The main goal is to add an example device to Qemu to be used as template or guideline for contributors when they wish to create a new virtio device.
Another reason for this device is to document "the right way" to write a new virtio device in Qemu. This device is a simple device and its functionality is to increase its input by 1. The device driver is located at: https://github.com/ybettan/QemuDeviceDrivers.git In addition I am writing a blog to give a logical overview of the virtio protocol and a step-by-step guide to write a new virtio device. This blog can be found at https://howtovms.wordpress.com. scripts/checkpatch.pl have some errors do to "//" (old style one line comment), those lines contains FIXMEs for the next version and will be removed. Signed-off-by: Yoni Bettan <ybet...@redhat.com> --- hw/virtio/Makefile.objs | 1 + hw/virtio/virtio-example.c | 121 ++++++++++++++++++ hw/virtio/virtio-pci.c | 49 +++++++ hw/virtio/virtio-pci.h | 14 ++ include/hw/pci/pci.h | 1 + include/hw/virtio/virtio-example.h | 31 +++++ .../standard-headers/linux/virtio_example.h | 8 ++ include/standard-headers/linux/virtio_ids.h | 1 + 8 files changed, 226 insertions(+) create mode 100644 hw/virtio/virtio-example.c create mode 100644 include/hw/virtio/virtio-example.h create mode 100644 include/standard-headers/linux/virtio_example.h diff --git a/hw/virtio/Makefile.objs b/hw/virtio/Makefile.objs index 1b2799cfd8..7a6fb2505c 100644 --- a/hw/virtio/Makefile.objs +++ b/hw/virtio/Makefile.objs @@ -7,6 +7,7 @@ common-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o common-obj-$(CONFIG_VIRTIO_MMIO) += virtio-mmio.o obj-$(CONFIG_VIRTIO_BALLOON) += virtio-balloon.o obj-$(CONFIG_VIRTIO_CRYPTO) += virtio-crypto.o +obj-$(CONFIG_VIRTIO_CRYPTO) += virtio-example.o obj-$(call land,$(CONFIG_VIRTIO_CRYPTO),$(CONFIG_VIRTIO_PCI)) += virtio-crypto-pci.o obj-$(CONFIG_LINUX) += vhost.o vhost-backend.o vhost-user.o diff --git a/hw/virtio/virtio-example.c b/hw/virtio/virtio-example.c new file mode 100644 index 0000000000..3c170f8022 --- /dev/null +++ b/hw/virtio/virtio-example.c @@ -0,0 +1,121 @@ +/* + * A virtio device example. + * + * Copyright 2019 Red Hat, Inc. + * Copyright 2019 Yoni Bettan <ybet...@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * (at your option) any later version. See the COPYING file in the + * top-level directory. + */ + +#include "qemu/osdep.h" +#include "qemu/iov.h" +#include "hw/virtio/virtio.h" +#include "hw/virtio/virtio-example.h" + +#define MAX_DATA_SIZE 10 + + +/* + * this function is called when the driver 'kick' the virtqueue. + * since we can have more than 1 virtqueue we need the vq argument in order to + * know which one was kicked by the driver. + */ +static void handle_input(VirtIODevice *vdev, VirtQueue *vq) +{ + VirtQueueElement *elem; + int data, len; + char buf[MAX_DATA_SIZE]; + + /* check that virtqueue have at least 2 elements, input and output */ + //FIXME: implement + + /* get the virtqueue input element sent from the driver */ + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); + + /* read the input element (sg) into a buffer */ + len = iov_to_buf(elem->in_sg, elem->out_num, 0, buf, MAX_DATA_SIZE); + //FIXME: should i check buffer overflow, or iov_to_buf() is safe ? + if (len > MAX_DATA_SIZE) { + goto error; + } + + /* process the data */ + data = atoi(buf); + sprintf(buf, "%d", ++data); + + /* get the virtqueue output element sent from the driver */ + elem = virtqueue_pop(vq, sizeof(VirtQueueElement)); + + /* write the result to the output element (sg) */ + len = iov_from_buf(elem->in_sg, elem->in_num, 0, buf, MAX_DATA_SIZE); + //FIXME: should i check buffer overflow, or iov_from_buf() is safe ? + + /* push back the result into the virtqueue */ + virtqueue_push(vq, elem, /*len=*/1); + + /* interrupt the driver */ + virtio_notify(vdev, vq); + + return; + +error: + printf("ERROR: buffer overflow\n"); + //FIXME: can we make the request fail ?, if iov_*_buf is safe we don't need it +} + +/* + * There is no currently defined feature bits, we still need this function + * because the backend driver checks that VirtioDeviceClass.get_features is + * initialized + */ +static uint64_t get_features(VirtIODevice *vdev, uint64_t features, Error **errp) +{ + return features; +} + +static void virtio_example_device_realize(DeviceState *dev, Error **errp) +{ + VirtIODevice *vdev = VIRTIO_DEVICE(dev); + VirtIOEXAMPLE *vexmp = VIRTIO_EXAMPLE(dev); + + /* base class initialization */ + virtio_init(vdev, "virtio-example", VIRTIO_ID_EXAMPLE, /*config_size=*/0); + + /* this device suppot 1 virtqueue */ + vexmp->vq = virtio_add_queue(vdev, 8, handle_input); +} + +static void virtio_example_device_unrealize(DeviceState *dev, Error **errp) +{ + VirtIODevice *vdev = VIRTIO_DEVICE(dev); + + /* base class cleanup */ + virtio_cleanup(vdev); +} + +static void virtio_example_class_init(ObjectClass *klass, void *data) +{ + DeviceClass *dc = DEVICE_CLASS(klass); + VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass); + + set_bit(DEVICE_CATEGORY_MISC, dc->categories); + vdc->realize = virtio_example_device_realize; + vdc->unrealize = virtio_example_device_unrealize; + vdc->get_features = get_features; +} + +static const TypeInfo virtio_example_info = { + .name = TYPE_VIRTIO_EXAMPLE, + .parent = TYPE_VIRTIO_DEVICE, + .instance_size = sizeof(VirtIOEXAMPLE), + .class_init = virtio_example_class_init, +}; + +static void virtio_register_types(void) +{ + type_register_static(&virtio_example_info); +} + +type_init(virtio_register_types) diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 3a01fe90f0..99fc6ce79b 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -2521,6 +2521,54 @@ static const TypeInfo virtio_rng_pci_info = { .class_init = virtio_rng_pci_class_init, }; +/* virtio-example-pci */ + +static void virtio_example_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) +{ + VirtIOExamplePCI *vexmp = VIRTIO_EXAMPLE_PCI(vpci_dev); + DeviceState *vdev = DEVICE(&vexmp->vdev); + Error *err = NULL; + + qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus)); + object_property_set_bool(OBJECT(vdev), true, "realized", &err); + if (err) { + error_propagate(errp, err); + return; + } + +} + +static void virtio_example_pci_class_init(ObjectClass *klass, void *data) +{ + DeviceClass *dc = DEVICE_CLASS(klass); + VirtioPCIClass *k = VIRTIO_PCI_CLASS(klass); + PCIDeviceClass *pcidev_k = PCI_DEVICE_CLASS(klass); + + k->realize = virtio_example_pci_realize; + set_bit(DEVICE_CATEGORY_MISC, dc->categories); + + pcidev_k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET; + pcidev_k->device_id = PCI_DEVICE_ID_VIRTIO_EXAMPLE; + pcidev_k->revision = VIRTIO_PCI_ABI_VERSION; + pcidev_k->class_id = PCI_CLASS_OTHERS; +} + +static void virtio_example_initfn(Object *obj) +{ + VirtIOExamplePCI *dev = VIRTIO_EXAMPLE_PCI(obj); + + virtio_instance_init_common(obj, &dev->vdev, sizeof(dev->vdev), + TYPE_VIRTIO_EXAMPLE); +} + +static const TypeInfo virtio_example_pci_info = { + .name = TYPE_VIRTIO_EXAMPLE_PCI, + .parent = TYPE_VIRTIO_PCI, + .instance_size = sizeof(VirtIOExamplePCI), + .instance_init = virtio_example_initfn, + .class_init = virtio_example_pci_class_init, +}; + /* virtio-input-pci */ static Property virtio_input_pci_properties[] = { @@ -2693,6 +2741,7 @@ static const TypeInfo virtio_pci_bus_info = { static void virtio_pci_register_types(void) { type_register_static(&virtio_rng_pci_info); + type_register_static(&virtio_example_pci_info); type_register_static(&virtio_input_pci_info); type_register_static(&virtio_input_hid_pci_info); type_register_static(&virtio_keyboard_pci_info); diff --git a/hw/virtio/virtio-pci.h b/hw/virtio/virtio-pci.h index 813082b0d7..db3f5ec17d 100644 --- a/hw/virtio/virtio-pci.h +++ b/hw/virtio/virtio-pci.h @@ -19,6 +19,7 @@ #include "hw/virtio/virtio-blk.h" #include "hw/virtio/virtio-net.h" #include "hw/virtio/virtio-rng.h" +#include "hw/virtio/virtio-example.h" #include "hw/virtio/virtio-serial.h" #include "hw/virtio/virtio-scsi.h" #include "hw/virtio/virtio-balloon.h" @@ -51,6 +52,7 @@ typedef struct VHostSCSIPCI VHostSCSIPCI; typedef struct VHostUserSCSIPCI VHostUserSCSIPCI; typedef struct VHostUserBlkPCI VHostUserBlkPCI; typedef struct VirtIORngPCI VirtIORngPCI; +typedef struct VirtIOExamplePCI VirtIOExamplePCI; typedef struct VirtIOInputPCI VirtIOInputPCI; typedef struct VirtIOInputHIDPCI VirtIOInputHIDPCI; typedef struct VirtIOInputHostPCI VirtIOInputHostPCI; @@ -339,6 +341,18 @@ struct VirtIORngPCI { VirtIORNG vdev; }; +/* + * virtio-example-pci: This extends VirtioPCIProxy. + */ +#define TYPE_VIRTIO_EXAMPLE_PCI "virtio-example-pci" +#define VIRTIO_EXAMPLE_PCI(obj) \ + OBJECT_CHECK(VirtIOExamplePCI, (obj), TYPE_VIRTIO_EXAMPLE_PCI) + +struct VirtIOExamplePCI { + VirtIOPCIProxy parent_obj; + VirtIOEXAMPLE vdev; +}; + /* * virtio-input-pci: This extends VirtioPCIProxy. */ diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h index 990d6fcbde..c69d5997b7 100644 --- a/include/hw/pci/pci.h +++ b/include/hw/pci/pci.h @@ -83,6 +83,7 @@ extern bool pci_available; #define PCI_DEVICE_ID_VIRTIO_CONSOLE 0x1003 #define PCI_DEVICE_ID_VIRTIO_SCSI 0x1004 #define PCI_DEVICE_ID_VIRTIO_RNG 0x1005 +#define PCI_DEVICE_ID_VIRTIO_EXAMPLE 0x1006 //FIXME: update to valid ID #define PCI_DEVICE_ID_VIRTIO_9P 0x1009 #define PCI_DEVICE_ID_VIRTIO_VSOCK 0x1012 diff --git a/include/hw/virtio/virtio-example.h b/include/hw/virtio/virtio-example.h new file mode 100644 index 0000000000..c08db28e8f --- /dev/null +++ b/include/hw/virtio/virtio-example.h @@ -0,0 +1,31 @@ +/* + * Virtio EXAMPLE Support + * + * Copyright Red Hat, Inc. 2019 + * Copyright Yoni Bettan <ybet...@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * (at your option) any later version. See the COPYING file in the + * top-level directory. + */ + +#ifndef QEMU_VIRTIO_EXAMPLE_H +#define QEMU_VIRTIO_EXAMPLE_H + +#include "standard-headers/linux/virtio_example.h" + +#define TYPE_VIRTIO_EXAMPLE "virtio-example-device" +#define VIRTIO_EXAMPLE(obj) \ + OBJECT_CHECK(VirtIOEXAMPLE, (obj), TYPE_VIRTIO_EXAMPLE) +#define VIRTIO_EXAMPLE_GET_PARENT_CLASS(obj) \ + OBJECT_GET_PARENT_CLASS(obj, TYPE_VIRTIO_EXAMPLE) + +typedef struct VirtIOEXAMPLE { + VirtIODevice parent_obj; + + /* Only one vq - guest puts buffer(s) on it when it needs computation */ + VirtQueue *vq; + +} VirtIOEXAMPLE; + +#endif diff --git a/include/standard-headers/linux/virtio_example.h b/include/standard-headers/linux/virtio_example.h new file mode 100644 index 0000000000..6321c60c5c --- /dev/null +++ b/include/standard-headers/linux/virtio_example.h @@ -0,0 +1,8 @@ +#ifndef _LINUX_VIRTIO_EXAMPLE_H +#define _LINUX_VIRTIO_EXAMPLE_H +/* This header is BSD licensed so anyone can use the definitions to implement + * compatible drivers/servers. */ +#include "standard-headers/linux/virtio_ids.h" +#include "standard-headers/linux/virtio_config.h" + +#endif /* _LINUX_VIRTIO_EXAMPLE_H */ diff --git a/include/standard-headers/linux/virtio_ids.h b/include/standard-headers/linux/virtio_ids.h index 6d5c3b2d4f..30c189303b 100644 --- a/include/standard-headers/linux/virtio_ids.h +++ b/include/standard-headers/linux/virtio_ids.h @@ -43,5 +43,6 @@ #define VIRTIO_ID_INPUT 18 /* virtio input */ #define VIRTIO_ID_VSOCK 19 /* virtio vsock transport */ #define VIRTIO_ID_CRYPTO 20 /* virtio crypto */ +#define VIRTIO_ID_EXAMPLE 21 /* virtio example */ #endif /* _LINUX_VIRTIO_IDS_H */ -- 2.17.2
