From: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx> Using the KVMI_VCPU_CONTROL_CR command, the introspection tool subscribes to KVMI_EVENT_CR events that will be sent when a control register (CR0, CR3 or CR4) is going to be changed. Signed-off-by: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx> Co-developed-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx> Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx> --- Documentation/virt/kvm/kvmi.rst | 70 +++++++++++ arch/x86/include/asm/kvmi_host.h | 11 ++ arch/x86/include/uapi/asm/kvmi.h | 18 +++ arch/x86/kvm/kvmi.c | 111 ++++++++++++++++++ arch/x86/kvm/vmx/vmx.c | 6 +- arch/x86/kvm/x86.c | 12 +- include/uapi/linux/kvmi.h | 3 + .../testing/selftests/kvm/x86_64/kvmi_test.c | 108 +++++++++++++++++ virt/kvm/introspection/kvmi.c | 1 + virt/kvm/introspection/kvmi_int.h | 7 ++ virt/kvm/introspection/kvmi_msg.c | 18 ++- 11 files changed, 359 insertions(+), 6 deletions(-) diff --git a/Documentation/virt/kvm/kvmi.rst b/Documentation/virt/kvm/kvmi.rst index f760957b27f4..e1f978fc799b 100644 --- a/Documentation/virt/kvm/kvmi.rst +++ b/Documentation/virt/kvm/kvmi.rst @@ -550,6 +550,7 @@ Enables/disables vCPU introspection events. This command can be used with the following events:: KVMI_EVENT_BREAKPOINT + KVMI_EVENT_CR KVMI_EVENT_HYPERCALL When an event is enabled, the introspection tool is notified and @@ -714,6 +715,40 @@ interceptions). By default it is disabled. * -KVM_EINVAL - the padding is not zero * -KVM_EINVAL - 'enabled' is not 1 or 0 +15. KVMI_VCPU_CONTROL_CR +------------------------ + +:Architectures: x86 +:Versions: >= 1 +:Parameters: + +:: + + struct kvmi_vcpu_hdr; + struct kvmi_vcpu_control_cr { + __u8 cr; + __u8 enable; + __u16 padding1; + __u32 padding2; + }; + +:Returns: + +:: + + struct kvmi_error_code + +Enables/disables introspection for a specific control register and must +be used in addition to *KVMI_VCPU_CONTROL_EVENTS* with the *KVMI_EVENT_CR* +ID set. + +:Errors: + +* -KVM_EINVAL - the selected vCPU is invalid +* -KVM_EINVAL - the specified control register is not CR0, CR3 or CR4 +* -KVM_EINVAL - the padding is not zero +* -KVM_EAGAIN - the selected vCPU can't be introspected yet + Events ====== @@ -890,3 +925,38 @@ trying to perform a certain operation (like creating a process). ``kvmi_event`` and the guest physical address are sent to the introspection tool. The *RETRY* action is used by the introspection tool for its own breakpoints. + +5. KVMI_EVENT_CR +---------------- + +:Architectures: x86 +:Versions: >= 1 +:Actions: CONTINUE, CRASH +:Parameters: + +:: + + struct kvmi_event; + struct kvmi_event_cr { + __u8 cr; + __u8 padding[7]; + __u64 old_value; + __u64 new_value; + }; + +:Returns: + +:: + + struct kvmi_vcpu_hdr; + struct kvmi_event_reply; + struct kvmi_event_cr_reply { + __u64 new_val; + }; + +This event is sent when a control register is going to be changed and the +introspection has been enabled for this event and for this specific +register (see **KVMI_VCPU_CONTROL_EVENTS**). + +``kvmi_event``, the control register number, the old value and the new value +are sent to the introspection tool. The *CONTINUE* action will set the ``new_val``. diff --git a/arch/x86/include/asm/kvmi_host.h b/arch/x86/include/asm/kvmi_host.h index 3e85ae4fe5f0..1aff91ef8475 100644 --- a/arch/x86/include/asm/kvmi_host.h +++ b/arch/x86/include/asm/kvmi_host.h @@ -4,6 +4,8 @@ #include <asm/kvmi.h> +#define KVMI_NUM_CR 5 + struct kvmi_monitor_interception { bool kvmi_intercepted; bool kvm_intercepted; @@ -17,6 +19,7 @@ struct kvmi_interception { }; struct kvm_vcpu_arch_introspection { + DECLARE_BITMAP(cr_mask, KVMI_NUM_CR); }; struct kvm_arch_introspection { @@ -25,11 +28,19 @@ struct kvm_arch_introspection { #ifdef CONFIG_KVM_INTROSPECTION bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg); +bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, + unsigned long old_value, unsigned long *new_value); +bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu); #else /* CONFIG_KVM_INTROSPECTION */ static inline bool kvmi_monitor_bp_intercept(struct kvm_vcpu *vcpu, u32 dbg) { return false; } +static inline bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, + unsigned long old_value, + unsigned long *new_value) + { return true; } +static inline bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu) { return false; } #endif /* CONFIG_KVM_INTROSPECTION */ diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h index 1605777256a3..4c59c9fe6b00 100644 --- a/arch/x86/include/uapi/asm/kvmi.h +++ b/arch/x86/include/uapi/asm/kvmi.h @@ -65,4 +65,22 @@ struct kvmi_event_breakpoint { __u8 padding[7]; }; +struct kvmi_vcpu_control_cr { + __u8 cr; + __u8 enable; + __u16 padding1; + __u32 padding2; +}; + +struct kvmi_event_cr { + __u8 cr; + __u8 padding[7]; + __u64 old_value; + __u64 new_value; +}; + +struct kvmi_event_cr_reply { + __u64 new_val; +}; + #endif /* _UAPI_ASM_X86_KVMI_H */ diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c index 89fa158a6535..e72b2ef5b28a 100644 --- a/arch/x86/kvm/kvmi.c +++ b/arch/x86/kvm/kvmi.c @@ -400,3 +400,114 @@ void kvmi_arch_request_interception_cleanup(struct kvm_vcpu *vcpu, arch_vcpui->cleanup = true; } } + +int kvmi_arch_cmd_vcpu_control_cr(struct kvm_vcpu *vcpu, + const struct kvmi_vcpu_control_cr *req) +{ + u32 cr = req->cr; + + if (req->padding1 || req->padding2 || req->enable > 1) + return -KVM_EINVAL; + + switch (cr) { + case 0: + break; + case 3: + kvm_x86_ops.control_cr3_intercept(vcpu, CR_TYPE_W, + req->enable == 1); + break; + case 4: + break; + default: + return -KVM_EINVAL; + } + + if (req->enable) + set_bit(cr, VCPUI(vcpu)->arch.cr_mask); + else + clear_bit(cr, VCPUI(vcpu)->arch.cr_mask); + + return 0; +} + +static u32 kvmi_send_cr(struct kvm_vcpu *vcpu, u32 cr, u64 old_value, + u64 new_value, u64 *ret_value) +{ + struct kvmi_event_cr e; + struct kvmi_event_cr_reply r; + int err, action; + + memset(&e, 0, sizeof(e)); + e.cr = cr; + e.old_value = old_value; + e.new_value = new_value; + + err = kvmi_send_event(vcpu, KVMI_EVENT_CR, &e, sizeof(e), + &r, sizeof(r), &action); + if (err) + return KVMI_EVENT_ACTION_CONTINUE; + + *ret_value = r.new_val; + return action; +} + +static bool __kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, + u64 old_value, unsigned long *new_value) +{ + u64 ret_value = *new_value; + bool ret = false; + u32 action; + + if (!test_bit(cr, VCPUI(vcpu)->arch.cr_mask)) + return true; + + action = kvmi_send_cr(vcpu, cr, old_value, *new_value, &ret_value); + switch (action) { + case KVMI_EVENT_ACTION_CONTINUE: + *new_value = ret_value; + ret = true; + break; + default: + kvmi_handle_common_event_actions(vcpu->kvm, action); + } + + return ret; +} + +bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr, + unsigned long old_value, unsigned long *new_value) +{ + struct kvm_introspection *kvmi; + bool ret = true; + + if (old_value == *new_value) + return true; + + kvmi = kvmi_get(vcpu->kvm); + if (!kvmi) + return true; + + if (is_event_enabled(vcpu, KVMI_EVENT_CR)) + ret = __kvmi_cr_event(vcpu, cr, old_value, new_value); + + kvmi_put(vcpu->kvm); + + return ret; +} + +bool kvmi_cr3_intercepted(struct kvm_vcpu *vcpu) +{ + struct kvm_introspection *kvmi; + bool ret; + + kvmi = kvmi_get(vcpu->kvm); + if (!kvmi) + return false; + + ret = test_bit(3, VCPUI(vcpu)->arch.cr_mask); + + kvmi_put(vcpu->kvm); + + return ret; +} +EXPORT_SYMBOL(kvmi_cr3_intercepted); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 9e1bea74b74c..5d0876420dd9 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5038,7 +5038,8 @@ static int handle_cr(struct kvm_vcpu *vcpu) err = handle_set_cr0(vcpu, val); return kvm_complete_insn_gp(vcpu, err); case 3: - WARN_ON_ONCE(enable_unrestricted_guest); + WARN_ON_ONCE(enable_unrestricted_guest && + !kvmi_cr3_intercepted(vcpu)); err = kvm_set_cr3(vcpu, val); return kvm_complete_insn_gp(vcpu, err); case 4: @@ -5071,7 +5072,8 @@ static int handle_cr(struct kvm_vcpu *vcpu) case 1: /*mov from cr*/ switch (cr) { case 3: - WARN_ON_ONCE(enable_unrestricted_guest); + WARN_ON_ONCE(enable_unrestricted_guest && + !kvmi_cr3_intercepted(vcpu)); val = kvm_read_cr3(vcpu); kvm_register_write(vcpu, reg, val); trace_kvm_cr_read(cr, val); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9c8b7a3c5758..a12aa8e125d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -813,6 +813,9 @@ int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) if (!(cr0 & X86_CR0_PG) && kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE)) return 1; + if (!kvmi_cr_event(vcpu, 0, old_cr0, &cr0)) + return 1; + kvm_x86_ops.set_cr0(vcpu, cr0); if ((cr0 ^ old_cr0) & X86_CR0_PG) { @@ -993,6 +996,9 @@ int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4) return 1; } + if (!kvmi_cr_event(vcpu, 4, old_cr4, &cr4)) + return 1; + if (kvm_x86_ops.set_cr4(vcpu, cr4)) return 1; @@ -1009,6 +1015,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cr4); int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) { + unsigned long old_cr3 = kvm_read_cr3(vcpu); bool skip_tlb_flush = false; #ifdef CONFIG_X86_64 bool pcid_enabled = kvm_read_cr4_bits(vcpu, X86_CR4_PCIDE); @@ -1019,7 +1026,7 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) } #endif - if (cr3 == kvm_read_cr3(vcpu) && !pdptrs_changed(vcpu)) { + if (cr3 == old_cr3 && !pdptrs_changed(vcpu)) { if (!skip_tlb_flush) { kvm_mmu_sync_roots(vcpu); kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); @@ -1034,6 +1041,9 @@ int kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3) !load_pdptrs(vcpu, vcpu->arch.walk_mmu, cr3)) return 1; + if (!kvmi_cr_event(vcpu, 3, old_cr3, &cr3)) + return 1; + kvm_mmu_new_pgd(vcpu, cr3, skip_tlb_flush, skip_tlb_flush); vcpu->arch.cr3 = cr3; kvm_register_mark_available(vcpu, VCPU_EXREG_CR3); diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h index 20bf5bf194a4..e31b474e3496 100644 --- a/include/uapi/linux/kvmi.h +++ b/include/uapi/linux/kvmi.h @@ -34,6 +34,8 @@ enum { KVMI_VM_CONTROL_CLEANUP = 14, + KVMI_VCPU_CONTROL_CR = 15, + KVMI_NUM_MESSAGES }; @@ -42,6 +44,7 @@ enum { KVMI_EVENT_PAUSE_VCPU = 1, KVMI_EVENT_HYPERCALL = 2, KVMI_EVENT_BREAKPOINT = 3, + KVMI_EVENT_CR = 4, 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 d3b7778a64d4..7694fa8fef89 100644 --- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c +++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c @@ -50,6 +50,7 @@ struct vcpu_worker_data { enum { GUEST_TEST_NOOP = 0, GUEST_TEST_BP, + GUEST_TEST_CR, GUEST_TEST_HYPERCALL, }; @@ -73,6 +74,11 @@ static void guest_bp_test(void) asm volatile("int3"); } +static void guest_cr_test(void) +{ + set_cr4(get_cr4() | X86_CR4_OSXSAVE); +} + static void guest_hypercall_test(void) { asm volatile("mov $34, %rax"); @@ -90,6 +96,9 @@ static void guest_code(void) case GUEST_TEST_BP: guest_bp_test(); break; + case GUEST_TEST_CR: + guest_cr_test(); + break; case GUEST_TEST_HYPERCALL: guest_hypercall_test(); break; @@ -1201,6 +1210,104 @@ static void test_cmd_vm_control_cleanup(struct kvm_vm *vm) cmd_vm_control_cleanup(disable, no_padding, 0); } +static void cmd_vcpu_control_cr(struct kvm_vm *vm, __u8 cr, __u8 enable, + __u8 padding, int expected_err) +{ + struct { + struct kvmi_msg_hdr hdr; + struct kvmi_vcpu_hdr vcpu_hdr; + struct kvmi_vcpu_control_cr cmd; + } req = {}; + int r; + + req.cmd.cr = cr; + req.cmd.enable = enable; + req.cmd.padding1 = padding; + req.cmd.padding2 = padding; + + r = do_vcpu0_command(vm, KVMI_VCPU_CONTROL_CR, &req.hdr, sizeof(req), + NULL, 0); + TEST_ASSERT(r == expected_err, + "KVMI_VCPU_CONTROL_CR failed, error %d(%s), expected error %d\n", + -r, kvm_strerror(-r), expected_err); +} + +static void enable_cr_events(struct kvm_vm *vm, __u8 cr) +{ + enable_vcpu_event(vm, KVMI_EVENT_CR); + + cmd_vcpu_control_cr(vm, cr, 1, 0, 0); +} + +static void disable_cr_events(struct kvm_vm *vm, __u8 cr) +{ + cmd_vcpu_control_cr(vm, cr, 0, 0, 0); + + disable_vcpu_event(vm, KVMI_EVENT_CR); +} + +static void test_invalid_vcpu_control_cr(struct kvm_vm *vm) +{ + __u8 enable = 1, enable_inval = 2; + __u8 no_padding = 0, padding = 1; + __u8 cr_inval = 99, cr = 0; + + cmd_vcpu_control_cr(vm, cr, enable_inval, no_padding, -KVM_EINVAL); + cmd_vcpu_control_cr(vm, cr, enable, padding, -KVM_EINVAL); + cmd_vcpu_control_cr(vm, cr_inval, enable, no_padding, -KVM_EINVAL); +} + +static void test_cmd_vcpu_control_cr(struct kvm_vm *vm) +{ + struct vcpu_worker_data data = { + .vm = vm, + .vcpu_id = VCPU_ID, + .test_id = GUEST_TEST_CR, + }; + struct kvmi_msg_hdr hdr; + struct { + struct kvmi_event common; + struct kvmi_event_cr cr; + } ev; + struct { + struct vcpu_reply common; + struct kvmi_event_cr_reply cr; + } rpl = {}; + __u16 event_id = KVMI_EVENT_CR; + __u8 cr_no = 4; + struct kvm_sregs sregs; + pthread_t vcpu_thread; + + enable_cr_events(vm, cr_no); + + vcpu_thread = start_vcpu_worker(&data); + + receive_event(&hdr, &ev.common, sizeof(ev), event_id); + + pr_info("CR%u, old 0x%llx, new 0x%llx\n", + ev.cr.cr, ev.cr.old_value, ev.cr.new_value); + + TEST_ASSERT(ev.cr.cr == cr_no, + "Unexpected CR event, received CR%u, expected CR%u", + ev.cr.cr, cr_no); + + rpl.cr.new_val = ev.cr.old_value; + + reply_to_event(&hdr, &ev.common, KVMI_EVENT_ACTION_CONTINUE, + &rpl.common, sizeof(rpl)); + + stop_vcpu_worker(vcpu_thread, &data); + + disable_cr_events(vm, cr_no); + + vcpu_sregs_get(vm, VCPU_ID, &sregs); + TEST_ASSERT(sregs.cr4 == ev.cr.old_value, + "Failed to block CR4 update, CR4 0x%llx, expected 0x%llx", + sregs.cr4, ev.cr.old_value); + + test_invalid_vcpu_control_cr(vm); +} + static void test_introspection(struct kvm_vm *vm) { srandom(time(0)); @@ -1224,6 +1331,7 @@ static void test_introspection(struct kvm_vm *vm) test_event_hypercall(vm); test_event_breakpoint(vm); test_cmd_vm_control_cleanup(vm); + test_cmd_vcpu_control_cr(vm); unhook_introspection(vm); } diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c index db1f4523cec5..2dd82aa5e11c 100644 --- a/virt/kvm/introspection/kvmi.c +++ b/virt/kvm/introspection/kvmi.c @@ -98,6 +98,7 @@ static void setup_known_events(void) bitmap_zero(Kvmi_known_vcpu_events, KVMI_NUM_EVENTS); set_bit(KVMI_EVENT_BREAKPOINT, Kvmi_known_vcpu_events); + set_bit(KVMI_EVENT_CR, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_HYPERCALL, Kvmi_known_vcpu_events); set_bit(KVMI_EVENT_PAUSE_VCPU, Kvmi_known_vcpu_events); diff --git a/virt/kvm/introspection/kvmi_int.h b/virt/kvm/introspection/kvmi_int.h index 831e7e14524f..c206376eb0ad 100644 --- a/virt/kvm/introspection/kvmi_int.h +++ b/virt/kvm/introspection/kvmi_int.h @@ -31,6 +31,9 @@ bool kvmi_sock_get(struct kvm_introspection *kvmi, int fd); void kvmi_sock_shutdown(struct kvm_introspection *kvmi); void kvmi_sock_put(struct kvm_introspection *kvmi); bool kvmi_msg_process(struct kvm_introspection *kvmi); +int kvmi_send_event(struct kvm_vcpu *vcpu, u32 ev_id, + void *ev, size_t ev_size, + void *rpl, size_t rpl_size, int *action); 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); @@ -50,6 +53,8 @@ void kvmi_run_jobs(struct kvm_vcpu *vcpu); void kvmi_post_reply(struct kvm_vcpu *vcpu); void kvmi_handle_common_event_actions(struct kvm *kvm, u32 action); void kvmi_cmd_vm_control_cleanup(struct kvm_introspection *kvmi, bool enable); +struct kvm_introspection * __must_check kvmi_get(struct kvm *kvm); +void kvmi_put(struct kvm *kvm); int kvmi_cmd_vm_control_events(struct kvm_introspection *kvmi, unsigned int event_id, bool enable); int kvmi_cmd_vcpu_control_events(struct kvm_vcpu *vcpu, @@ -90,5 +95,7 @@ void kvmi_arch_hypercall_event(struct kvm_vcpu *vcpu); void kvmi_arch_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len); int kvmi_arch_cmd_control_intercept(struct kvm_vcpu *vcpu, unsigned int event_id, bool enable); +int kvmi_arch_cmd_vcpu_control_cr(struct kvm_vcpu *vcpu, + const struct kvmi_vcpu_control_cr *req); #endif diff --git a/virt/kvm/introspection/kvmi_msg.c b/virt/kvm/introspection/kvmi_msg.c index 86cee47d214f..330fad27e1df 100644 --- a/virt/kvm/introspection/kvmi_msg.c +++ b/virt/kvm/introspection/kvmi_msg.c @@ -481,6 +481,17 @@ static int handle_vcpu_get_cpuid(const struct kvmi_vcpu_msg_job *job, return kvmi_msg_vcpu_reply(job, msg, ec, &rpl, sizeof(rpl)); } +static int handle_vcpu_control_cr(const struct kvmi_vcpu_msg_job *job, + const struct kvmi_msg_hdr *msg, + const void *req) +{ + int ec; + + ec = kvmi_arch_cmd_vcpu_control_cr(job->vcpu, req); + + return kvmi_msg_vcpu_reply(job, msg, ec, NULL, 0); +} + /* * These functions are executed from the vCPU thread. The receiving thread * passes the messages using a newly allocated 'struct kvmi_vcpu_msg_job' @@ -490,6 +501,7 @@ static int handle_vcpu_get_cpuid(const struct kvmi_vcpu_msg_job *job, static int(*const msg_vcpu[])(const struct kvmi_vcpu_msg_job *, const struct kvmi_msg_hdr *, const void *) = { [KVMI_EVENT] = handle_vcpu_event_reply, + [KVMI_VCPU_CONTROL_CR] = handle_vcpu_control_cr, [KVMI_VCPU_CONTROL_EVENTS] = handle_vcpu_control_events, [KVMI_VCPU_GET_CPUID] = handle_vcpu_get_cpuid, [KVMI_VCPU_GET_INFO] = handle_vcpu_get_info, @@ -758,9 +770,9 @@ static void kvmi_setup_vcpu_reply(struct kvm_vcpu_introspection *vcpui, vcpui->waiting_for_reply = true; } -static int kvmi_send_event(struct kvm_vcpu *vcpu, u32 ev_id, - void *ev, size_t ev_size, - void *rpl, size_t rpl_size, int *action) +int kvmi_send_event(struct kvm_vcpu *vcpu, u32 ev_id, + void *ev, size_t ev_size, + void *rpl, size_t rpl_size, int *action) { struct kvmi_msg_hdr hdr; struct kvmi_event common;