Daniel P. Berrangé: > On Fri, Aug 10, 2018 at 08:33:00PM +0000, procmem wrote: >> Hello. I'm a distro maintainer and was wondering about the efficacy of >> entropy daemons like haveged and jitterentropyd in qemu-kvm. One of the >> authors of haveged [0] pointed out if the hardware cycles counter is >> emulated and deterministic, and thus predictible. He therefore does not >> recommend using HAVEGE on those systems. Is this the case with KVM's >> counters? >> >> PS. I will be setting VM CPU settings to host-passthrough. > > Hardware from circa 2011 onwards has RDRAND support, and with host-passthrough > this will be available to the guest. The rngd daemon, running in the guest, > can use this as a source to feed the kernel entropy. > > In addition QEMU has support for virtio-rng which can pull entropy from > /dev/urandom on the host, and feed it into the guest, where again rngd can > give it to the kernel. > > So why do you need to consider haveged / jitterentropyd at all with QEMU ? > It should suffice to just enable virtio-rng in the host and run rngd in > all guests. If the host has RDRAND, that's an extra bonus. > > haveged / jitterentropyd should only be needed on other non-QEMU hypervisors > which don't support something equiv to virtio-rng, and are on hardware that > is too old for RDRAND. > > Regards, > Daniel > Makes sense. Thanks for your answer. _______________________________________________ libvirt-users mailing list libvirt-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvirt-users
