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Tue, 28 Apr 2026 19:17:20 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 1 X-BIZMAIL-ID: 6219295977326612698 Message-ID: <7CFC18ABD138F62B+086624ea-7d8d-411e-bd5d-4c79899c58db@uniontech.com> Date: Tue, 28 Apr 2026 19:17:20 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] LoongArch: KVM: Cap KVM_CAP_NR_VCPUS by KVM_CAP_MAX_VCPUS To: Bibo Mao , zhaotianrui@loongson.cn, chenhuacai@kernel.org, kernel@xen0n.name Cc: kvm@vger.kernel.org, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org References: <20260428074742.2274610-1-maqianga@uniontech.com> <2074ae0a-5a3a-c0b5-cd09-040696679715@loongson.cn> Content-Language: en-US From: Qiang Ma In-Reply-To: <2074ae0a-5a3a-c0b5-cd09-040696679715@loongson.cn> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-QQ-SENDSIZE: 520 Feedback-ID: esmtpgz:uniontech.com:qybglogicsvrsz:qybglogicsvrsz3b-0 X-QQ-XMAILINFO: NrtVg7D34wGAcJ5a/nlGzO7Ozr75q/E6lYy3MZipGJAE/toxMkPPMwjA e3YrmIv+1L/KYd2MxL8uwSFv5TZO3XjYKpMccuLI6TRwYvW6KDesCgQgizocV+P1X2WsbIi wKDmbWvQYiFW9xUCdcVEpkKY1sTjHiuePl0oCT9DEHx6d3aawxR2Qew9nxD5AH8oq+qmc6x CiemwhN1aXfdKfWulSccgceZPhRO1kVS4bdbNvdKhh3DRS9NadE6frYLQ2YVG+TNP84PwOa ONU+2MIzdjfLz5Bk9RgLYb+8yn7aE1nhdmy/hWB7lyDtI2jD5a7qWJKu2FePSZr3ys2IYee xXYFpBD0vrZ2Y2UI9rEpxZGNEx/n21RLBP8Xk8VleDup8DW9rHDhfphVCZelPqp7ZLwZnd3 r/CmSG8I1+nQ/77wCGXxw58iNpR5oYXqu6QP8V7nW0t1dyEmWTKGhN6qrMKYPYJiglGNDRl i1Tc1KASmMdBGB20lEpeFSnDn3VykQFGFiFEuPlTBoUUMn32Uc5ULU3Um6uBA/SCcTXWMeD mcZNABK0xf1ccMyp8vW37gnRexFPZK00bcI9SyHSLePgx7zLAU8Enx7Uje+vxm98FkHYJq6 uGtIXTLHURrJfAHL0XTLs0ZMh6h9ac5F95jJ1dTh1HDhID7CQURZxlX/VvSFlQfyOskmXhB K5+K2d0tpfiRyx6O+CTct1WyEWcTuSBlezdb2BtWjx1Nt4SaulHl2VU9+zjvz+YfpCBs9e+ gcm4pJ93E0K/uKkhSTiLn8UvU/gCBnHXX14dpHgzL4ZXhvzeF2pghF1mljU9tN67261/1uP Ih8c60YMi1ze1x6IedRq36V9SYcbx3NQ55QmCU1gRRIK1ca4GbnDy0beEqF/zX8I1RqTHjr Ckts6GoCBjQuIvGIjgb7sY88kDd/1x3mejuc344/c6n+7chiLb/BK/hvBVGF4ORWBEcj9tN 8nmfFTFyld9VdUhwSSlHFN4vssOWAb0savWZaeoRlq2pLnTjzSl+K6R8749m/1ST9IkqMxL jYaXTWbK2imrNatAMmsSPiraz3jZxQCnCouuTkCQ== X-QQ-XMRINFO: OWPUhxQsoeAVRscC/QzSek3CGsmIHPzmUw== X-QQ-RECHKSPAM: 0 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 >> --- >>   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 > >