virtio-rng: hardware random number generator device

The Linux kernel already has a virtio-rng driver, this is the device
implementation.

When the guest asks for entropy from the virtio hwrng, it puts a buffer
in the vq.  We then put entropy into that buffer, and push it back to
the guest.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
---
aliguori: converted to new RngBackend interface
aliguori: remove entropy needed event
aliguori: fix migration

hw/Makefile.objs

@@ -1,6 +1,7 @@
 common-obj-y = usb/ ide/
 common-obj-y += loader.o
 common-obj-$(CONFIG_VIRTIO) += virtio-console.o
+common-obj-$(CONFIG_VIRTIO) += virtio-rng.o
 common-obj-$(CONFIG_VIRTIO_PCI) += virtio-pci.o
 common-obj-y += fw_cfg.o
 common-obj-$(CONFIG_PCI) += pci.o pci_bridge.o pci_bridge_dev.o

hw/pci.h

@@ -76,6 +76,7 @@
 #define PCI_DEVICE_ID_VIRTIO_BALLOON     0x1002
 #define PCI_DEVICE_ID_VIRTIO_CONSOLE     0x1003
 #define PCI_DEVICE_ID_VIRTIO_SCSI        0x1004
+#define PCI_DEVICE_ID_VIRTIO_RNG         0x1005
 
 #define FMT_PCIBUS                      PRIx64
 

hw/s390-virtio-bus.c

@@ -26,6 +26,7 @@
 #include "loader.h"
 #include "elf.h"
 #include "hw/virtio.h"
+#include "hw/virtio-rng.h"
 #include "hw/virtio-serial.h"
 #include "hw/virtio-net.h"
 #include "hw/sysbus.h"
@@ -206,6 +207,18 @@ static int s390_virtio_scsi_init(VirtIOS390Device *dev)
     return s390_virtio_device_init(dev, vdev);
 }
 
+static int s390_virtio_rng_init(VirtIOS390Device *dev)
+{
+    VirtIODevice *vdev;
+
+    vdev = virtio_rng_init((DeviceState *)dev, &dev->rng);
+    if (!vdev) {
+        return -1;
+    }
+
+    return s390_virtio_device_init(dev, vdev);
+}
+
 static uint64_t s390_virtio_device_vq_token(VirtIOS390Device *dev, int vq)
 {
     ram_addr_t token_off;
@@ -448,6 +461,29 @@ static TypeInfo s390_virtio_serial = {
     .class_init    = s390_virtio_serial_class_init,
 };
 
+static void s390_virtio_rng_initfn(Object *obj)
+{
+    VirtIOS390Device *dev = VIRTIO_S390_DEVICE(obj);
+
+    object_property_add_link(obj, "rng", TYPE_RNG_BACKEND,
+                             (Object **)&dev->rng.rng, NULL);
+}
+
+static void s390_virtio_rng_class_init(ObjectClass *klass, void *data)
+{
+    VirtIOS390DeviceClass *k = VIRTIO_S390_DEVICE_CLASS(klass);
+
+    k->init = s390_virtio_rng_init;
+}
+
+static TypeInfo s390_virtio_rng = {
+    .name          = "virtio-rng-s390",
+    .parent        = TYPE_VIRTIO_S390_DEVICE,
+    .instance_size = sizeof(VirtIOS390Device),
+    .instance_init = s390_virtio_rng_initfn,
+    .class_init    = s390_virtio_rng_class_init,
+};
+
 static int s390_virtio_busdev_init(DeviceState *dev)
 {
     VirtIOS390Device *_dev = (VirtIOS390Device *)dev;
@@ -528,6 +564,7 @@ static void s390_virtio_register_types(void)
     type_register_static(&s390_virtio_blk);
     type_register_static(&s390_virtio_net);
     type_register_static(&s390_virtio_scsi);
+    type_register_static(&s390_virtio_rng);
     type_register_static(&s390_virtio_bridge_info);
 }
 

hw/s390-virtio-bus.h

@@ -19,6 +19,7 @@
 
 #include "virtio-blk.h"
 #include "virtio-net.h"
+#include "virtio-rng.h"
 #include "virtio-serial.h"
 #include "virtio-scsi.h"
 
@@ -75,6 +76,7 @@ struct VirtIOS390Device {
     virtio_serial_conf serial;
     virtio_net_conf net;
     VirtIOSCSIConf scsi;
+    VirtIORNGConf rng;
 };
 
 typedef struct VirtIOS390Bus {

hw/virtio-pci.c

@@ -852,6 +852,28 @@ static void virtio_balloon_exit_pci(PCIDevice *pci_dev)
     virtio_exit_pci(pci_dev);
 }
 
+static int virtio_rng_init_pci(PCIDevice *pci_dev)
+{
+    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+    VirtIODevice *vdev;
+
+    vdev = virtio_rng_init(&pci_dev->qdev, &proxy->rng);
+    if (!vdev) {
+        return -1;
+    }
+    virtio_init_pci(proxy, vdev);
+    return 0;
+}
+
+static void virtio_rng_exit_pci(PCIDevice *pci_dev)
+{
+    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+
+    virtio_pci_stop_ioeventfd(proxy);
+    virtio_rng_exit(proxy->vdev);
+    virtio_exit_pci(pci_dev);
+}
+
 static Property virtio_blk_properties[] = {
     DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
     DEFINE_BLOCK_PROPERTIES(VirtIOPCIProxy, blk.conf),
@@ -982,6 +1004,43 @@ static TypeInfo virtio_balloon_info = {
     .class_init    = virtio_balloon_class_init,
 };
 
+static void virtio_rng_initfn(Object *obj)
+{
+    PCIDevice *pci_dev = PCI_DEVICE(obj);
+    VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
+
+    object_property_add_link(obj, "rng", TYPE_RNG_BACKEND,
+                             (Object **)&proxy->rng.rng, NULL);
+}
+
+static Property virtio_rng_properties[] = {
+    DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
+static void virtio_rng_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
+
+    k->init = virtio_rng_init_pci;
+    k->exit = virtio_rng_exit_pci;
+    k->vendor_id = PCI_VENDOR_ID_REDHAT_QUMRANET;
+    k->device_id = PCI_DEVICE_ID_VIRTIO_RNG;
+    k->revision = VIRTIO_PCI_ABI_VERSION;
+    k->class_id = PCI_CLASS_OTHERS;
+    dc->reset = virtio_pci_reset;
+    dc->props = virtio_rng_properties;
+}
+
+static TypeInfo virtio_rng_info = {
+    .name          = "virtio-rng-pci",
+    .parent        = TYPE_PCI_DEVICE,
+    .instance_size = sizeof(VirtIOPCIProxy),
+    .instance_init = virtio_rng_initfn,
+    .class_init    = virtio_rng_class_init,
+};
+
 static int virtio_scsi_init_pci(PCIDevice *pci_dev)
 {
     VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
@@ -1046,6 +1105,7 @@ static void virtio_pci_register_types(void)
     type_register_static(&virtio_serial_info);
     type_register_static(&virtio_balloon_info);
     type_register_static(&virtio_scsi_info);
+    type_register_static(&virtio_rng_info);
 }
 
 type_init(virtio_pci_register_types)

hw/virtio-pci.h

@@ -17,6 +17,7 @@
 
 #include "virtio-blk.h"
 #include "virtio-net.h"
+#include "virtio-rng.h"
 #include "virtio-serial.h"
 #include "virtio-scsi.h"
 
@@ -46,6 +47,7 @@ typedef struct {
     virtio_serial_conf serial;
     virtio_net_conf net;
     VirtIOSCSIConf scsi;
+    VirtIORNGConf rng;
     bool ioeventfd_disabled;
     bool ioeventfd_started;
     VirtIOIRQFD *vector_irqfd;

hw/virtio-rng.c

@@ -0,0 +1,211 @@
+/*
+ * A virtio device implementing a hardware random number generator.
+ *
+ * Copyright 2012 Red Hat, Inc.
+ * Copyright 2012 Amit Shah <amit.shah@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 "iov.h"
+#include "qdev.h"
+#include "virtio.h"
+#include "virtio-rng.h"
+#include "qemu/rng.h"
+
+typedef struct VirtIORNG {
+    VirtIODevice vdev;
+
+    DeviceState *qdev;
+
+    /* Only one vq - guest puts buffer(s) on it when it needs entropy */
+    VirtQueue *vq;
+    VirtQueueElement elem;
+
+    /* Config data for the device -- currently only chardev */
+    VirtIORNGConf *conf;
+
+    /* Whether we've popped a vq element into 'elem' above */
+    bool popped;
+
+    RngBackend *rng;
+} VirtIORNG;
+
+static bool is_guest_ready(VirtIORNG *vrng)
+{
+    if (virtio_queue_ready(vrng->vq)
+        && (vrng->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+        return true;
+    }
+    return false;
+}
+
+static size_t pop_an_elem(VirtIORNG *vrng)
+{
+    size_t size;
+
+    if (!vrng->popped && !virtqueue_pop(vrng->vq, &vrng->elem)) {
+        return 0;
+    }
+    vrng->popped = true;
+
+    size = iov_size(vrng->elem.in_sg, vrng->elem.in_num);
+    return size;
+}
+
+/* Send data from a char device over to the guest */
+static void chr_read(void *opaque, const void *buf, size_t size)
+{
+    VirtIORNG *vrng = opaque;
+    size_t len;
+    int offset;
+
+    if (!is_guest_ready(vrng)) {
+        return;
+    }
+
+    offset = 0;
+    while (offset < size) {
+        if (!pop_an_elem(vrng)) {
+            break;
+        }
+        len = iov_from_buf(vrng->elem.in_sg, vrng->elem.in_num,
+                           0, buf + offset, size - offset);
+        offset += len;
+
+        virtqueue_push(vrng->vq, &vrng->elem, len);
+        vrng->popped = false;
+    }
+    virtio_notify(&vrng->vdev, vrng->vq);
+
+    /*
+     * Lastly, if we had multiple elems queued by the guest, and we
+     * didn't have enough data to fill them all, indicate we want more
+     * data.
+     */
+    len = pop_an_elem(vrng);
+    if (len) {
+        rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
+    }
+}
+
+static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
+    size_t size;
+
+    size = pop_an_elem(vrng);
+    if (size) {
+        rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
+    }
+}
+
+static uint32_t get_features(VirtIODevice *vdev, uint32_t f)
+{
+    return f;
+}
+
+static void virtio_rng_save(QEMUFile *f, void *opaque)
+{
+    VirtIORNG *vrng = opaque;
+
+    virtio_save(&vrng->vdev, f);
+
+    qemu_put_byte(f, vrng->popped);
+    if (vrng->popped) {
+        int i;
+
+        qemu_put_be32(f, vrng->elem.index);
+
+        qemu_put_be32(f, vrng->elem.in_num);
+        for (i = 0; i < vrng->elem.in_num; i++) {
+            qemu_put_be64(f, vrng->elem.in_addr[i]);
+        }
+
+        qemu_put_be32(f, vrng->elem.out_num);
+        for (i = 0; i < vrng->elem.out_num; i++) {
+            qemu_put_be64(f, vrng->elem.out_addr[i]);
+        }
+    }
+}
+
+static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIORNG *vrng = opaque;
+
+    if (version_id != 1) {
+        return -EINVAL;
+    }
+    virtio_load(&vrng->vdev, f);
+
+    vrng->popped = qemu_get_byte(f);
+    if (vrng->popped) {
+        int i;
+
+        vrng->elem.index = qemu_get_be32(f);
+
+        vrng->elem.in_num = qemu_get_be32(f);
+        g_assert(vrng->elem.in_num < VIRTQUEUE_MAX_SIZE);
+        for (i = 0; i < vrng->elem.in_num; i++) {
+            vrng->elem.in_addr[i] = qemu_get_be64(f);
+        }
+
+        vrng->elem.out_num = qemu_get_be32(f);
+        g_assert(vrng->elem.out_num < VIRTQUEUE_MAX_SIZE);
+        for (i = 0; i < vrng->elem.out_num; i++) {
+            vrng->elem.out_addr[i] = qemu_get_be64(f);
+        }
+
+        virtqueue_map_sg(vrng->elem.in_sg, vrng->elem.in_addr,
+                         vrng->elem.in_num, 1);
+        virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr,
+                         vrng->elem.out_num, 0);
+    }
+    return 0;
+}
+
+VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
+{
+    VirtIORNG *vrng;
+    VirtIODevice *vdev;
+    Error *local_err = NULL;
+
+    vdev = virtio_common_init("virtio-rng", VIRTIO_ID_RNG, 0,
+                              sizeof(VirtIORNG));
+
+    vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
+
+    vrng->rng = conf->rng;
+    if (vrng->rng == NULL) {
+        qerror_report(QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object");
+        return NULL;
+    }
+
+    rng_backend_open(vrng->rng, &local_err);
+    if (local_err) {
+        qerror_report_err(local_err);
+        error_free(local_err);
+        return NULL;
+    }
+
+    vrng->vq = virtio_add_queue(vdev, 8, handle_input);
+    vrng->vdev.get_features = get_features;
+
+    vrng->qdev = dev;
+    vrng->conf = conf;
+    vrng->popped = false;
+    register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save,
+                    virtio_rng_load, vrng);
+
+    return vdev;
+}
+
+void virtio_rng_exit(VirtIODevice *vdev)
+{
+    VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
+
+    unregister_savevm(vrng->qdev, "virtio-rng", vrng);
+    virtio_cleanup(vdev);
+}

hw/virtio-rng.h

@@ -0,0 +1,24 @@
+/*
+ * Virtio RNG Support
+ *
+ * Copyright Red Hat, Inc. 2012
+ * Copyright Amit Shah <amit.shah@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_RNG_H
+#define _QEMU_VIRTIO_RNG_H
+
+#include "qemu/rng.h"
+
+/* The Virtio ID for the virtio rng device */
+#define VIRTIO_ID_RNG    4
+
+struct VirtIORNGConf {
+    RngBackend *rng;
+};
+
+#endif

hw/virtio.h

@@ -203,6 +203,8 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, virtio_serial_conf *serial);
 VirtIODevice *virtio_balloon_init(DeviceState *dev);
 typedef struct VirtIOSCSIConf VirtIOSCSIConf;
 VirtIODevice *virtio_scsi_init(DeviceState *dev, VirtIOSCSIConf *conf);
+typedef struct VirtIORNGConf VirtIORNGConf;
+VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf);
 #ifdef CONFIG_LINUX
 VirtIODevice *virtio_9p_init(DeviceState *dev, V9fsConf *conf);
 #endif
@@ -213,6 +215,7 @@ void virtio_blk_exit(VirtIODevice *vdev);
 void virtio_serial_exit(VirtIODevice *vdev);
 void virtio_balloon_exit(VirtIODevice *vdev);
 void virtio_scsi_exit(VirtIODevice *vdev);
+void virtio_rng_exit(VirtIODevice *vdev);
 
 #define DEFINE_VIRTIO_COMMON_FEATURES(_state, _field) \
 	DEFINE_PROP_BIT("indirect_desc", _state, _field, \