| Message ID | 3e019617640d1b07d0ab1c9a91455957c201d4cd.1406177531.git.luto@amacapital.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Il 24/07/2014 06:57, Andy Lutomirski ha scritto: > This adds a simple interface to allow a guest to request 64 bits of > host nonblocking entropy. This is independent of virtio-rng for a > couple of reasons: > > - It's intended to be usable during early boot, when a trivial > synchronous interface is needed. > > - virtio-rng gives blocking entropy, and making guest boot wait for > the host's /dev/random will cause problems. > > MSR_KVM_GET_RNG_SEED is intended to provide 64 bits of best-effort > cryptographically secure data for use as a seed. It provides no > guarantee that the result contains any actual entropy. > > Signed-off-by: Andy Lutomirski <luto@amacapital.net> > --- > Documentation/virtual/kvm/cpuid.txt | 3 +++ > arch/x86/include/uapi/asm/kvm_para.h | 2 ++ > arch/x86/kvm/cpuid.c | 3 ++- > arch/x86/kvm/x86.c | 4 ++++ > 4 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt > index 3c65feb..0ab043b 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -54,6 +54,9 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit > || || before enabling paravirtualized > || || spinlock support. > ------------------------------------------------------------------------------ > +KVM_FEATURE_GET_RNG_SEED || 8 || host provides rng seed data via > + || || MSR_KVM_GET_RNG_SEED. > +------------------------------------------------------------------------------ > KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side > || || per-cpu warps are expected in > || || kvmclock. > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h > index 94dc8ca..e2eaf93 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -24,6 +24,7 @@ > #define KVM_FEATURE_STEAL_TIME 5 > #define KVM_FEATURE_PV_EOI 6 > #define KVM_FEATURE_PV_UNHALT 7 > +#define KVM_FEATURE_GET_RNG_SEED 8 > > /* The last 8 bits are used to indicate how to interpret the flags field > * in pvclock structure. If no bits are set, all flags are ignored. > @@ -40,6 +41,7 @@ > #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 > #define MSR_KVM_STEAL_TIME 0x4b564d03 > #define MSR_KVM_PV_EOI_EN 0x4b564d04 > +#define MSR_KVM_GET_RNG_SEED 0x4b564d05 > > struct kvm_steal_time { > __u64 steal; > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 38a0afe..40d6763 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -479,7 +479,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > (1 << KVM_FEATURE_ASYNC_PF) | > (1 << KVM_FEATURE_PV_EOI) | > (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | > - (1 << KVM_FEATURE_PV_UNHALT); > + (1 << KVM_FEATURE_PV_UNHALT) | > + (1 << KVM_FEATURE_GET_RNG_SEED); > > if (sched_info_on()) > entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index f644933..4e81853 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -48,6 +48,7 @@ > #include <linux/pci.h> > #include <linux/timekeeper_internal.h> > #include <linux/pvclock_gtod.h> > +#include <linux/random.h> > #include <trace/events/kvm.h> > > #define CREATE_TRACE_POINTS > @@ -2480,6 +2481,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) > case MSR_KVM_PV_EOI_EN: > data = vcpu->arch.pv_eoi.msr_val; > break; > + case MSR_KVM_GET_RNG_SEED: > + get_random_bytes(&data, sizeof(data)); > + break; > case MSR_IA32_P5_MC_ADDR: > case MSR_IA32_P5_MC_TYPE: > case MSR_IA32_MCG_CAP: > Acked-by: Paolo Bonzini <pbonzini@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt index 3c65feb..0ab043b 100644 --- a/Documentation/virtual/kvm/cpuid.txt +++ b/Documentation/virtual/kvm/cpuid.txt @@ -54,6 +54,9 @@ KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit || || before enabling paravirtualized || || spinlock support. ------------------------------------------------------------------------------ +KVM_FEATURE_GET_RNG_SEED || 8 || host provides rng seed data via + || || MSR_KVM_GET_RNG_SEED. +------------------------------------------------------------------------------ KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side || || per-cpu warps are expected in || || kvmclock. diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h index 94dc8ca..e2eaf93 100644 --- a/arch/x86/include/uapi/asm/kvm_para.h +++ b/arch/x86/include/uapi/asm/kvm_para.h @@ -24,6 +24,7 @@ #define KVM_FEATURE_STEAL_TIME 5 #define KVM_FEATURE_PV_EOI 6 #define KVM_FEATURE_PV_UNHALT 7 +#define KVM_FEATURE_GET_RNG_SEED 8 /* The last 8 bits are used to indicate how to interpret the flags field * in pvclock structure. If no bits are set, all flags are ignored. @@ -40,6 +41,7 @@ #define MSR_KVM_ASYNC_PF_EN 0x4b564d02 #define MSR_KVM_STEAL_TIME 0x4b564d03 #define MSR_KVM_PV_EOI_EN 0x4b564d04 +#define MSR_KVM_GET_RNG_SEED 0x4b564d05 struct kvm_steal_time { __u64 steal; diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 38a0afe..40d6763 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -479,7 +479,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, (1 << KVM_FEATURE_ASYNC_PF) | (1 << KVM_FEATURE_PV_EOI) | (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) | - (1 << KVM_FEATURE_PV_UNHALT); + (1 << KVM_FEATURE_PV_UNHALT) | + (1 << KVM_FEATURE_GET_RNG_SEED); if (sched_info_on()) entry->eax |= (1 << KVM_FEATURE_STEAL_TIME); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index f644933..4e81853 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -48,6 +48,7 @@ #include <linux/pci.h> #include <linux/timekeeper_internal.h> #include <linux/pvclock_gtod.h> +#include <linux/random.h> #include <trace/events/kvm.h> #define CREATE_TRACE_POINTS @@ -2480,6 +2481,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata) case MSR_KVM_PV_EOI_EN: data = vcpu->arch.pv_eoi.msr_val; break; + case MSR_KVM_GET_RNG_SEED: + get_random_bytes(&data, sizeof(data)); + break; case MSR_IA32_P5_MC_ADDR: case MSR_IA32_P5_MC_TYPE: case MSR_IA32_MCG_CAP:
This adds a simple interface to allow a guest to request 64 bits of host nonblocking entropy. This is independent of virtio-rng for a couple of reasons: - It's intended to be usable during early boot, when a trivial synchronous interface is needed. - virtio-rng gives blocking entropy, and making guest boot wait for the host's /dev/random will cause problems. MSR_KVM_GET_RNG_SEED is intended to provide 64 bits of best-effort cryptographically secure data for use as a seed. It provides no guarantee that the result contains any actual entropy. Signed-off-by: Andy Lutomirski <luto@amacapital.net> --- Documentation/virtual/kvm/cpuid.txt | 3 +++ arch/x86/include/uapi/asm/kvm_para.h | 2 ++ arch/x86/kvm/cpuid.c | 3 ++- arch/x86/kvm/x86.c | 4 ++++ 4 files changed, 11 insertions(+), 1 deletion(-)