Re: [PATCH v2 1/9] KVM: x86: check validity of argument to KVM_SET_MP_STATE
From: Maxim Levitsky
Date: Mon Aug 15 2022 - 09:33:13 EST
On Thu, 2022-08-11 at 17:05 -0400, Paolo Bonzini wrote:
> An invalid argument to KVM_SET_MP_STATE has no effect other than making the
> vCPU fail to run at the next KVM_RUN. Since it is extremely unlikely that
> any userspace is relying on it, fail with -EINVAL just like for other
> architectures.
>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 132d662d9713..c44348bb6ef2 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -10653,7 +10653,8 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
> case KVM_MP_STATE_INIT_RECEIVED:
> break;
> default:
> - return -EINTR;
> + WARN_ON(1);
Very small nitpick: Maybe WARN_ON_ONCE after all?
(but I don't see any way after this patch to have invalid mp_state)
> + break;
> }
> return 1;
> }
> @@ -11094,9 +11095,22 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
>
> vcpu_load(vcpu);
>
> - if (!lapic_in_kernel(vcpu) &&
> - mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
> + switch (mp_state->mp_state) {
> + case KVM_MP_STATE_UNINITIALIZED:
> + case KVM_MP_STATE_HALTED:
> + case KVM_MP_STATE_AP_RESET_HOLD:
> + case KVM_MP_STATE_INIT_RECEIVED:
> + case KVM_MP_STATE_SIPI_RECEIVED:
> + if (!lapic_in_kernel(vcpu))
> + goto out;
> + break;
> +
> + case KVM_MP_STATE_RUNNABLE:
> + break;
> +
> + default:
> goto out;
> + }
>
> /*
> * KVM_MP_STATE_INIT_RECEIVED means the processor is in
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Best regards,
Maxim Levitsky