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| author | Michael Ellerman <michael@ellerman.id.au> | 2015-03-20 10:39:41 +0100 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2015-04-21 15:21:29 +0200 |
| commit | e928e9cb3601ce240189bfea05b67ebd391c85ae (patch) | |
| tree | d76d6501bea8ffe04a448e5a5660d8926f22b3b4 /include | |
| parent | kvmppc: Implement H_LOGICAL_CI_{LOAD,STORE} in KVM (diff) | |
| download | linux-e928e9cb3601ce240189bfea05b67ebd391c85ae.tar.xz linux-e928e9cb3601ce240189bfea05b67ebd391c85ae.zip | |
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')
| -rw-r--r-- | include/uapi/linux/kvm.h | 1 |
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 |