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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 /arch/powerpc/include
parent99342cf8044420eebdf9297ca03a14cb6a7085a1 (diff)
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 'arch/powerpc/include')
-rw-r--r--arch/powerpc/include/asm/archrandom.h11
-rw-r--r--arch/powerpc/include/asm/kvm_ppc.h2
2 files changed, 11 insertions, 2 deletions
diff --git a/arch/powerpc/include/asm/archrandom.h b/arch/powerpc/include/asm/archrandom.h
index bde531103638..0cc6eedc4780 100644
--- a/arch/powerpc/include/asm/archrandom.h
+++ b/arch/powerpc/include/asm/archrandom.h
@@ -30,8 +30,6 @@ static inline int arch_has_random(void)
return !!ppc_md.get_random_long;
}
-int powernv_get_random_long(unsigned long *v);
-
static inline int arch_get_random_seed_long(unsigned long *v)
{
return 0;
@@ -47,4 +45,13 @@ static inline int arch_has_random_seed(void)
#endif /* CONFIG_ARCH_RANDOM */
+#ifdef CONFIG_PPC_POWERNV
+int powernv_hwrng_present(void);
+int powernv_get_random_long(unsigned long *v);
+int powernv_get_random_real_mode(unsigned long *v);
+#else
+static inline int powernv_hwrng_present(void) { return 0; }
+static inline int powernv_get_random_real_mode(unsigned long *v) { return 0; }
+#endif
+
#endif /* _ASM_POWERPC_ARCHRANDOM_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.