05.2 virtio introduction
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05.2 virtio introduction Presentation Transcript

  • 1. VIRTIO Yi-Man Ma & Chang-Jung Lin 2011 / 01 / 05Thursday, January 5, 12 1
  • 2. Agenda Introduction Architecture VirtQueue & Vring Five APIs Adding a new Virtio Device / DriverThursday, January 5, 12 2
  • 3. INTRODUCTIONThursday, January 5, 12 3
  • 4. ct ion du In tro Create a shortcut to deal with IO Request Coalesced IO Request by VirtQueueThursday, January 5, 12 4
  • 5. ct ion du In tro Device emulation in full virtualization and paravirtualization environments Guest operating system Guest operating system Para-drivers Traps Interfaces Hypervisor Hypervisor (Full virtualization) Device emulation (Full virtualization) Device emulation Hardware HardwareThursday, January 5, 12 5
  • 6. ARCHITECTUREThursday, January 5, 12 6
  • 7. tu re hit ec A rc GUEST1 GUEST2 Transport Transport Other QEMU QEMU Processes KVM Host HardwareThursday, January 5, 12 7
  • 8. tu re hit ec A rc Virtio Driver Guest Virtio PCI Controller Vring Transport Virtio PCI Controller QEMU Virtio DeviceThursday, January 5, 12 8
  • 9. VIRTQUEUE & VRINGThursday, January 5, 12 9
  • 10. ue ue Vi rtQ Each Device have it’s own virtqueues. Queue RequestsThursday, January 5, 12 10
  • 11. V ri ng Each virtqueue have it’s own vring. Memory Mapped between QEMU & Guest Actual memory layout for queueThursday, January 5, 12 11
  • 12. ue ng ue ri Vi rtQ V Find virtqueue Virtio Driver Guest Virtio PCI Controller Alloc Vring Vring Transport Virtio PCI Controller Vring GPA QEMU Virtio DeviceThursday, January 5, 12 12
  • 13. ue ng ue ri Vi rtQ V Virtio Driver Virt queue Write Virt queue Read Vring Vring Virtio DeviceThursday, January 5, 12 13
  • 14. ue ng ue ri Vi rtQ V Virtio Driver Virt queue Write Virt queue Read Vring Vring Virtio DeviceThursday, January 5, 12 14
  • 15. ue ng ue ri Vi rtQ V Virtio Driver Add Buf Virt queue Write Virt queue Read Vring In Out Vring data Virtio DeviceThursday, January 5, 12 15
  • 16. ue ng ue ri Vi rtQ V Kick Virtio Driver Virt queue Write Virt queue Read Vring In Out Vring data Virtio DeviceThursday, January 5, 12 16
  • 17. ue ng ue ri Vi rtQ V Virtio Driver Virt queue Write Virt queue Read Vring In Out Vring data POP Virtio DeviceThursday, January 5, 12 17
  • 18. ue ng ue ri Vi rtQ V Virtio Driver Virt queue Write Virt queue Read Vring In Out Vring data Push Virtio DeviceThursday, January 5, 12 18
  • 19. ue ng ue ri Vi rtQ V Virtio Driver Get Buf Virt queue Write Virt queue Read data Vring In Out Vring Virtio DeviceThursday, January 5, 12 19
  • 20. FIVE APISThursday, January 5, 12 20
  • 21. APIs F ive add_buf kick get_buf disable_cb enable_cbThursday, January 5, 12 21
  • 22. Is et buf AP g F ive add & add_buf expose buffer to other end get_buf get the next used bufferThursday, January 5, 12 22
  • 23. Is AP ick F ive k kick update after add_buf notify QEMU to deal with the dataThursday, January 5, 12 23
  • 24. Is ative AP el F ive C Br disable_cb disable callbacks not necessarily synchronous unreliable and only useful as an optimization enable_cb restart callbacks after disable_cbThursday, January 5, 12 24
  • 25. NEW DEVICE / DRIVERThursday, January 5, 12 25
  • 26. river D New include/linux/virtio_ids.h include/linux/virtio.h include/linux/virtio_[device].h drivers/virtio/virtio_[device].c drivers/virtio/virtio_pci.cThursday, January 5, 12 26
  • 27. ev ice D New hw/virtio-[device].c hw/virtio-[device].h hw/pci.h hw/virtio_pci.cThursday, January 5, 12 27
  • 28. tu re hit ec A rc Virtio Driver Guest Virtio PCI Controller Vring Transport Virtio PCI Controller QEMU Virtio DeviceThursday, January 5, 12 28
  • 29. ev iceeid D devic Virtio PCI Controller New add Modify qemu-src/hw/pci.h #define PCI_DEVICE_ID_VIRTIO_[device] 0x1004Thursday, January 5, 12 29
  • 30. icde r ev le Dal han Virtio PCI Controller Newiniti Modify qemu-src/hw/virtio-pci.c static int virtio_[device]_init_pci(PCIDevice *pci_dev) { VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev); VirtIODevice *vdev; vdev = virtio_[device]_init(&pci_dev->qdev); if (!vdev) { return -1; } virtio_init_pci(proxy, vdev); return 0; }Thursday, January 5, 12 30
  • 31. ev ce idler Dt han Virtio PCI Controller New exi Modify qemu-src/hw/virtio-pci.c static int virtio_[device]_exit_pci (PCIDevice *pci_dev) { VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev); virtio_pci_stop_ioeventfd(proxy); virtio_[device]_exit(proxy->vdev); return virtio_exit_pci(pci_dev); }Thursday, January 5, 12 31
  • 32. ieciefo ev n D evic wdd d Virtio PCI Controller Nea Modify qemu-src/hw/virtio-pci.c static PCIDeviceInfo virtio_info[] = { { .qdev.name = "virtio-[device]-pci", .qdev.alias = "virtio-[device]", .init = virtio_[device]_init_pci, exit . = virtio_[device]_exit_pci, device_id = PCI_DEVICE_ID_VIRTIO_[device], . .qdev.props = (Property[]) { DEFINE_VIRTIO_COMMON_FEATURES( VirtIOPCIProxy, host_features), DEFINE_PROP_END_OF_LIST(), , } ...... (Skip)Thursday, January 5, 12 32
  • 33. tu re hit ec A rc Virtio Driver Guest Virtio PCI Controller Vring Transport Virtio PCI Controller QEMU Virtio DeviceThursday, January 5, 12 33
  • 34. ev ice D Virtio Device New Add virtio-[device].c, virtio[device].h Put them under the directory qemu-src/hw/Thursday, January 5, 12 34
  • 35. ivcce].h ev i e D-[de Virtio Device ewirtio N v #ifndef _QEMU_VIRTIO_[device]_H #include "virtio.h“ #define _QEMU_VIRTIO_[device]_H #define VIRTIO_ID_[device] [num] //ID for your device VirtIODevice *virtio_[device]_init(DeviceState *dev); void virtio_[device]_exit(VirtIODevice *vdev); #endifThursday, January 5, 12 35
  • 36. ivcce].c ev i e D-[de Virtio Device ewirtio N v #include <qemu-common.h> #include "qemu-error.h" #include "virtio-[device].h" #include "virtio.h" typedef struct VirtIO[device] { VirtIODevice vdev; VirtQueue *vq[num]; DeviceState *qdev; int status; } VirtIO[device]; struct virtio_[device]_config { int config; };Thursday, January 5, 12 36
  • 37. ictere evuc u D str Virtio Device ewirtio N v struct VirtIODevice { ........... uint32_t (*get_features)(VirtIODevice *vdev, uint32_t requested_features); uint32_t (*bad_features)(VirtIODevice *vdev); void (*set_features)(VirtIODevice *vdev, uint32_t val); void (*get_config)(VirtIODevice *vdev, uint8_t *config); void (*set_config)(VirtIODevice *vdev, const uint8_t *config); void (*reset)(VirtIODevice *vdev); void (*set_status)(VirtIODevice *vdev, uint8_t val); ....... };Thursday, January 5, 12 37
  • 38. iece nt evl me Dimp Virtio Device eweed N n static VirtIO[device] *to_virtio_[device](VirtIODevice *vdev) //Get device defined by yourself static uint32_t virtio_[device]_ get_features (VirtIODevice *vdev, uint32_t features); static uint32_t virtio_[device]_ bad_features (VirtIODevice *vdev); static void virtio_[device]_ set_features (VirtIODevice *vdev, uint32_t val); static void virtio_[device]_ get_config (VirtIODevice *vdev, uint8_t *config); static void virtio_[device]_ set_config (VirtIODevice *vdev, const uint8_t *config);Thursday, January 5, 12 38
  • 39. iece nt evl me Dimp Virtio Device eweed N n static void virtio_[device]_ reset (VirtIODevice *vdev); static void virtio_[device]_ set_status (VirtIODevice *vdev, uint8_t val); VirtIODevice *virtio_[device]_init(DeviceState *dev); //Initialize your device void virtio_[device]_exit (VirtIODevice *vdev); static void virtio_[device]_save(QEMUFile *f, void *opaque); static int virtio_[device]_load(QEMUFile *f, void *opaque, int version_id); static void virtio_[device]_handle_out(VirtIODevice *vdev, VirtQueue *vq);Thursday, January 5, 12 39
  • 40. itcees ev ur Dt fea Virtio Device ew bou N a static uint32_t virtio_[device]_ get_features (VirtIODevice *vdev, uint32_t features) { VirtIO[device] *n = to_virtio_[device](vdev); return features; } static uint32_t virtio_[device]_ bad_features (VirtIODevice *vdev){ uint32_t features = 0; return features; } static void virtio_[device]_ set_features (VirtIODevice *vdev, uint32_t val){ VirtIOMy *n = to_virtio_[device](vdev); }Thursday, January 5, 12 40
  • 41. e icfig Dut c evon Virtio Device Newabo static void virtio_[device]_ get_config (VirtIODevice *vdev, uint8_t *config) { VirtIO[device] *n = to_virtio_[device](vdev); struct virtio_[device]_config cfg; stw_p(&cfg.config, n->status); memcpy(config, &cfg, sizeof(cfg)); } static void virtio_[device]_ set_config (VirtIODevice *vdev, const uint8_t *config) { VirtIO[de vice] *n = to_virtio_[device](vdev); struct virtio_[device]_config cfg; }Thursday, January 5, 12 41
  • 42. icee eves t D& r w set Virtio Device Ne static void virtio_[device]_ reset (VirtIODevice *vdev) { } static void virtio_[device]_ set_status (VirtIODevice *vdev, uint8_t val) { VirtIO[device] *n = to_virtio_my(vdev); }Thursday, January 5, 12 42
  • 43. e icice Dial de ev v Virtio Device New init VirtIODevice *virtio_[device]_init(DeviceState *dev) { VirtIO[device] *s; s = (VirtIO[device]*)virtio_common_init("virtio-[device]", VIRTIO_ID_[device], sizeof(struct virtio_[device]_config), sizeof(VirtIO[device])); s->vdev.get_config = virtio_[device]get_config; s->vdev.set_config = virtio_[device]_set_config; s->vdev.get_features = virtio_[device]_get_features; s->vdev.set_features = virtio_[device]_set_features; s->vdev.bad_features = virtio_[device]_bad_features; s->vdev.reset = virtio_[device]_reset; s->vdev.set_status = virtio_[device]_set_status; .....Thursday, January 5, 12 43
  • 44. e icice Dial de ev v Virtio Device New init ..... s->vdev.set_status = virtio_[device]_set_status; s->vq[0] = virtio_add_queue(&s->vdev, 1024, virtio_[device]_handle_out1); s->vq[1] = virtio_add_queue(&s->vdev, 1024, virtio_[device]_handle_out2); s->qdev = dev; s->status = 99; register_savevm(dev, "virtio-[device]”, 0, 2, virtio_[device]_save, virtio_[device]_load, s); return &s->vdev; }Thursday, January 5, 12 44
  • 45. ivcce ev i e Dit de Virtio Device New ex void virtio_[device]_exit (VirtIODevice *vdev) { VirtIO[device] *s = to_virtio_[device](vdev); unregister_savevm(s->qdev, "virtio-[device]“ , s); }Thursday, January 5, 12 45
  • 46. e iloae v cd De & Virtio Device New sav static void virtio_[device]_save(QEMUFile *f, void *opaque) { VirtIO[device] *n = opaque; virtio_save(&n->vdev, f); } static int virtio_[device]_load(QEMUFile *f, void *opaque, int version_id) { VirtIO[device] *n = opaque; virtio_load(&n->vdev, f); return 0; }Thursday, January 5, 12 46
  • 47. icler ev d e Da han Virtio Device Newdat static void virtio_[device]_handle_out(VirtIODevice *vdev, VirtQueue *vq) { VirtIO[device] *n = to_virtio_my(vdev); VirtQueueElement elem1, elem2; int K; memset(&elem1, 0, sizeof(elem1)); memset(&elem2, 0, sizeof(elem2)); virtqueue_pop(vq, &elem1); if(memcmp(&elem1, &elem2, sizeof(elem1))) printf("something happened!!!n"); K = *((int*)elem1.out_sg[0].iov_base) + 1; memcpy(elem1.in_sg[0].iov_base, &K, sizeof(int)); virtqueue_push(vq, &elem1, sizeof(int)); }Thursday, January 5, 12 47
  • 48. tu re hit ec A rc Virtio Driver Guest Virtio PCI Controller Vring Transport Virtio PCI Controller QEMU Virtio DeviceThursday, January 5, 12 48
  • 49. r eid Devic rive Virtio Driver New d Modify kernel-src/include/linux/virtio-ids.h #define VIRTIO_ID_[device] number Should be the same number as defined in qemuThursday, January 5, 12 49
  • 50. river D Virtio Driver New #include "linux/virtio.h“ #include "linux/virtio_ids.h“ #include "linux/virtio_pci.h“ #include "virtio.h" static struct virtio_device_id id_table[] = { {VIRTIO_ID_[device], VIRTIO_DEV_ANY_ID}, {0} }; struct virtio_[device]{ int size; void* data; void* mapbuf; struct semaphore sem; struct cdev cdev; struct virtio_device *vdev; struct virtqueue *vq[2]; } my_cdev;Thursday, January 5, 12 50
  • 51. ecrure riv u t De str Virtio Driver ewefin N d static struct virtio_driver virtio_[device]_driver = { .feature_table = features, .feature_table_size = ARRAY_SIZE(features), .driver.name = KBUILD_MODNAME, .driver.owner = THIS_MODULE, .id_table = id_table, .probe = my_probe, .remove = __devexit_p(my_remove), };Thursday, January 5, 12 51
  • 52. river D Virtio Driver New Register & unregister driver - two APIs register_virtio_driver(&virtio_[device]_driver); unregister_virtio_driver(&virtio_[device]_driver);Thursday, January 5, 12 52
  • 53. tu re hit ec A rc Virtio Driver Guest Virtio PCI Controller Vring Transport Virtio PCI Controller QEMU Virtio DeviceThursday, January 5, 12 53
  • 54. ati on nviec side uri r Vring omm d C Declare necessary parameter char * buffer1, buffer2; int* A[2] = {buffer1, buffer2}; struct scatterlist sg[2]; /*0 for output, 1 for input*/ struct virtqueue *vq[2]; const char *names[2] = { “[Q1]“ , “[Q2]“ }; vq_callback_t *cb[2] = {NULL, NULL}; Find virtqueue vdev->config->find_vqs(vdev, 2, vq, cb, names); my_cdev.vq[0] = vq[0]; my_cdev.vq[1] = vq[1];Thursday, January 5, 12 54
  • 55. ati on nviec side uri r Vring omm d C Send data to qemu sg_init_table(sg, ARRAY_SIZE(sg)); sg_set_buf(&sg[0], buffer1, [count]); sg_set_buf(&sg[1], buffer2, [count]); virtqueue_add_buf(myc->vq[0], sg, /*out*/1, /*in*/1, A); virtqueue_kick(myc->vq[0]); Get data from qemu virtqueue_get_buf(myc->vq[0], &len);Thursday, January 5, 12 55
  • 56. ati on niicc side uev e Vring omm d C Set virtqueue handler @init function s->vq[0] = virtio_add_queue(&s->vdev, 1024, virtio_[device]_handle_out1); s->vq[1] = virtio_add_queue(&s->vdev, 1024, virtio_[device]_handle_out2); Declare variable for data @virtqueue handler VirtQueueElement elem1, elem2; memset(&elem1, 0, sizeof(elem1)); memset(&elem2, 0, sizeof(elem2));Thursday, January 5, 12 56
  • 57. ati on niicc side uev e Vring omm d C VirtQueueElement typedef struct VirtQueueElement { unsigned int index; unsigned int out_num; unsigned int in_num; target_phys_addr_t in_addr[VIRTQUEUE_MAX_SIZE]; target_phys_addr_t out_addr[VIRTQUEUE_MAX_SIZE]; struct iovec in_sg[VIRTQUEUE_MAX_SIZE]; struct iovec out_sg[VIRTQUEUE_MAX_SIZE]; } VirtQueueElement;Thursday, January 5, 12 57
  • 58. ati on niicc side uev e Vring omm d C Pop virtqueue_pop(vq, &elem1); Check if data exist if(memcmp(&elem1, &elem2, sizeof(elem1))) do something; Put data to elem memcpy(elem1.in_sg[0].iov_base, &data, sizeof(data)); Push data back to guest elem1.in_sg[0].iov_len = sizeof(data); virtqueue_push(vq, &elem1, sizeof(data));Thursday, January 5, 12 58
  • 59. en ce R e fer Virtio: An I/O virtualization framework for Linux http://www.ibm.com/developerworks/linux/library/l-virtio/ index.html?ca=dgr-lnxw97Viriodth- LX&S_TACT=105AGX59&S_CMP=grlnxw97 virtio: Towards a De-Facto Standard For Virtual IO Devices http://www.tdeig.ch/kvm/pasche/32_virtio_Russel.pdf QEMU & Kernel Source Code http://kernel.org/ http://wiki.qemu.org/Thursday, January 5, 12 59