init_pci_1_3(args);
>  }
>  
>  /* PC init function for pc-0.10 to pc-0.13, and reused by xenfv */
> @@ -250,6 +257,7 @@ static void pc_init_pci_no_kvmclock(QEMUMachineInitArgs *args)
>      const char *initrd_filename = args->initrd_filename;
>      const char *boot_device = args->boot_device;
>      disable_kvm_pv_eoi();
> +    enable_compat_apic_id_mode();
>      pc_init1(get_system_memory(),
>               get_system_io(),
>               ram_size, boot_device,
> @@ -268,6 +276,7 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
>      if (cpu_model == NULL)
>          cpu_model = "486";
>      disable_kvm_pv_eoi();
> +    enable_compat_apic_id_mode();
>      pc_init1(get_system_memory(),
>               get_system_io(),
>               ram_size, boot_device,
> @@ -305,7 +314,7 @@ static QEMUMachine pc_machine_v1_4 = {
>  static QEMUMachine pc_machine_v1_3 = {
>      .name = "pc-1.3",
>      .desc = "Standard PC",
> -    .init = pc_init_pci,
> +    .init = pc_init_pci_1_3,
>      .max_cpus = 255,
>      .compat_props = (GlobalProperty[]) {
>          PC_COMPAT_1_3,
> diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> index 33787dc..f34192c 100644
> --- a/target-i386/cpu.c
> +++ b/target-i386/cpu.c
> @@ -23,6 +23,8 @@
>  
>  #include "cpu.h"
>  #include "sysemu/kvm.h"
> +#include "sysemu/cpus.h"
> +#include "topology.h"
>  
>  #include "qemu/option.h"
>  #include "qemu/config-file.h"
> @@ -2192,6 +2194,14 @@ void x86_cpu_realize(Object *obj, Error **errp)
>      cpu_reset(CPU(cpu));
>  }
>  
> +/* Enables contiguous-apic-ID mode, for compatibility */
> +static bool compat_apic_id_mode;
> +
> +void enable_compat_apic_id_mode(void)
> +{
> +    compat_apic_id_mode = true;
> +}
> +
>  /* Calculates initial APIC ID for a specific CPU index
>   *
>   * Currently we need to be able to calculate the APIC ID from the CPU index
> @@ -2201,10 +2211,20 @@ void x86_cpu_realize(Object *obj, Error **errp)
>   */
>  uint32_t apic_id_for_cpu(unsigned int cpu_index)
if you move ^^^ to board, there won't be need in [8/12]
>  {
> -    /* right now APIC ID == CPU index. this will eventually change to use
> -     * the CPU topology configuration properly
> -     */
> -    return cpu_index;
> +    uint32_t correct_id;
> +    static bool warned;
> +
> +    correct_id = topo_apicid_for_cpu(smp_cores, smp_threads, cpu_index);
> +    if (compat_apic_id_mode) {
> +        if (cpu_index != correct_id && !warned) {
> +            error_report("APIC IDs set in compatibility mode, "
> +                         "CPU topology won't match the configuration");
> +            warned = true;
> +        }
> +        return cpu_index;
> +    } else {
> +        return correct_id;
> +    }
>  }
>  
>  static void x86_cpu_initfn(Object *obj)
> diff --git a/target-i386/cpu.h b/target-i386/cpu.h
> index dbd9899..d9a9e8f 100644
> --- a/target-i386/cpu.h
> +++ b/target-i386/cpu.h
> @@ -1239,5 +1239,6 @@ void disable_kvm_pv_eoi(void);
>  const char *get_register_name_32(unsigned int reg);
>  
>  uint32_t apic_id_for_cpu(unsigned int cpu_index);
> +void enable_compat_apic_id_mode(void);
>  
>  #endif /* CPU_I386_H */
> -- 
> 1.7.11.7
> 
> --
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-- 
Regards,
  Igor