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authorMichael Ellerman <michael@ellerman.id.au>2015-03-20 20:39:41 +1100
committerAlexander Graf <agraf@suse.de>2015-04-21 15:21:29 +0200
commite928e9cb3601ce240189bfea05b67ebd391c85ae (patch)
treed76d6501bea8ffe04a448e5a5660d8926f22b3b4 /include/uapi
parent99342cf8044420eebdf9297ca03a14cb6a7085a1 (diff)
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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 <michael@ellerman.id.au> Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'include/uapi')
-rw-r--r--include/uapi/linux/kvm.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f574d7be7631..4b60056776d1 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -813,6 +813,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_MIPS_MSA 112
#define KVM_CAP_S390_INJECT_IRQ 113
#define KVM_CAP_S390_IRQ_STATE 114
+#define KVM_CAP_PPC_HWRNG 115
#ifdef KVM_CAP_IRQ_ROUTING