Re: [PATCH v3 1/6] KVM: x86: do not allow re-enabling quirks

[Yan Zhao]

LGTM.

On Tue, Mar 04, 2025 at 01:06:42AM -0500, Paolo Bonzini wrote:
> Allowing arbitrary re-enabling of quirks puts a limit on what the
> quirks themselves can do, since you cannot assume that the quirk
> prevents a particular state.  More important, it also prevents
> KVM from disabling a quirk at VM creation time, because userspace
> can always go back and re-enable that.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> ---
>  arch/x86/kvm/x86.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 856ceeb4fb35..35d03fcdb8e9 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6525,7 +6525,7 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
>  			break;
>  		fallthrough;
>  	case KVM_CAP_DISABLE_QUIRKS:
> -		kvm->arch.disabled_quirks = cap->args[0];
> +		kvm->arch.disabled_quirks |= cap->args[0];
>  		r = 0;
>  		break;
>  	case KVM_CAP_SPLIT_IRQCHIP: {
> -- 
> 2.43.5
> 
>