From e928e9cb3601ce240189bfea05b67ebd391c85ae Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 20 Mar 2015 20:39:41 +1100 Subject: 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 --- arch/powerpc/include/asm/kvm_ppc.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/powerpc/include/asm/kvm_ppc.h') diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h index 46bf652c9169..b8475daad884 100644 --- a/arch/powerpc/include/asm/kvm_ppc.h +++ b/arch/powerpc/include/asm/kvm_ppc.h @@ -302,6 +302,8 @@ static inline bool is_kvmppc_hv_enabled(struct kvm *kvm) return kvm->arch.kvm_ops == kvmppc_hv_ops; } +extern int kvmppc_hwrng_present(void); + /* * Cuts out inst bits with ordering according to spec. * That means the leftmost bit is zero. All given bits are included. -- cgit