In certain situations (when the guest has to be paused, suspended, migrated, etc.), userspace/QEMU will use the KVM_INTROSPECTION_UNHOOK ioctl in order to trigger the KVMI_EVENT_UNHOOK. If the event is sent successfully (the VM has an active introspection channel), userspace should delay the action (pause/suspend/...) to give the introspection tool the chance to remove its hooks (eg. breakpoints). Once a timeout is reached or the introspection tool has closed the socket, QEMU should continue with the planned action.
Signed-off-by: Adalbert Lazăr <[email protected]> --- Documentation/virtual/kvm/kvmi.rst | 20 ++++++++++++++++++ virt/kvm/kvmi.c | 34 +++++++++++++++++++++++++++++- virt/kvm/kvmi_int.h | 1 + virt/kvm/kvmi_msg.c | 20 ++++++++++++++++++ 4 files changed, 74 insertions(+), 1 deletion(-) diff --git a/Documentation/virtual/kvm/kvmi.rst b/Documentation/virtual/kvm/kvmi.rst index 1ea4be0d5a45..28e1a1c80551 100644 --- a/Documentation/virtual/kvm/kvmi.rst +++ b/Documentation/virtual/kvm/kvmi.rst @@ -493,3 +493,23 @@ Some of the events accept the KVMI_EVENT_ACTION_RETRY action, to continue by re-entering the guest. Specific data can follow these common structures. + +1. KVMI_EVENT_UNHOOK +-------------------- + +:Architecture: all +:Versions: >= 1 +:Actions: CONTINUE, CRASH +:Parameters: + +:: + + struct kvmi_event; + +:Returns: none + +This event is sent when the device manager (ie. QEMU) has to +pause/stop/migrate the guest (see **Unhooking**) and the introspection +has been enabled for this event (see **KVMI_CONTROL_VM_EVENTS**). +The introspection tool has a chance to unhook and close the KVMI channel +(signaling that the operation can proceed). diff --git a/virt/kvm/kvmi.c b/virt/kvm/kvmi.c index 0d3560b74f2d..7eda49bf65c4 100644 --- a/virt/kvm/kvmi.c +++ b/virt/kvm/kvmi.c @@ -644,6 +644,9 @@ int kvmi_cmd_control_vm_events(struct kvmi *ikvm, unsigned int event_id, static void kvmi_job_abort(struct kvm_vcpu *vcpu, void *ctx) { + struct kvmi_vcpu *ivcpu = IVCPU(vcpu); + + ivcpu->reply_waiting = false; } static void kvmi_abort_events(struct kvm *kvm) @@ -655,6 +658,34 @@ static void kvmi_abort_events(struct kvm *kvm) kvmi_add_job(vcpu, kvmi_job_abort, NULL, NULL); } +static bool __kvmi_unhook_event(struct kvmi *ikvm) +{ + int err; + + if (!test_bit(KVMI_EVENT_UNHOOK, ikvm->vm_ev_mask)) + return false; + + err = kvmi_msg_send_unhook(ikvm); + + return !err; +} + +static bool kvmi_unhook_event(struct kvm *kvm) +{ + struct kvmi *ikvm; + bool ret = true; + + ikvm = kvmi_get(kvm); + if (!ikvm) + return false; + + ret = __kvmi_unhook_event(ikvm); + + kvmi_put(kvm); + + return ret; +} + int kvmi_ioctl_unhook(struct kvm *kvm, bool force_reset) { struct kvmi *ikvm; @@ -664,7 +695,8 @@ int kvmi_ioctl_unhook(struct kvm *kvm, bool force_reset) if (!ikvm) return -EFAULT; - kvm_info("TODO: %s force_reset %d", __func__, force_reset); + if (!force_reset && !kvmi_unhook_event(kvm)) + err = -ENOENT; kvmi_put(kvm); diff --git a/virt/kvm/kvmi_int.h b/virt/kvm/kvmi_int.h index 70c8ca0343a3..9750a9b9902b 100644 --- a/virt/kvm/kvmi_int.h +++ b/virt/kvm/kvmi_int.h @@ -123,6 +123,7 @@ bool kvmi_sock_get(struct kvmi *ikvm, int fd); void kvmi_sock_shutdown(struct kvmi *ikvm); void kvmi_sock_put(struct kvmi *ikvm); bool kvmi_msg_process(struct kvmi *ikvm); +int kvmi_msg_send_unhook(struct kvmi *ikvm); /* kvmi.c */ void *kvmi_msg_alloc(void); diff --git a/virt/kvm/kvmi_msg.c b/virt/kvm/kvmi_msg.c index 536034e1bea7..0c7c1e968007 100644 --- a/virt/kvm/kvmi_msg.c +++ b/virt/kvm/kvmi_msg.c @@ -705,3 +705,23 @@ int kvmi_send_event(struct kvm_vcpu *vcpu, u32 ev_id, return err; } +int kvmi_msg_send_unhook(struct kvmi *ikvm) +{ + struct kvmi_msg_hdr hdr; + struct kvmi_event common; + struct kvec vec[] = { + {.iov_base = &hdr, .iov_len = sizeof(hdr) }, + {.iov_base = &common, .iov_len = sizeof(common)}, + }; + size_t msg_size = sizeof(hdr) + sizeof(common); + size_t n = ARRAY_SIZE(vec); + + memset(&hdr, 0, sizeof(hdr)); + hdr.id = KVMI_EVENT; + hdr.seq = new_seq(ikvm); + hdr.size = msg_size - sizeof(hdr); + + kvmi_setup_event_common(&common, KVMI_EVENT_UNHOOK, 0); + + return kvmi_sock_write(ikvm, vec, n, msg_size); +} _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
