From: Michael Ellerman <michael@xxxxxxxxxxxxxx>
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 quering 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@xxxxxxxxxxxxxx>
Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx>
---
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 b112efc..ce10b48 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3248,3 +3248,20 @@ All other orders will be handled completely in user space.
Only privileged operation exceptions will be checked for in the kernel (or even
in the hardware prior to interception). If this capability is not enabled, the
old way of handling SIGP orders is used (partially in kernel and user space).
+
+
+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 27c0fac..c645cf6 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 8055706..896ec84 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -760,6 +760,7 @@ struct kvm_ppc_smmu_info {
#define KVM_CAP_PPC_ENABLE_HCALL 104
#define KVM_CAP_CHECK_EXTENSION_VM 105
#define KVM_CAP_S390_USER_SIGP 106
+#define KVM_CAP_PPC_HWRNG 107
#ifdef KVM_CAP_IRQ_ROUTING
--
2.1.4
--
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