From: Joao Martins <joao.m.martins@oracle.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>,
qemu-devel@nongnu.org
Cc: pbonzini@redhat.com, richard.henderson@linaro.org,
eduardo@habkost.net, mst@redhat.com, marcel.apfelbaum@gmail.com,
imammedo@redhat.com, berrange@redhat.com, jusual@redhat.com,
jon.grimm@amd.com, santosh.Shukla@amd.com
Subject: Re: [PATCH v2] pc: q35: Bump max_cpus to 1024
Date: Thu, 1 Jun 2023 11:09:45 +0100 [thread overview]
Message-ID: <39a49814-28d8-ffc8-42b4-3af14bb9dd47@oracle.com> (raw)
In-Reply-To: <20230531225127.331998-1-suravee.suthikulpanit@amd.com>
On 31/05/2023 23:51, Suravee Suthikulpanit 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
>
> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> ---
>
> Changes from V1:
> (https://lore.kernel.org/all/YnkDGsIi1vFvXmiP@redhat.com/T/)
> * Bump from 512 to KVM_MAX_VCPUS (per Igor's suggestion)
>
> Note:
> From the last discussion, Daniel mentioned that SMBIO 2.1 tables might
> cause overflow at approx 720 CPUs, and it might require using the
> SMBIO 3.0 entry point. Also, we might need to change the default for
> the x86 machine type to SMBIO 3.0. However, I do not know the status
> of this.
>
I suspect smbios 3.0 (64-bit entry point) is already supported.
With current qemu and all the smbios fixes in the last cycle, perhaps this is
mainly just setting smbios_entry_point_type to SMBIOS_ENTRY_POINT_TYPE_64 if
MachineState::smp::max_cpus is bigger than 720 (e.g. in pc_q35_init()?)
> Thank you,
> Suravee
>
> hw/i386/pc_q35.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index f02919d92c..e7dc226bd5 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -370,7 +370,7 @@ static void pc_q35_machine_options(MachineClass *m)
> 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;
> + m->max_cpus = 1024;
> }
>
> static void pc_q35_8_1_machine_options(MachineClass *m)
next prev parent reply other threads:[~2023-06-01 10:10 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-31 22:51 [PATCH v2] pc: q35: Bump max_cpus to 1024 Suravee Suthikulpanit
2023-06-01 10:09 ` Joao Martins [this message]
2023-06-01 10:17 ` Daniel P. Berrangé
2023-06-01 11:03 ` Gerd Hoffmann
2023-06-01 11:09 ` Michael S. Tsirkin
2023-06-01 21:54 ` Suthikulpanit, Suravee
2023-06-02 8:43 ` Daniel P. Berrangé
-- strict thread matches above, loose matches on Subject: below --
2022-11-18 8:55 Dario Faggioli
2022-11-18 9:18 ` Daniel P. Berrangé
2022-11-18 9:43 ` Gerd Hoffmann
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