From: Nicușor Cîțu <[email protected]> This commit also ensures that only the userspace or the introspection tool can control the #BP interception exclusively at one time.
Signed-off-by: Nicușor Cîțu <[email protected]> Signed-off-by: Adalbert Lazăr <[email protected]> --- arch/x86/include/asm/kvm_host.h | 3 + arch/x86/include/asm/kvmi_host.h | 22 +++++++ arch/x86/kvm/kvmi.c | 99 ++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c | 5 ++ virt/kvm/introspection/kvmi.c | 27 ++++++++- virt/kvm/introspection/kvmi_int.h | 6 +- 6 files changed, 157 insertions(+), 5 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index c2176012676d..5f3b6f20718f 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -832,6 +832,9 @@ struct kvm_vcpu_arch { /* #PF translated error code from EPT/NPT exit reason */ u64 error_code; + + /* Control the interception for KVM Introspection */ + struct kvmi_interception *kvmi; }; struct kvm_lpage_info { diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h index 360a57dd9019..c8b793915b84 100644 --- a/arch/x86/include/asm/kvmi_host.h +++ b/arch/x86/include/asm/kvmi_host.h @@ -2,10 +2,32 @@ #ifndef _ASM_X86_KVMI_HOST_H #define _ASM_X86_KVMI_HOST_H +struct kvmi_monitor_interception { + bool kvmi_intercepted; + bool kvm_intercepted; + bool (*monitor_fct)(struct kvm_vcpu *vcpu, bool enable); +}; + +struct kvmi_interception { + bool restore_interception; + struct kvmi_monitor_interception breakpoint; +}; + struct kvm_vcpu_arch_introspection { }; struct kvm_arch_introspection { }; +#ifdef CONFIG_KVM_INTROSPECTION + +bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg); + +#else /* CONFIG_KVM_INTROSPECTION */ + +static inline bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg) + { return false; } + +#endif /* CONFIG_KVM_INTROSPECTION */ + #endif /* _ASM_X86_KVMI_HOST_H */ diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c index 92314341b3a9..74fca566a44a 100644 --- a/arch/x86/kvm/kvmi.c +++ b/arch/x86/kvm/kvmi.c @@ -242,18 +242,71 @@ void kvmi_arch_hypercall_event(struct kvm_vcpu *vcpu) } } +/* + * Returns true if one side (kvm or kvmi) tries to enable/disable the breakpoint + * interception while the other side is still tracking it. + */ +bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg) +{ + struct kvmi_interception *arch_vcpui = READ_ONCE(vcpu->arch.kvmi); + u32 bp_mask = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP; + bool enable = false; + + if ((dbg & bp_mask) == bp_mask) + enable = true; + + return (arch_vcpui && arch_vcpui->breakpoint.monitor_fct(vcpu, enable)); +} +EXPORT_SYMBOL(kvmi_monitor_bp_intercept); + +static bool monitor_bp_fct_kvmi(struct kvm_vcpu *vcpu, bool enable) +{ + if (enable) { + if (kvm_x86_ops->bp_intercepted(vcpu)) + return true; + } else if (!vcpu->arch.kvmi->breakpoint.kvmi_intercepted) + return true; + + vcpu->arch.kvmi->breakpoint.kvmi_intercepted = enable; + + return false; +} + +static bool monitor_bp_fct_kvm(struct kvm_vcpu *vcpu, bool enable) +{ + if (enable) { + if (kvm_x86_ops->bp_intercepted(vcpu)) + return true; + } else if (!vcpu->arch.kvmi->breakpoint.kvm_intercepted) + return true; + + vcpu->arch.kvmi->breakpoint.kvm_intercepted = enable; + + return false; +} + static int kvmi_control_bp_intercept(struct kvm_vcpu *vcpu, bool enable) { struct kvm_guest_debug dbg = {}; int err = 0; + vcpu->arch.kvmi->breakpoint.monitor_fct = monitor_bp_fct_kvmi; if (enable) dbg.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP; err = kvm_arch_vcpu_set_guest_debug(vcpu, &dbg); + vcpu->arch.kvmi->breakpoint.monitor_fct = monitor_bp_fct_kvm; return err; } +static void kvmi_arch_disable_bp_intercept(struct kvm_vcpu *vcpu) +{ + kvmi_control_bp_intercept(vcpu, false); + + vcpu->arch.kvmi->breakpoint.kvmi_intercepted = false; + vcpu->arch.kvmi->breakpoint.kvm_intercepted = false; +} + int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, unsigned int event_id, bool enable) { @@ -290,6 +343,50 @@ void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len) } } -void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu) +bool kvmi_arch_restore_interception(struct kvm_vcpu *vcpu) { + struct kvmi_interception *arch_vcpui = vcpu->arch.kvmi; + + if (!arch_vcpui || !arch_vcpui->restore_interception) + return false; + + kvmi_arch_disable_bp_intercept(vcpu); + + return true; +} + +bool kvmi_arch_vcpu_alloc(struct kvm_vcpu *vcpu) +{ + struct kvmi_interception *arch_vcpui; + + arch_vcpui = kzalloc(sizeof(*arch_vcpui), GFP_KERNEL); + if (!arch_vcpui) + return false; + + arch_vcpui->breakpoint.monitor_fct = monitor_bp_fct_kvm; + + /* pair with kvmi_monitor_bp_intercept() */ + smp_wmb(); + WRITE_ONCE(vcpu->arch.kvmi, arch_vcpui); + + return true; +} + +void kvmi_arch_vcpu_free(struct kvm_vcpu *vcpu) +{ + kfree(vcpu->arch.kvmi); + WRITE_ONCE(vcpu->arch.kvmi, NULL); +} + +bool kvmi_arch_vcpu_introspected(struct kvm_vcpu *vcpu) +{ + return !!READ_ONCE(vcpu->arch.kvmi); +} + +void kvmi_arch_request_restore_interception(struct kvm_vcpu *vcpu) +{ + struct kvmi_interception *arch_vcpui = READ_ONCE(vcpu->arch.kvmi); + + if (arch_vcpui) + arch_vcpui->restore_interception = true; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bad66420f054..31273c4c7f8d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -9169,6 +9169,11 @@ int kvm_arch_vcpu_set_guest_debug(struct kvm_vcpu *vcpu, kvm_queue_exception(vcpu, BP_VECTOR); } + if (kvmi_monitor_bp_intercept(vcpu, dbg->control)) { + r = -EBUSY; + goto out; + } + /* * Read rflags as long as potentially injected trace flags are still * filtered out. diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c index 32516cc70928..7ea0512bc580 100644 --- a/virt/kvm/introspection/kvmi.c +++ b/virt/kvm/introspection/kvmi.c @@ -167,7 +167,7 @@ static bool alloc_vcpui(struct kvm_vcpu *vcpu) vcpu->kvmi = vcpui; - return true; + return kvmi_arch_vcpu_alloc(vcpu); } static int create_vcpui(struct kvm_vcpu *vcpu) @@ -200,6 +200,7 @@ static void free_vcpui(struct kvm_vcpu *vcpu) kfree(vcpui); vcpu->kvmi = NULL; + kvmi_arch_request_restore_interception(vcpu); kvmi_make_request(vcpu, false); } @@ -219,6 +220,7 @@ void kvmi_vcpu_uninit(struct kvm_vcpu *vcpu) { mutex_lock(&vcpu->kvm->kvmi_lock); free_vcpui(vcpu); + kvmi_arch_vcpu_free(vcpu); mutex_unlock(&vcpu->kvm->kvmi_lock); } @@ -358,6 +360,21 @@ static int kvmi_recv_thread(void *arg) return 0; } +static bool ready_to_hook(struct kvm *kvm) +{ + struct kvm_vcpu *vcpu; + int i; + + if (kvm->kvmi) + return false; + + kvm_for_each_vcpu(i, vcpu, kvm) + if (kvmi_arch_vcpu_introspected(vcpu)) + return false; + + return true; +} + int kvmi_hook(struct kvm *kvm, const struct kvm_introspection_hook *hook) { struct kvm_introspection *kvmi; @@ -365,7 +382,7 @@ int kvmi_hook(struct kvm *kvm, const struct kvm_introspection_hook *hook) mutex_lock(&kvm->kvmi_lock); - if (kvm->kvmi) { + if (!ready_to_hook(kvm)) { err = -EEXIST; goto out; } @@ -806,7 +823,11 @@ void kvmi_handle_requests(struct kvm_vcpu *vcpu) kvmi_put(vcpu->kvm); out: - kvmi_arch_restore_interception(vcpu); + if (kvmi_arch_restore_interception(vcpu)) { + mutex_lock(&vcpu->kvm->kvmi_lock); + kvmi_arch_vcpu_free(vcpu); + mutex_unlock(&vcpu->kvm->kvmi_lock); + } } int kvmi_cmd_vcpu_pause(struct kvm_vcpu *vcpu, bool wait) diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h index 0fc622b2c96d..7024bfa3df61 100644 --- a/virt/kvm/introspection/kvmi_int.h +++ b/virt/kvm/introspection/kvmi_int.h @@ -65,7 +65,11 @@ int kvmi_cmd_vcpu_set_registers(struct kvm_vcpu *vcpu, const struct kvm_regs *regs); /* arch */ -void kvmi_arch_restore_interception(struct kvm_vcpu *vcpu); +bool kvmi_arch_vcpu_alloc(struct kvm_vcpu *vcpu); +void kvmi_arch_vcpu_free(struct kvm_vcpu *vcpu); +bool kvmi_arch_vcpu_introspected(struct kvm_vcpu *vcpu); +bool kvmi_arch_restore_interception(struct kvm_vcpu *vcpu); +void kvmi_arch_request_restore_interception(struct kvm_vcpu *vcpu); int kvmi_arch_cmd_vcpu_get_info(struct kvm_vcpu *vcpu, struct kvmi_vcpu_get_info_reply *rpl); void kvmi_arch_setup_event(struct kvm_vcpu *vcpu, struct kvmi_event *ev); _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
