From: Nicușor Cîțu <[email protected]> This event is sent when IDTR, GDTR, LDTR or TR are accessed.
These could be used to implement a tiny agent which runs in the context of an introspected guest and uses virtualized exceptions (#VE) and alternate EPT views (VMFUNC #0) to filter converted VMEXITS. The events of interested will be suppressed (after some appropriate guest-side handling) while the rest will be sent to the introspector via a VMCALL. Signed-off-by: Nicușor Cîțu <[email protected]> Co-developed-by: Adalbert Lazăr <[email protected]> Signed-off-by: Adalbert Lazăr <[email protected]> --- Documentation/virt/kvm/kvmi.rst | 39 ++++++++++++ arch/x86/include/asm/kvmi_host.h | 3 + arch/x86/include/uapi/asm/kvmi.h | 11 ++++ arch/x86/kvm/kvmi.c | 57 ++++++++++++++++++ arch/x86/kvm/svm.c | 45 ++++++++++++++ arch/x86/kvm/vmx/vmx.c | 37 +++++++++++- include/uapi/linux/kvmi.h | 1 + .../testing/selftests/kvm/x86_64/kvmi_test.c | 60 +++++++++++++++++++ virt/kvm/introspection/kvmi_int.h | 2 + virt/kvm/introspection/kvmi_msg.c | 17 ++++++ 10 files changed, 270 insertions(+), 2 deletions(-) diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst index ae8e242c4721..0a0e5305a0af 100644 --- a/Documentation/virt/kvm/kvmi.rst +++ b/Documentation/virt/kvm/kvmi.rst @@ -532,6 +532,7 @@ the following events:: KVMI_EVENT_BREAKPOINT KVMI_EVENT_CR + KVMI_EVENT_DESCRIPTOR KVMI_EVENT_HYPERCALL KVMI_EVENT_TRAP KVMI_EVENT_XSETBV @@ -1088,3 +1089,41 @@ to be changed and the introspection has been enabled for this event (see *KVMI_VCPU_CONTROL_EVENTS*). ``kvmi_event`` is sent to the introspection tool. + +8. KVMI_EVENT_DESCRIPTOR +------------------------ + +:Architecture: x86 +:Versions: >= 1 +:Actions: CONTINUE, RETRY, CRASH +:Parameters: + +:: + + struct kvmi_event; + struct kvmi_event_descriptor { + __u8 descriptor; + __u8 write; + __u8 padding[6]; + }; + +:Returns: + +:: + + struct kvmi_vcpu_hdr; + struct kvmi_event_reply; + +This event is sent when a descriptor table register is accessed and the +introspection has been enabled for this event (see **KVMI_VCPU_CONTROL_EVENTS**). + +``kvmi_event`` and ``kvmi_event_descriptor`` are sent to the introspection tool. + +``descriptor`` can be one of:: + + KVMI_DESC_IDTR + KVMI_DESC_GDTR + KVMI_DESC_LDTR + KVMI_DESC_TR + +``write`` is 1 if the descriptor was written, 0 otherwise. diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h index b3fa950362db..8f9e6bd2953a 100644 --- a/arch/x86/include/asm/kvmi_host.h +++ b/arch/x86/include/asm/kvmi_host.h @@ -31,6 +31,7 @@ bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu); bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable); void kvmi_xsetbv_event(struct kvm_vcpu *vcpu); +bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write); #else /* CONFIG_KVM_INTROSPECTION */ @@ -43,6 +44,8 @@ static inline bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu) { return false; } static inline bool kvmi_monitor_cr3w_intercept(struct kvm_vcpu *vcpu, bool enable) { return false; } static inline void kvmi_xsetbv_event(struct kvm_vcpu *vcpu) { } +static inline bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, + u8 write) { return true; } #endif /* CONFIG_KVM_INTROSPECTION */ diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h index 1dc3fc02d3ec..6f411b9ba449 100644 --- a/arch/x86/include/uapi/asm/kvmi.h +++ b/arch/x86/include/uapi/asm/kvmi.h @@ -110,4 +110,15 @@ struct kvmi_vcpu_get_mtrr_type_reply { __u8 padding[7]; }; +#define KVMI_DESC_IDTR 1 +#define KVMI_DESC_GDTR 2 +#define KVMI_DESC_LDTR 3 +#define KVMI_DESC_TR 4 + +struct kvmi_event_descriptor { + __u8 descriptor; + __u8 write; + __u8 padding[6]; +}; + #endif /* _UAPI_ASM_X86_KVMI_H */ diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c index d3cddd34326b..ed9b45060e2a 100644 --- a/arch/x86/kvm/kvmi.c +++ b/arch/x86/kvm/kvmi.c @@ -311,6 +311,21 @@ static void kvmi_arch_disable_cr3w_intercept(struct kvm_vcpu *vcpu) vcpu->arch.kvmi->cr3w.kvm_intercepted = false; } +static int kvmi_control_desc_intercept(struct kvm_vcpu *vcpu, bool enable) +{ + if (!kvm_x86_ops->umip_emulated()) + return -KVM_EOPNOTSUPP; + + kvm_x86_ops->control_desc_intercept(vcpu, enable); + + return 0; +} + +static void kvmi_arch_disable_desc_intercept(struct kvm_vcpu *vcpu) +{ + kvmi_control_desc_intercept(vcpu, false); +} + int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, unsigned int event_id, bool enable) { @@ -320,6 +335,9 @@ int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, case KVMI_EVENT_BREAKPOINT: err = kvmi_control_bp_intercept(vcpu, enable); break; + case KVMI_EVENT_DESCRIPTOR: + err = kvmi_control_desc_intercept(vcpu, enable); + break; default: break; } @@ -356,6 +374,7 @@ bool kvmi_arch_restore_interception(struct kvm_vcpu *vcpu) kvmi_arch_disable_bp_intercept(vcpu); kvmi_arch_disable_cr3w_intercept(vcpu); + kvmi_arch_disable_desc_intercept(vcpu); return true; } @@ -644,3 +663,41 @@ int kvmi_arch_cmd_vcpu_get_mtrr_type(struct kvm_vcpu *vcpu, u64 gpa, u8 *type) return 0; } + +static bool __kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, + u8 write) +{ + bool ret = false; + u32 action; + + action = kvmi_msg_send_descriptor(vcpu, descriptor, write); + switch (action) { + case KVMI_EVENT_ACTION_CONTINUE: + ret = true; + break; + case KVMI_EVENT_ACTION_RETRY: + break; + default: + kvmi_handle_common_event_actions(vcpu->kvm, action, "DESC"); + } + + return ret; +} + +bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write) +{ + struct kvm_introspection *kvmi; + bool ret = true; + + kvmi = kvmi_get(vcpu->kvm); + if (!kvmi) + return true; + + if (is_event_enabled(vcpu, KVMI_EVENT_DESCRIPTOR)) + ret = __kvmi_descriptor_event(vcpu, descriptor, write); + + kvmi_put(vcpu->kvm); + + return ret; +} +EXPORT_SYMBOL(kvmi_descriptor_event); diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 909308711bb7..988eb6937515 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4808,6 +4808,41 @@ static int avic_unaccelerated_access_interception(struct vcpu_svm *svm) return ret; } +#ifdef CONFIG_KVM_INTROSPECTION +static int descriptor_access_interception(struct vcpu_svm *svm) +{ + struct kvm_vcpu *vcpu = &svm->vcpu; + struct vmcb_control_area *c = &svm->vmcb->control; + + switch (c->exit_code) { + case SVM_EXIT_IDTR_READ: + case SVM_EXIT_IDTR_WRITE: + kvmi_descriptor_event(vcpu, KVMI_DESC_IDTR, + c->exit_code == SVM_EXIT_IDTR_WRITE); + break; + case SVM_EXIT_GDTR_READ: + case SVM_EXIT_GDTR_WRITE: + kvmi_descriptor_event(vcpu, KVMI_DESC_GDTR, + c->exit_code == SVM_EXIT_GDTR_WRITE); + break; + case SVM_EXIT_LDTR_READ: + case SVM_EXIT_LDTR_WRITE: + kvmi_descriptor_event(vcpu, KVMI_DESC_LDTR, + c->exit_code == SVM_EXIT_LDTR_WRITE); + break; + case SVM_EXIT_TR_READ: + case SVM_EXIT_TR_WRITE: + kvmi_descriptor_event(vcpu, KVMI_DESC_TR, + c->exit_code == SVM_EXIT_TR_WRITE); + break; + default: + break; + } + + return kvm_emulate_instruction(vcpu, 0); +} +#endif /* CONFIG_KVM_INTROSPECTION */ + static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { [SVM_EXIT_READ_CR0] = cr_interception, [SVM_EXIT_READ_CR3] = cr_interception, @@ -4874,6 +4909,16 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = { [SVM_EXIT_RSM] = rsm_interception, [SVM_EXIT_AVIC_INCOMPLETE_IPI] = avic_incomplete_ipi_interception, [SVM_EXIT_AVIC_UNACCELERATED_ACCESS] = avic_unaccelerated_access_interception, +#ifdef CONFIG_KVM_INTROSPECTION + [SVM_EXIT_IDTR_READ] = descriptor_access_interception, + [SVM_EXIT_GDTR_READ] = descriptor_access_interception, + [SVM_EXIT_LDTR_READ] = descriptor_access_interception, + [SVM_EXIT_TR_READ] = descriptor_access_interception, + [SVM_EXIT_IDTR_WRITE] = descriptor_access_interception, + [SVM_EXIT_GDTR_WRITE] = descriptor_access_interception, + [SVM_EXIT_LDTR_WRITE] = descriptor_access_interception, + [SVM_EXIT_TR_WRITE] = descriptor_access_interception, +#endif /* CONFIG_KVM_INTROSPECTION */ }; static void dump_vmcb(struct kvm_vcpu *vcpu) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 157dfc3f756a..68986f600f98 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -3070,11 +3070,11 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) if (!boot_cpu_has(X86_FEATURE_UMIP) && vmx_umip_emulated()) { if (cr4 & X86_CR4_UMIP) { - secondary_exec_controls_setbit(vmx, SECONDARY_EXEC_DESC); + vmx_control_desc_intercept(vcpu, true); hw_cr4 &= ~X86_CR4_UMIP; } else if (!is_guest_mode(vcpu) || !nested_cpu_has2(get_vmcs12(vcpu), SECONDARY_EXEC_DESC)) { - secondary_exec_controls_clearbit(vmx, SECONDARY_EXEC_DESC); + vmx_control_desc_intercept(vcpu, false); } } @@ -4831,7 +4831,40 @@ static int handle_set_cr4(struct kvm_vcpu *vcpu, unsigned long val) static int handle_desc(struct kvm_vcpu *vcpu) { +#ifdef CONFIG_KVM_INTROSPECTION + struct vcpu_vmx *vmx = to_vmx(vcpu); + u32 exit_reason = vmx->exit_reason; + u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO); + u8 store = (vmx_instruction_info >> 29) & 0x1; + u8 descriptor = 0; + + if (exit_reason == EXIT_REASON_GDTR_IDTR) { + if ((vmx_instruction_info >> 28) & 0x1) + descriptor = KVMI_DESC_IDTR; + else + descriptor = KVMI_DESC_GDTR; + } else { + if ((vmx_instruction_info >> 28) & 0x1) + descriptor = KVMI_DESC_TR; + else + descriptor = KVMI_DESC_LDTR; + } + + /* + * For now, this function returns false only when the guest + * is ungracefully stopped (crashed) or the current instruction + * is skipped by the introspection tool. + */ + if (!kvmi_descriptor_event(vcpu, descriptor, store)) + return 1; + + /* + * We are here because X86_CR4_UMIP was set or + * KVMI enabled the interception. + */ +#else WARN_ON(!(vcpu->arch.cr4 & X86_CR4_UMIP)); +#endif /* CONFIG_KVM_INTROSPECTION */ return kvm_emulate_instruction(vcpu, 0); } diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h index 5e911ca7a636..a8f5dc415e3d 100644 --- a/include/uapi/linux/kvmi.h +++ b/include/uapi/linux/kvmi.h @@ -51,6 +51,7 @@ enum { KVMI_EVENT_CR = 4, KVMI_EVENT_TRAP = 5, KVMI_EVENT_XSETBV = 6, + KVMI_EVENT_DESCRIPTOR = 7, KVMI_NUM_EVENTS }; diff --git a/tools/testing/selftests/kvm/x86_64/kvmi_test.c b/tools/testing/selftests/kvm/x86_64/kvmi_test.c index 600d65922bf4..4308cb995ce3 100644 --- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c +++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c @@ -54,6 +54,7 @@ enum { GUEST_TEST_NOOP = 0, GUEST_TEST_BP, GUEST_TEST_CR, + GUEST_TEST_DESCRIPTOR, GUEST_TEST_HYPERCALL, GUEST_TEST_XSETBV, }; @@ -79,6 +80,14 @@ static void guest_cr_test(void) set_cr4(get_cr4() | X86_CR4_OSXSAVE); } +static void guest_descriptor_test(void) +{ + void *ptr; + + asm volatile("sgdt %0" :: "m"(ptr)); + asm volatile("lgdt %0" :: "m"(ptr)); +} + static void guest_hypercall_test(void) { asm volatile("mov $34, %rax"); @@ -138,6 +147,9 @@ static void guest_code(void) case GUEST_TEST_CR: guest_cr_test(); break; + case GUEST_TEST_DESCRIPTOR: + guest_descriptor_test(); + break; case GUEST_TEST_HYPERCALL: guest_hypercall_test(); break; @@ -1360,6 +1372,53 @@ static void test_cmd_vcpu_get_mtrr_type(struct kvm_vm *vm) DEBUG("mtrr_type: gpa 0x%lx type 0x%x\n", test_gpa, rpl.type); } +static void test_event_descriptor(struct kvm_vm *vm) +{ + struct vcpu_worker_data data = { + .vm = vm, + .vcpu_id = VCPU_ID, + .test_id = GUEST_TEST_DESCRIPTOR, + }; + struct kvmi_msg_hdr hdr; + struct { + struct kvmi_event common; + struct kvmi_event_descriptor desc; + } ev; + struct vcpu_reply rpl = {}; + __u16 event_id = KVMI_EVENT_DESCRIPTOR; + pthread_t vcpu_thread; + + enable_vcpu_event(vm, event_id); + + vcpu_thread = start_vcpu_worker(&data); + + receive_event(&hdr, &ev.common, sizeof(ev), event_id); + + DEBUG("Descriptor event (read), descriptor %u, write %u\n", + ev.desc.descriptor, ev.desc.write); + + TEST_ASSERT(ev.desc.write == 0, + "Received a write descriptor access\n"); + + reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_CONTINUE, + &rpl, sizeof(rpl)); + + receive_event(&hdr, &ev.common, sizeof(ev), event_id); + + DEBUG("Descriptor event (write), descriptor %u, write %u\n", + ev.desc.descriptor, ev.desc.write); + + TEST_ASSERT(ev.desc.write == 1, + "Received a read descriptor access\n"); + + reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_CONTINUE, + &rpl, sizeof(rpl)); + + stop_vcpu_worker(vcpu_thread, &data); + + disable_vcpu_event(vm, event_id); +} + static void test_introspection(struct kvm_vm *vm) { setup_socket(); @@ -1387,6 +1446,7 @@ static void test_introspection(struct kvm_vm *vm) test_event_xsetbv(vm); test_cmd_vcpu_get_xsave(vm); test_cmd_vcpu_get_mtrr_type(vm); + test_event_descriptor(vm); unhook_introspection(vm); } diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h index 1e28355ea4d7..6d2c09a12c49 100644 --- a/virt/kvm/introspection/kvmi_int.h +++ b/virt/kvm/introspection/kvmi_int.h @@ -24,6 +24,7 @@ #define KVMI_KNOWN_VCPU_EVENTS ( \ BIT(KVMI_EVENT_BREAKPOINT) \ | BIT(KVMI_EVENT_CR) \ + | BIT(KVMI_EVENT_DESCRIPTOR) \ | BIT(KVMI_EVENT_HYPERCALL) \ | BIT(KVMI_EVENT_TRAP) \ | BIT(KVMI_EVENT_PAUSE_VCPU) \ @@ -79,6 +80,7 @@ int kvmi_msg_send_unhook(struct kvm_introspection *kvmi); u32 kvmi_msg_send_vcpu_pause(struct kvm_vcpu *vcpu); u32 kvmi_msg_send_hypercall(struct kvm_vcpu *vcpu); u32 kvmi_msg_send_bp(struct kvm_vcpu *vcpu, u64 gpa, u8 insn_len); +u32 kvmi_msg_send_descriptor(struct kvm_vcpu *vcpu, u8 descriptor, u8 write); /* kvmi.c */ void *kvmi_msg_alloc(void); diff --git a/virt/kvm/introspection/kvmi_msg.c b/virt/kvm/introspection/kvmi_msg.c index 6f23bc7517aa..fed483bec936 100644 --- a/virt/kvm/introspection/kvmi_msg.c +++ b/virt/kvm/introspection/kvmi_msg.c @@ -1029,3 +1029,20 @@ void kvmi_xsetbv_event(struct kvm_vcpu *vcpu) kvmi_put(vcpu->kvm); } + +u32 kvmi_msg_send_descriptor(struct kvm_vcpu *vcpu, u8 descriptor, u8 write) +{ + struct kvmi_event_descriptor e; + int err, action; + + memset(&e, 0, sizeof(e)); + e.descriptor = descriptor; + e.write = write; + + err = kvmi_send_event(vcpu, KVMI_EVENT_DESCRIPTOR, &e, sizeof(e), + NULL, 0, &action); + if (err) + return KVMI_EVENT_ACTION_CONTINUE; + + return action; +} _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
