linux_dsm_epyc7002/arch/powerpc/include/asm/archrandom.h
Michael Ellerman e928e9cb36 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>
2015-04-21 15:21:29 +02:00

58 lines
1.1 KiB
C

#ifndef _ASM_POWERPC_ARCHRANDOM_H
#define _ASM_POWERPC_ARCHRANDOM_H
#ifdef CONFIG_ARCH_RANDOM
#include <asm/machdep.h>
static inline int arch_get_random_long(unsigned long *v)
{
if (ppc_md.get_random_long)
return ppc_md.get_random_long(v);
return 0;
}
static inline int arch_get_random_int(unsigned int *v)
{
unsigned long val;
int rc;
rc = arch_get_random_long(&val);
if (rc)
*v = val;
return rc;
}
static inline int arch_has_random(void)
{
return !!ppc_md.get_random_long;
}
static inline int arch_get_random_seed_long(unsigned long *v)
{
return 0;
}
static inline int arch_get_random_seed_int(unsigned int *v)
{
return 0;
}
static inline int arch_has_random_seed(void)
{
return 0;
}
#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 */