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>

4 files changed, 513 insertions, 0 deletions

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index de0c8c2654ef..833db2f36e9b 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -6,3 +6,20 @@ config VIRTIO
 config VIRTIO_RING
         tristate
         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 f70e40971dd9..cc84999f3057 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 000000000000..192687e3a56a
--- /dev/null
+++ b/drivers/virtio/virtio_pci.c
@@ -0,0 +1,440 @@
+/*
+ * 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 or later.
+ * 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;
+};
+
+/* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
+static struct pci_device_id virtio_pci_id_table[] = {
+        { 0x1af4, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0 },
+        { 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);
+        /* We should never be setting status to 0. */
+        BUG_ON(status == 0);
+        return iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
+}
+
+static void vp_reset(struct virtio_device *vdev)
+{
+        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+        /* 0 status means a reset. */
+        return iowrite8(0, 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;
+
+        /* Configuration change?  Tell driver if it wants to know. */
+        if (isr & VIRTIO_PCI_ISR_CONFIG) {
+                struct virtio_driver *drv;
+                drv = container_of(vp_dev->vdev.dev.driver,
+                                   struct virtio_driver, driver);
+
+                if (drv->config_changed)
+                        drv->config_changed(&vp_dev->vdev);
+        }
+
+        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,
+                                    void (*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;
+
+        spin_lock(&vp_dev->lock);
+        list_add(&info->node, &vp_dev->virtqueues);
+        spin_unlock(&vp_dev->lock);
+
+        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;
+
+        spin_lock(&vp_dev->lock);
+        list_del(&info->node);
+        spin_unlock(&vp_dev->lock);
+
+        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,
+        .reset          = vp_reset,
+        .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;
+
+        /* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
+        if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
+                return -ENODEV;
+
+        /* 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 000000000000..860eb37bfa07
--- /dev/null
+++ b/include/linux/virtio_pci.h
@@ -0,0 +1,55 @@
+/*
+ * 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 or later.
+ * 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 bit of the ISR which indicates a device configuration change. */
+#define VIRTIO_PCI_ISR_CONFIG           0x2
+
+/* The remaining space is defined by each driver as the per-driver
+ * configuration space */
+#define VIRTIO_PCI_CONFIG               20
+
+#endif