On Fri, Sep 19, 2014 at 04:03:25PM -0700, David Matlack wrote: > vcpu ioctls can hang the calling thread if issued while a vcpu is > running. There is a mutex per-vcpu, so thats expected, OK... > If we know ioctl is going to be rejected as invalid anyway, > we can fail before trying to take the vcpu mutex. Consider a valid ioctl that takes the vcpu mutex. If you need immediate access for that valid ioctl, it is necessary to interrupt thread which KVM_RUN ioctl executes. So knowledge of whether KVM_RUN is being executed is expected in userspace (either that or ask the KVM_RUN thread to run the ioctl for you, as qemu does). Can't see why having different behaviour for valid/invalid ioctls is a good thing. > This patch does not change functionality, it just makes invalid ioctls > fail faster. Should not be executing vcpu ioctls without interrupt KVM_RUN in the first place. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
