From: Michael Ellerman <mich...@ellerman.id.au>
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 <mich...@ellerman.id.au>
Signed-off-by: Paul Mackerras <pau...@samba.org>
Signed-off-by: Alexander Graf <ag...@suse.de>
---
Documentation/virtual/kvm/api.txt | 17 +++++
arch/powerpc/include/asm/archrandom.h | 11 ++-
arch/powerpc/include/asm/kvm_ppc.h | 2 +
arch/powerpc/kvm/book3s_hv_builtin.c | 15 +++++
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 115 ++++++++++++++++++++++++++++++++
arch/powerpc/kvm/powerpc.c | 3 +
arch/powerpc/platforms/powernv/rng.c | 29 ++++++++
include/uapi/linux/kvm.h | 1 +
8 files changed, 191 insertions(+), 2 deletions(-)
diff --git a/Documentation/virtual/kvm/api.txt
b/Documentation/virtual/kvm/api.txt
index bc9f6fe..9fa2bf8 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3573,3 +3573,20 @@ struct {
@ar - access register number
KVM handlers should exit to userspace with rc = -EREMOTE.
+
+
+8. Other capabilities.
+----------------------
+
+This section lists capabilities that give information about other
+features of the KVM implementation.
+
+8.1 KVM_CAP_PPC_HWRNG
+
+Architectures: ppc
+
+This capability, if KVM_CHECK_EXTENSION indicates that it is
+available, means that that the kernel has an implementation of the
+H_RANDOM hypercall backed by a hardware random-number generator.
+If present, the kernel H_RANDOM handler can be enabled for guest use
+with the KVM_CAP_PPC_ENABLE_HCALL capability.
diff --git a/arch/powerpc/include/asm/archrandom.h
b/arch/powerpc/include/asm/archrandom.h
index bde5311..0cc6eed 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 46bf652..b8475da 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.
diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c
b/arch/powerpc/kvm/book3s_hv_builtin.c
index 1f083ff..1954a1c 100644
--- a/arch/powerpc/kvm/book3s_hv_builtin.c
+++ b/arch/powerpc/kvm/book3s_hv_builtin.c
@@ -21,6 +21,7 @@
#include <asm/cputable.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
+#include <asm/archrandom.h>
#define KVM_CMA_CHUNK_ORDER 18
@@ -169,3 +170,17 @@ int kvmppc_hcall_impl_hv_realmode(unsigned long cmd)
return 0;
}
EXPORT_SYMBOL_GPL(kvmppc_hcall_impl_hv_realmode);
+
+int kvmppc_hwrng_present(void)
+{
+ return powernv_hwrng_present();
+}
+EXPORT_SYMBOL_GPL(kvmppc_hwrng_present);
+
+long kvmppc_h_random(struct kvm_vcpu *vcpu)
+{
+ if (powernv_get_random_real_mode(&vcpu->arch.gpr[4]))
+ return H_SUCCESS;
+
+ return H_HARDWARE;
+}
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 6cbf163..0814ca1 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -1839,6 +1839,121 @@ hcall_real_table:
.long 0 /* 0x12c */
.long 0 /* 0x130 */
.long DOTSYM(kvmppc_h_set_xdabr) - hcall_real_table
+ .long 0 /* 0x138 */
+ .long 0 /* 0x13c */
+ .long 0 /* 0x140 */
+ .long 0 /* 0x144 */
+ .long 0 /* 0x148 */
+ .long 0 /* 0x14c */
+ .long 0 /* 0x150 */
+ .long 0 /* 0x154 */
+ .long 0 /* 0x158 */
+ .long 0 /* 0x15c */
+ .long 0 /* 0x160 */
+ .long 0 /* 0x164 */
+ .long 0 /* 0x168 */
+ .long 0 /* 0x16c */
+ .long 0 /* 0x170 */
+ .long 0 /* 0x174 */
+ .long 0 /* 0x178 */
+ .long 0 /* 0x17c */
+ .long 0 /* 0x180 */
+ .long 0 /* 0x184 */
+ .long 0 /* 0x188 */
+ .long 0 /* 0x18c */
+ .long 0 /* 0x190 */
+ .long 0 /* 0x194 */
+ .long 0 /* 0x198 */
+ .long 0 /* 0x19c */
+ .long 0 /* 0x1a0 */
+ .long 0 /* 0x1a4 */
+ .long 0 /* 0x1a8 */
+ .long 0 /* 0x1ac */
+ .long 0 /* 0x1b0 */
+ .long 0 /* 0x1b4 */
+ .long 0 /* 0x1b8 */
+ .long 0 /* 0x1bc */
+ .long 0 /* 0x1c0 */
+ .long 0 /* 0x1c4 */
+ .long 0 /* 0x1c8 */
+ .long 0 /* 0x1cc */
+ .long 0 /* 0x1d0 */
+ .long 0 /* 0x1d4 */
+ .long 0 /* 0x1d8 */
+ .long 0 /* 0x1dc */
+ .long 0 /* 0x1e0 */
+ .long 0 /* 0x1e4 */
+ .long 0 /* 0x1e8 */
+ .long 0 /* 0x1ec */
+ .long 0 /* 0x1f0 */
+ .long 0 /* 0x1f4 */
+ .long 0 /* 0x1f8 */
+ .long 0 /* 0x1fc */
+ .long 0 /* 0x200 */
+ .long 0 /* 0x204 */
+ .long 0 /* 0x208 */
+ .long 0 /* 0x20c */
+ .long 0 /* 0x210 */
+ .long 0 /* 0x214 */
+ .long 0 /* 0x218 */
+ .long 0 /* 0x21c */
+ .long 0 /* 0x220 */
+ .long 0 /* 0x224 */
+ .long 0 /* 0x228 */
+ .long 0 /* 0x22c */
+ .long 0 /* 0x230 */
+ .long 0 /* 0x234 */
+ .long 0 /* 0x238 */
+ .long 0 /* 0x23c */
+ .long 0 /* 0x240 */
+ .long 0 /* 0x244 */
+ .long 0 /* 0x248 */
+ .long 0 /* 0x24c */
+ .long 0 /* 0x250 */
+ .long 0 /* 0x254 */
+ .long 0 /* 0x258 */
+ .long 0 /* 0x25c */
+ .long 0 /* 0x260 */
+ .long 0 /* 0x264 */
+ .long 0 /* 0x268 */
+ .long 0 /* 0x26c */
+ .long 0 /* 0x270 */
+ .long 0 /* 0x274 */
+ .long 0 /* 0x278 */
+ .long 0 /* 0x27c */
+ .long 0 /* 0x280 */
+ .long 0 /* 0x284 */
+ .long 0 /* 0x288 */
+ .long 0 /* 0x28c */
+ .long 0 /* 0x290 */
+ .long 0 /* 0x294 */
+ .long 0 /* 0x298 */
+ .long 0 /* 0x29c */
+ .long 0 /* 0x2a0 */
+ .long 0 /* 0x2a4 */
+ .long 0 /* 0x2a8 */
+ .long 0 /* 0x2ac */
+ .long 0 /* 0x2b0 */
+ .long 0 /* 0x2b4 */
+ .long 0 /* 0x2b8 */
+ .long 0 /* 0x2bc */
+ .long 0 /* 0x2c0 */
+ .long 0 /* 0x2c4 */
+ .long 0 /* 0x2c8 */
+ .long 0 /* 0x2cc */
+ .long 0 /* 0x2d0 */
+ .long 0 /* 0x2d4 */
+ .long 0 /* 0x2d8 */
+ .long 0 /* 0x2dc */
+ .long 0 /* 0x2e0 */
+ .long 0 /* 0x2e4 */
+ .long 0 /* 0x2e8 */
+ .long 0 /* 0x2ec */
+ .long 0 /* 0x2f0 */
+ .long 0 /* 0x2f4 */
+ .long 0 /* 0x2f8 */
+ .long 0 /* 0x2fc */
+ .long DOTSYM(kvmppc_h_random) - hcall_real_table
.globl hcall_real_table_end
hcall_real_table_end:
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 24bfe40..55a4763 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -529,6 +529,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_PPC_RMA:
r = 0;
break;
+ case KVM_CAP_PPC_HWRNG:
+ r = kvmppc_hwrng_present();
+ break;
#endif
case KVM_CAP_SYNC_MMU:
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
diff --git a/arch/powerpc/platforms/powernv/rng.c
b/arch/powerpc/platforms/powernv/rng.c
index 80db439..6eb808f 100644
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -24,12 +24,22 @@
struct powernv_rng {
void __iomem *regs;
+ void __iomem *regs_real;
unsigned long mask;
};
static DEFINE_PER_CPU(struct powernv_rng *, powernv_rng);
+int powernv_hwrng_present(void)
+{
+ struct powernv_rng *rng;
+
+ rng = get_cpu_var(powernv_rng);
+ put_cpu_var(rng);
+ return rng != NULL;
+}
+
static unsigned long rng_whiten(struct powernv_rng *rng, unsigned long val)
{
unsigned long parity;
@@ -46,6 +56,17 @@ static unsigned long rng_whiten(struct powernv_rng *rng,
unsigned long val)
return val;
}
+int powernv_get_random_real_mode(unsigned long *v)
+{
+ struct powernv_rng *rng;
+
+ rng = raw_cpu_read(powernv_rng);
+
+ *v = rng_whiten(rng, in_rm64(rng->regs_real));
+
+ return 1;
+}
+
int powernv_get_random_long(unsigned long *v)
{
struct powernv_rng *rng;
@@ -80,12 +101,20 @@ static __init void rng_init_per_cpu(struct powernv_rng
*rng,
static __init int rng_create(struct device_node *dn)
{
struct powernv_rng *rng;
+ struct resource res;
unsigned long val;
rng = kzalloc(sizeof(*rng), GFP_KERNEL);
if (!rng)
return -ENOMEM;
+ if (of_address_to_resource(dn, 0, &res)) {
+ kfree(rng);
+ return -ENXIO;
+ }
+
+ rng->regs_real = (void __iomem *)res.start;
+
rng->regs = of_iomap(dn, 0);
if (!rng->regs) {
kfree(rng);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index f574d7b..4b60056 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
--
1.8.1.4
--
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