Linux Virtualization - Dec 2007 - [kvm-devel] [Virtio-for-kvm] [PATCH 05/13] [Mostly resend] virtio additions

From c8a8b56ccb6e12954b4752fd8ca46850fe354741 Mon Sep 17 00:00:00 2001
From: Anthony Liguori <aliguori@us.ibm.com>
Date: Mon, 12 Nov 2007 21:30:26 -0600
Subject: [PATCH] virtio: PCI device

This is a PCI device that implements a transport for virtio.  It allows 
virtio
devices to be used by QEMU based VMMs like KVM or Xen.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 drivers/virtio/Kconfig      |   17 ++
 drivers/virtio/Makefile     |    1 +
 drivers/virtio/virtio_pci.c |  414 
+++++++++++++++++++++++++++++++++++++++++++
 include/linux/virtio_pci.h  |   52 ++++++
 4 files changed, 484 insertions(+), 0 deletions(-)
 create mode 100644 drivers/virtio/virtio_pci.c
 create mode 100644 include/linux/virtio_pci.h

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 9e33fc4..73a414c 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -6,3 +6,20 @@ config VIRTIO
 config VIRTIO_RING
     bool
     depends on VIRTIO
+
+config VIRTIO_PCI
+    tristate "PCI driver for virtio devices (EXPERIMENTAL)"
+    depends on PCI && EXPERIMENTAL
+    select VIRTIO
+    select VIRTIO_RING
+    ---help---
+      This drivers provides support for virtio based paravirtual device
+      drivers over PCI.  This requires that your VMM has appropriate PCI
+      virtio backends.  Most QEMU based VMMs should support these devices
+      (like KVM or Xen).
+
+      Currently, the ABI is not considered stable so there is no guarantee
+      that this version of the driver will work with your VMM.
+
+      If unsure, say M.
+
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index f70e409..cc84999 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -1,2 +1,3 @@
 obj-$(CONFIG_VIRTIO) += virtio.o
 obj-$(CONFIG_VIRTIO_RING) += virtio_ring.o
+obj-$(CONFIG_VIRTIO_PCI) += virtio_pci.o
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
new file mode 100644
index 0000000..7118215
--- /dev/null
+++ b/drivers/virtio/virtio_pci.c
@@ -0,0 +1,414 @@
+/*
+ * Virtio PCI driver
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/list.h>
+#include <linux/pci.h>
+#include <linux/interrupt.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_ring.h>
+#include <linux/virtio_pci.h>
+#include <linux/highmem.h>
+#include <linux/spinlock.h>
+
+MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
+MODULE_DESCRIPTION("virtio-pci");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("1");
+
+/* Our device structure */
+struct virtio_pci_device
+{
+    struct virtio_device vdev;
+    struct pci_dev *pci_dev;
+
+    /* the IO mapping for the PCI config space */
+    void *ioaddr;
+
+    /* a list of queues so we can dispatch IRQs */
+    spinlock_t lock;
+    struct list_head virtqueues;
+};
+
+struct virtio_pci_vq_info
+{
+    /* the actual virtqueue */
+    struct virtqueue *vq;
+
+    /* the number of entries in the queue */
+    int num;
+
+    /* the index of the queue */
+    int queue_index;
+
+    /* the virtual address of the ring queue */
+    void *queue;
+
+    /* the list node for the virtqueues list */
+    struct list_head node;
+};
+
+/* We have to enumerate here all virtio PCI devices. */
+static struct pci_device_id virtio_pci_id_table[] = {
+    { 0x1AF4, 0x1000, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
+    { 0x1AF4, 0x1001, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
+    { 0x1AF4, 0x1002, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 }, /* Dummy entry */
+    { 0 },
+};
+
+MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);
+
+/* A PCI device has it's own struct device and so does a virtio device so
+ * we create a place for the virtio devices to show up in sysfs.  I 
think it
+ * would make more sense for virtio to not insist on having it's own 
device. */
+static struct device virtio_pci_root = {
+    .parent        = NULL,
+    .bus_id        = "virtio-pci",
+};
+
+/* Unique numbering for devices under the kvm root */
+static unsigned int dev_index;
+
+/* Convert a generic virtio device to our structure */
+static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
+{
+    return container_of(vdev, struct virtio_pci_device, vdev);
+}
+
+/* virtio config->feature() implementation */
+static bool vp_feature(struct virtio_device *vdev, unsigned bit)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    u32 mask;
+
+    /* Since this function is supposed to have the side effect of
+     * enabling a queried feature, we simulate that by doing a read
+     * from the host feature bitmask and then writing to the guest
+     * feature bitmask */
+    mask = ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
+    if (mask & (1 << bit)) {
+        mask |= (1 << bit);
+        iowrite32(mask, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+    }
+
+    return !!(mask & (1 << bit));
+}
+
+/* virtio config->get() implementation */
+static void vp_get(struct virtio_device *vdev, unsigned offset,
+           void *buf, unsigned len)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    void *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
+    u8 *ptr = buf;
+    int i;
+
+    for (i = 0; i < len; i++)
+        ptr[i] = ioread8(ioaddr + i);
+}
+
+/* the config->set() implementation.  it's symmetric to the
config->get()
+ * implementation */
+static void vp_set(struct virtio_device *vdev, unsigned offset,
+           const void *buf, unsigned len)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    void *ioaddr = vp_dev->ioaddr + VIRTIO_PCI_CONFIG + offset;
+    const u8 *ptr = buf;
+    int i;
+
+    for (i = 0; i < len; i++)
+        iowrite8(ptr[i], ioaddr + i);
+}
+
+/* config->{get,set}_status() implementations */
+static u8 vp_get_status(struct virtio_device *vdev)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    return ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+}
+
+static void vp_set_status(struct virtio_device *vdev, u8 status)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    return iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+}
+
+/* the notify function used when creating a virt queue */
+static void vp_notify(struct virtqueue *vq)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+    struct virtio_pci_vq_info *info = vq->priv;
+
+    /* we write the queue's selector into the notification register to
+     * signal the other end */
+    iowrite16(info->queue_index, vp_dev->ioaddr +
VIRTIO_PCI_QUEUE_NOTIFY);
+}
+
+/* A small wrapper to also acknowledge the interrupt when it's handled.
+ * I really need an EIO hook for the vring so I can ack the interrupt 
once we
+ * know that we'll be handling the IRQ but before we invoke the 
callback since
+ * the callback may notify the host which results in the host attempting to
+ * raise an interrupt that we would then mask once we acknowledged the
+ * interrupt. */
+static irqreturn_t vp_interrupt(int irq, void *opaque)
+{
+    struct virtio_pci_device *vp_dev = opaque;
+    struct virtio_pci_vq_info *info;
+    irqreturn_t ret = IRQ_NONE;
+    u8 isr;
+
+    /* reading the ISR has the effect of also clearing it so it's very
+     * important to save off the value. */
+    isr = ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
+
+    /* It's definitely not us if the ISR was not high */
+    if (!isr)
+        return IRQ_NONE;
+
+    spin_lock(&vp_dev->lock);
+    list_for_each_entry(info, &vp_dev->virtqueues, node) {
+        if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)
+            ret = IRQ_HANDLED;
+    }
+    spin_unlock(&vp_dev->lock);
+
+    return ret;
+}
+
+/* the config->find_vq() implementation */
+static struct virtqueue *vp_find_vq(struct virtio_device *vdev, 
unsigned index,
+                    bool (*callback)(struct virtqueue *vq))
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+    struct virtio_pci_vq_info *info;
+    struct virtqueue *vq;
+    u16 num;
+    int err;
+
+    /* Select the queue we're interested in */
+    iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+
+    /* Check if queue is either not available or already active. */
+    num = ioread16(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
+    if (!num || ioread32(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN))
+        return ERR_PTR(-ENOENT);
+
+    /* allocate and fill out our structure the represents an active
+     * queue */
+    info = kmalloc(sizeof(struct virtio_pci_vq_info), GFP_KERNEL);
+    if (!info)
+        return ERR_PTR(-ENOMEM);
+
+    info->queue_index = index;
+    info->num = num;
+
+    info->queue = kzalloc(PAGE_ALIGN(vring_size(num,PAGE_SIZE)), 
GFP_KERNEL);
+    if (info->queue == NULL) {
+        err = -ENOMEM;
+        goto out_info;
+    }
+
+    /* activate the queue */
+    iowrite32(virt_to_phys(info->queue) >> PAGE_SHIFT,
+          vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+
+    /* create the vring */
+    vq = vring_new_virtqueue(info->num, vdev, info->queue,
+                 vp_notify, callback);
+    if (!vq) {
+        err = -ENOMEM;
+        goto out_activate_queue;
+    }
+
+    vq->priv = info;
+    info->vq = vq;
+
+    list_add(&info->node, &vp_dev->virtqueues);
+
+    return vq;
+
+out_activate_queue:
+    iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+    kfree(info->queue);
+out_info:
+    kfree(info);
+    return ERR_PTR(err);
+}
+
+/* the config->del_vq() implementation */
+static void vp_del_vq(struct virtqueue *vq)
+{
+    struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+    struct virtio_pci_vq_info *info = vq->priv;
+
+    list_del(&info->node);
+
+    vring_del_virtqueue(vq);
+
+    /* Select and deactivate the queue */
+    iowrite16(info->queue_index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
+    iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+
+    kfree(info->queue);
+    kfree(info);
+}
+
+static struct virtio_config_ops virtio_pci_config_ops = {
+    .feature    = vp_feature,
+    .get        = vp_get,
+    .set        = vp_set,
+    .get_status    = vp_get_status,
+    .set_status    = vp_set_status,
+    .find_vq    = vp_find_vq,
+    .del_vq        = vp_del_vq,
+};
+
+/* the PCI probing function */
+static int __devinit virtio_pci_probe(struct pci_dev *pci_dev,
+                      const struct pci_device_id *id)
+{
+    struct virtio_pci_device *vp_dev;
+    int err;
+
+    /* allocate our structure and fill it out */
+    vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
+    if (vp_dev == NULL)
+        return -ENOMEM;
+
+    snprintf(vp_dev->vdev.dev.bus_id, BUS_ID_SIZE, "virtio%d",
dev_index);
+    vp_dev->vdev.index = dev_index;
+    dev_index++;
+
+    vp_dev->vdev.dev.parent = &virtio_pci_root;
+    vp_dev->vdev.config = &virtio_pci_config_ops;
+    vp_dev->pci_dev = pci_dev;
+    INIT_LIST_HEAD(&vp_dev->virtqueues);
+    spin_lock_init(&vp_dev->lock);
+
+    /* enable the device */
+    err = pci_enable_device(pci_dev);
+    if (err)
+        goto out;
+
+    err = pci_request_regions(pci_dev, "virtio-pci");
+    if (err)
+        goto out_enable_device;
+
+    vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
+    if (vp_dev->ioaddr == NULL)
+        goto out_req_regions;
+
+    pci_set_drvdata(pci_dev, vp_dev);
+
+    /* we use the subsystem vendor/device id as the virtio vendor/device
+     * id.  this allows us to use the same PCI vendor/device id for all
+     * virtio devices and to identify the particular virtio driver by
+     * the subsytem ids */
+    vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
+    vp_dev->vdev.id.device = pci_dev->subsystem_device;
+
+    /* register a handler for the queue with the PCI device's interrupt */
+    err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
+              vp_dev->vdev.dev.bus_id, vp_dev);
+    if (err)
+        goto out_set_drvdata;
+
+    /* finally register the virtio device */
+    err = register_virtio_device(&vp_dev->vdev);
+    if (err)
+        goto out_req_irq;
+
+    return 0;
+
+out_req_irq:
+    free_irq(pci_dev->irq, vp_dev);
+out_set_drvdata:
+    pci_set_drvdata(pci_dev, NULL);
+    pci_iounmap(pci_dev, vp_dev->ioaddr);
+out_req_regions:
+    pci_release_regions(pci_dev);
+out_enable_device:
+    pci_disable_device(pci_dev);
+out:
+    kfree(vp_dev);
+    return err;
+}
+
+static void __devexit virtio_pci_remove(struct pci_dev *pci_dev)
+{
+    struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+
+    free_irq(pci_dev->irq, vp_dev);
+    pci_set_drvdata(pci_dev, NULL);
+    pci_iounmap(pci_dev, vp_dev->ioaddr);
+    pci_release_regions(pci_dev);
+    pci_disable_device(pci_dev);
+    kfree(vp_dev);
+}
+
+#ifdef CONFIG_PM
+static int virtio_pci_suspend(struct pci_dev *pci_dev, pm_message_t state)
+{
+    pci_save_state(pci_dev);
+    pci_set_power_state(pci_dev, PCI_D3hot);
+    return 0;
+}
+
+static int virtio_pci_resume(struct pci_dev *pci_dev)
+{
+    pci_restore_state(pci_dev);
+    pci_set_power_state(pci_dev, PCI_D0);
+    return 0;
+}
+#endif
+
+static struct pci_driver virtio_pci_driver = {
+    .name        = "virtio-pci",
+    .id_table    = virtio_pci_id_table,
+    .probe        = virtio_pci_probe,
+    .remove        = virtio_pci_remove,
+#ifdef CONFIG_PM
+    .suspend    = virtio_pci_suspend,
+    .resume        = virtio_pci_resume,
+#endif
+};
+
+static int __init virtio_pci_init(void)
+{
+    int err;
+
+    err = device_register(&virtio_pci_root);
+    if (err)
+        return err;
+
+    err = pci_register_driver(&virtio_pci_driver);
+    if (err)
+        device_unregister(&virtio_pci_root);
+
+    return err;
+}
+
+module_init(virtio_pci_init);
+
+static void __exit virtio_pci_exit(void)
+{
+    device_unregister(&virtio_pci_root);
+    pci_unregister_driver(&virtio_pci_driver);
+}
+
+module_exit(virtio_pci_exit);
diff --git a/include/linux/virtio_pci.h b/include/linux/virtio_pci.h
new file mode 100644
index 0000000..4b28409
--- /dev/null
+++ b/include/linux/virtio_pci.h
@@ -0,0 +1,52 @@
+/*
+ * Virtio PCI driver
+ *
+ * This module allows virtio devices to be used over a virtual PCI device.
+ * This can be used with QEMU based VMMs like KVM or Xen.
+ *
+ * Copyright IBM Corp. 2007
+ *
+ * Authors:
+ *  Anthony Liguori  <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef _LINUX_VIRTIO_PCI_H
+#define _LINUX_VIRTIO_PCI_H
+
+#include <linux/virtio_config.h>
+
+/* A 32-bit r/o bitmask of the features supported by the host */
+#define VIRTIO_PCI_HOST_FEATURES    0
+
+/* A 32-bit r/w bitmask of features activated by the guest */
+#define VIRTIO_PCI_GUEST_FEATURES    4
+
+/* A 32-bit r/w PFN for the currently selected queue */
+#define VIRTIO_PCI_QUEUE_PFN        8
+
+/* A 16-bit r/o queue size for the currently selected queue */
+#define VIRTIO_PCI_QUEUE_NUM        12
+
+/* A 16-bit r/w queue selector */
+#define VIRTIO_PCI_QUEUE_SEL        14
+
+/* A 16-bit r/w queue notifier */
+#define VIRTIO_PCI_QUEUE_NOTIFY        16
+
+/* An 8-bit device status register.  */
+#define VIRTIO_PCI_STATUS        18
+
+/* An 8-bit r/o interrupt status register.  Reading the value will 
return the
+ * current contents of the ISR and will also clear it.  This is effectively
+ * a read-and-acknowledge. */
+#define VIRTIO_PCI_ISR            19
+
+/* The remaining space is defined by each driver as the per-driver
+ * configuration space */
+#define VIRTIO_PCI_CONFIG        20
+
+#endif
-- 
1.5.3.3