On Fri, Apr 12, 2024, Wujie Duan wrote: > Add a pre-allocation arch condition to checks that vcpu id should > smaller than max_vcpus > > Signed-off-by: Wujie Duan <wjduan@xxxxxxxxxxxxx> > --- > arch/loongarch/kvm/vcpu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c > index 3a8779065f73..d41cacf39583 100644 > --- a/arch/loongarch/kvm/vcpu.c > +++ b/arch/loongarch/kvm/vcpu.c > @@ -884,6 +884,9 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp, > > int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id) > { > + if (id >= kvm->max_vcpus) > + return -EINVAL; Do you have a testcase for this? If I'm following the LoongArch code correctly, I don't think this is actually necessary. In arch/loongarch/include/asm/kvm_host.h: #define KVM_MAX_VCPUS 256 without a #define KVM_MAX_VCPU_IDS in loongarch/, AFAICT. And so the common code in include/linux/kvm_host.h will do: #ifndef KVM_MAX_VCPU_IDS #define KVM_MAX_VCPU_IDS KVM_MAX_VCPUS #endif LoongArch's kvm_vm_ioctl_check_extension() reports that to userspace: case KVM_CAP_MAX_VCPU_ID: r = KVM_MAX_VCPU_IDS; and the common kvm_vm_ioctl_create_vcpu() does: if (id >= KVM_MAX_VCPU_IDS) return -EINVAL; and the common kvm_create_vm() does: kvm->max_vcpus = KVM_MAX_VCPUS; with again no override of max_vcpus in LoongArch or common KVM. So unless I'm missing something, manually checking max_vcpus in LoongArch's kvm_arch_vcpu_precreate() is unnecessary.