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| author | Michael Ellerman <michael@ellerman.id.au> | 2015-03-20 20:39:41 +1100 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2015-04-21 15:21:29 +0200 |
| commit | e928e9cb3601ce240189bfea05b67ebd391c85ae (patch) | |
| tree | d76d6501bea8ffe04a448e5a5660d8926f22b3b4 /arch/powerpc/include/asm/archrandom.h | |
| parent | 99342cf8044420eebdf9297ca03a14cb6a7085a1 (diff) | |
| download | lwn-e928e9cb3601ce240189bfea05b67ebd391c85ae.tar.gz lwn-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 'arch/powerpc/include/asm/archrandom.h')
| -rw-r--r-- | arch/powerpc/include/asm/archrandom.h | 11 |
1 files changed, 9 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 */ |