On 03.12.14 03:30, Paul Mackerras wrote: > From: Michael Ellerman <michael@xxxxxxxxxxxxxx> > > Some PowerNV systems include a hardware random-number generator. > This HWRNG is present on POWER7+ and POWER8 chips and is capable of > generating one 64-bit random number every microsecond. The random > numbers are produced by sampling a set of 64 unstable high-frequency > oscillators and are almost completely entropic. > > PAPR defines an H_RANDOM hypercall which guests can use to obtain one > 64-bit random sample from the HWRNG. This adds a real-mode > implementation of the H_RANDOM hypercall. This hypercall was > implemented in real mode because the latency of reading the HWRNG is > generally small compared to the latency of a guest exit and entry for > all the threads in the same virtual core. > > Userspace can detect the presence of the HWRNG and the H_RANDOM > implementation by quering the KVM_CAP_PPC_HWRNG capability. The > H_RANDOM hypercall implementation will only be invoked when the guest > does an H_RANDOM hypercall if userspace first enables the in-kernel > H_RANDOM implementation using the KVM_CAP_PPC_ENABLE_HCALL capability. > > Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx> > Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> This conflicts with the per-cpu cleanups. I've pulled the patch from my queue. Please rebase it once we've got everything merged together and resubmit. Alex -- 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
