From: Qiang Ma <maqianga@uniontech.com>
To: Bibo Mao <maobibo@loongson.cn>,
zhaotianrui@loongson.cn, chenhuacai@kernel.org,
kernel@xen0n.name
Cc: kvm@vger.kernel.org, loongarch@lists.linux.dev,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS
Date: Tue, 28 Apr 2026 19:17:20 +0800 [thread overview]
Message-ID: <7CFC18ABD138F62B+086624ea-7d8d-411e-bd5d-4c79899c58db@uniontech.com> (raw)
In-Reply-To: <2074ae0a-5a3a-c0b5-cd09-040696679715@loongson.cn>
在 2026/4/28 17:50, Bibo Mao 写道:
>
>
> On 2026/4/28 下午3:47, Qiang Ma wrote:
>> It doesn't make sense to return the recommended maximum number of
>> vCPUs which exceeds the maximum possible number of vCPUs.
>>
>> Other architectures have already done this, such as Commit
>> 57a2e13ebdda ("KVM: MIPS: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS")
>>
>> Fixes: 482795cb62aa ("LoongArch: KVM: Implement VM related functions")
>>
>> Signed-off-by: Qiang Ma <maqianga@uniontech.com>
>> ---
>> arch/loongarch/kvm/vm.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
>> index 8cc5ee1c53ef..1317c718f896 100644
>> --- a/arch/loongarch/kvm/vm.c
>> +++ b/arch/loongarch/kvm/vm.c
>> @@ -125,7 +125,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm,
>> long ext)
>> r = 1;
>> break;
>> case KVM_CAP_NR_VCPUS:
>> - r = num_online_cpus();
>> + r = min_t(unsigned int, num_online_cpus(), KVM_MAX_VCPUS);
>> break;
>> case KVM_CAP_MAX_VCPUS:
>> r = KVM_MAX_VCPUS;
>>
> Hi Qiang,
>
> yes, this is better.
>
> Though value of CONFIG_NR_CPUS is 2048, currently max CPU number of
> host hardware is 256 still because of limitation of AVEC and extioi HW
> irqchip.
>
> If there is HW machine in future which supports more than 256 CPUs,
> the max online CPU is no more than 256 with existing kernel version.
> So I think that the "Fixes" tag is not necessary.
That makes sense. Let's remove the "Fixes" tag and send out the v2 version.
>
> Reviewed-by: Bibo Mao <maobibo@loongson.cn>
>
>
prev parent reply other threads:[~2026-04-28 11:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-28 7:47 [PATCH] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS Qiang Ma
2026-04-28 9:50 ` Bibo Mao
2026-04-28 11:17 ` Qiang Ma [this message]
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