From: Michael Ellerman Date: Fri, 20 Mar 2015 09:39:41 +0000 (+1100) Subject: KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation. X-Git-Tag: omap-for-v4.1/fixes-rc1~27^2~1^2~18 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e928e9cb3601ce240189bfea05b67ebd391c85ae;p=pandora-kernel.git KVM: PPC: Book3S HV: Add fast real-mode H_RANDOM implementation. 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 querying 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 Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- Reading git-diff-tree failed