Re: [PATCH v5 3/3] pc: q35: Bump max_cpus to 1024

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 6 Jun 2023 21:49:39 -0500
Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> wrote:

> Since KVM_MAX_VCPUS is currently defined to 1024 for x86 as shown in
> arch/x86/include/asm/kvm_host.h, update QEMU limits to the same number.
> 
> In case KVM could not support the specified number of vcpus, QEMU would
> return the following error message:
> 
>   qemu-system-x86_64: kvm_init_vcpu: kvm_get_vcpu failed (xxx): Invalid argument
> 
> Also, keep max_cpus at 288 for machine version 8.0 and older.
> 
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Daniel P. Berrangé <berrange@redhat.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Julia Suvorova <jusual@redhat.com>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> ---
>  hw/i386/pc_q35.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 371cca7484..63866a16e0 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -360,12 +360,12 @@ static void pc_q35_machine_options(MachineClass *m)
>      m->default_nic = "e1000e";
>      m->default_kernel_irqchip_split = false;
>      m->no_floppy = 1;
> +    m->max_cpus = 1024;
>      m->no_parallel = !module_object_class_by_name(TYPE_ISA_PARALLEL);
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_AMD_IOMMU_DEVICE);
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_INTEL_IOMMU_DEVICE);
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_RAMFB_DEVICE);
>      machine_class_allow_dynamic_sysbus_dev(m, TYPE_VMBUS_BRIDGE);
> -    m->max_cpus = 288;
>  }
>  
>  static void pc_q35_8_1_machine_options(MachineClass *m)
> @@ -388,6 +388,7 @@ static void pc_q35_8_0_machine_options(MachineClass *m)
>  
>      /* For pc-q35-8.0 and older, use SMBIOS 2.8 by default */
>      pcmc->default_smbios_ep_type = SMBIOS_ENTRY_POINT_TYPE_32;
> +    m->max_cpus = 288;
>  }
>  
>  DEFINE_Q35_MACHINE(v8_0, "pc-q35-8.0", NULL,