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.
