include/linux/virtio_pci.h

   1 /*
   2  * Virtio PCI driver
   3  *
   4  * This module allows virtio devices to be used over a virtual PCI device.
   5  * This can be used with QEMU based VMMs like KVM or Xen.
   6  *
   7  * Copyright IBM Corp. 2007
   8  *
   9  * Authors:
  10  *  Anthony Liguori  <aliguori@us.ibm.com>
  11  *
  12  * This header is BSD licensed so anyone can use the definitions to implement
  13  * compatible drivers/servers.
  14  */
  15
  16 #ifndef _LINUX_VIRTIO_PCI_H
  17 #define _LINUX_VIRTIO_PCI_H
  18
  19 #include <linux/virtio_config.h>
  20
  21 /* A 32-bit r/o bitmask of the features supported by the host */
  22 #define VIRTIO_PCI_HOST_FEATURES        0
  23
  24 /* A 32-bit r/w bitmask of features activated by the guest */
  25 #define VIRTIO_PCI_GUEST_FEATURES       4
  26
  27 /* A 32-bit r/w PFN for the currently selected queue */
  28 #define VIRTIO_PCI_QUEUE_PFN            8
  29
  30 /* A 16-bit r/o queue size for the currently selected queue */
  31 #define VIRTIO_PCI_QUEUE_NUM            12
  32
  33 /* A 16-bit r/w queue selector */
  34 #define VIRTIO_PCI_QUEUE_SEL            14
  35
  36 /* A 16-bit r/w queue notifier */
  37 #define VIRTIO_PCI_QUEUE_NOTIFY         16
  38
  39 /* An 8-bit device status register.  */
  40 #define VIRTIO_PCI_STATUS               18
  41
  42 /* An 8-bit r/o interrupt status register.  Reading the value will return the
  43  * current contents of the ISR and will also clear it.  This is effectively
  44  * a read-and-acknowledge. */
  45 #define VIRTIO_PCI_ISR                  19
  46
  47 /* The bit of the ISR which indicates a device configuration change. */
  48 #define VIRTIO_PCI_ISR_CONFIG           0x2
  49
  50 /* MSI-X registers: only enabled if MSI-X is enabled. */
  51 /* A 16-bit vector for configuration changes. */
  52 #define VIRTIO_MSI_CONFIG_VECTOR        20
  53 /* A 16-bit vector for selected queue notifications. */
  54 #define VIRTIO_MSI_QUEUE_VECTOR         22
  55 /* Vector value used to disable MSI for queue */
  56 #define VIRTIO_MSI_NO_VECTOR            0xffff
  57
  58 /* The remaining space is defined by each driver as the per-driver
  59  * configuration space */
  60 #define VIRTIO_PCI_CONFIG(dev)          ((dev)->msix_enabled ? 24 : 20)
  61
  62 /* Virtio ABI version, this must match exactly */
  63 #define VIRTIO_PCI_ABI_VERSION          0
  64
  65 /* How many bits to shift physical queue address written to QUEUE_PFN.
  66  * 12 is historical, and due to x86 page size. */
  67 #define VIRTIO_PCI_QUEUE_ADDR_SHIFT     12
  68
  69 /* The alignment to use between consumer and producer parts of vring.
  70  * x86 pagesize again. */
  71 #define VIRTIO_PCI_VRING_ALIGN          4096
  72 #endif