From e928e9cb3601ce240189bfea05b67ebd391c85ae Mon Sep 17 00:00:00 2001 From: Michael Ellerman Date: Fri, 20 Mar 2015 20:39:41 +1100 Subject: [PATCH] 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 Signed-off-by: Paul Mackerras Signed-off-by: Alexander Graf --- 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 bc9f6fe44e27..9fa2bf8c3f6f 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 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. diff --git a/arch/powerpc/kvm/book3s_hv_builtin.c b/arch/powerpc/kvm/book3s_hv_builtin.c index 1f083ff8a61a..1954a1c4b1f9 100644 --- a/arch/powerpc/kvm/book3s_hv_builtin.c +++ b/arch/powerpc/kvm/book3s_hv_builtin.c @@ -21,6 +21,7 @@ #include #include #include +#include #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 6cbf1630cb70..0814ca122fcd 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 24bfe401373e..55a4763d6d11 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 80db43944afe..6eb808ff637e 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 f574d7be7631..4b60056776d1 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 -- GitLab