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acrn-hypervisor/devicemodel/include/virtio.h

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/*-
* Copyright (c) 2013 Chris Torek <torek @ torek net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD$
*/
/**
* @file virtio.h
*
* @brief Virtio Backend Service (VBS) APIs for ACRN Project
*/
#ifndef _VIRTIO_H_
#define _VIRTIO_H_
/*
* These are derived from several virtio specifications.
*
* Some useful links:
* https://github.com/rustyrussell/virtio-spec
* http://people.redhat.com/pbonzini/virtio-spec.pdf
*/
/*
* A virtual device has zero or more "virtual queues" (virtqueue).
* Each virtqueue uses at least two 4096-byte pages, laid out thus:
*
* +-----------------------------------------------+
* | "desc": <N> descriptors, 16 bytes each |
* | ----------------------------------------- |
* | "avail": 2 uint16; <N> uint16; 1 uint16 |
* | ----------------------------------------- |
* | pad to 4k boundary |
* +-----------------------------------------------+
* | "used": 2 x uint16; <N> elems; 1 uint16 |
* | ----------------------------------------- |
* | pad to 4k boundary |
* +-----------------------------------------------+
*
* The number <N> that appears here is always a power of two and is
* limited to no more than 32768 (as it must fit in a 16-bit field).
* If <N> is sufficiently large, the above will occupy more than
* two pages. In any case, all pages must be physically contiguous
* within the guest's physical address space.
*
* The <N> 16-byte "desc" descriptors consist of a 64-bit guest
* physical address <addr>, a 32-bit length <len>, a 16-bit
* <flags>, and a 16-bit <next> field (all in guest byte order).
*
* There are three flags that may be set :
* NEXT descriptor is chained, so use its "next" field
* WRITE descriptor is for host to write into guest RAM
* (else host is to read from guest RAM)
* INDIRECT descriptor address field is (guest physical)
* address of a linear array of descriptors
*
* Unless INDIRECT is set, <len> is the number of bytes that may
* be read/written from guest physical address <addr>. If
* INDIRECT is set, WRITE is ignored and <len> provides the length
* of the indirect descriptors (and <len> must be a multiple of
* 16). Note that NEXT may still be set in the main descriptor
* pointing to the indirect, and should be set in each indirect
* descriptor that uses the next descriptor (these should generally
* be numbered sequentially). However, INDIRECT must not be set
* in the indirect descriptors. Upon reaching an indirect descriptor
* without a NEXT bit, control returns to the direct descriptors.
*
* Except inside an indirect, each <next> value must be in the
* range [0 .. N) (i.e., the half-open interval). (Inside an
* indirect, each <next> must be in the range [0 .. <len>/16).)
*
* The "avail" data structures reside in the same pages as the
* "desc" structures since both together are used by the device to
* pass information to the hypervisor's virtual driver. These
* begin with a 16-bit <flags> field and 16-bit index <idx>, then
* have <N> 16-bit <ring> values, followed by one final 16-bit
* field <used_event>. The <N> <ring> entries are simply indices
* indices into the descriptor ring (and thus must meet the same
* constraints as each <next> value). However, <idx> is counted
* up from 0 (initially) and simply wraps around after 65535; it
* is taken mod <N> to find the next available entry.
*
* The "used" ring occupies a separate page or pages, and contains
* values written from the virtual driver back to the guest OS.
* This begins with a 16-bit <flags> and 16-bit <idx>, then there
* are <N> "vring_used" elements, followed by a 16-bit <avail_event>.
* The <N> "vring_used" elements consist of a 32-bit <id> and a
* 32-bit <len> (tlen below). The <id> is simply the index of
* the head of a descriptor chain the guest made available
* earlier, and the <len> is the number of bytes actually written,
* e.g., in the case of a network driver that provided a large
* receive buffer but received only a small amount of data.
*
* The two event fields, <used_event> and <avail_event>, in the
* avail and used rings (respectively -- note the reversal!), are
* always provided, but are used only if the virtual device
* negotiates the VIRTIO_RING_F_EVENT_IDX feature during feature
* negotiation. Similarly, both rings provide a flag --
* ACRN_VRING_AVAIL_F_NO_INTERRUPT and ACRN_VRING_USED_F_NO_NOTIFY -- in
* their <flags> field, indicating that the guest does not need an
* interrupt, or that the hypervisor driver does not need a
* notify, when descriptors are added to the corresponding ring.
* (These are provided only for interrupt optimization and need
* not be implemented.)
*/
#include <linux/virtio_ring.h>
#include <linux/virtio_config.h>
#include <linux/virtio_pci.h>
#include "types.h"
#include "timer.h"
/**
* @brief virtio API
*
* @defgroup acrn_virtio virtio API
* @{
*/
enum {
BACKEND_UNKNOWN = 0,
BACKEND_VBSU,
BACKEND_VBSK,
BACKEND_VHOST,
BACKEND_MAX
};
/*
* The address of any given virtual queue is determined by a single
* Page Frame Number register. The guest writes the PFN into the
* PCI config space. However, a device that has two or more
* virtqueues can have a different PFN, and size, for each queue.
* The number of queues is determinable via the PCI config space
* VTCFG_R_QSEL register. Writes to QSEL select the queue: 0 means
* queue #0, 1 means queue#1, etc. Once a queue is selected, the
* remaining PFN and QNUM registers refer to that queue.
*
* QNUM is a read-only register containing a nonzero power of two
* that indicates the (hypervisor's) queue size. Or, if reading it
* produces zero, the hypervisor does not have a corresponding
* queue. (The number of possible queues depends on the virtual
* device. The block device has just one; the network device
* provides either two -- 0 = receive, 1 = transmit -- or three,
* with 2 = control.)
*
* PFN is a read/write register giving the physical page address of
* the virtqueue in guest memory (the guest must allocate enough space
* based on the hypervisor's provided QNUM).
*
* QNOTIFY is effectively write-only: when the guest writes a queue
* number to the register, the hypervisor should scan the specified
* virtqueue. (Reading QNOTIFY currently always gets 0).
*/
/*
* PFN register shift amount
*/
#define VRING_PAGE_BITS 12
/*
* Virtio device types
*/
#define VIRTIO_TYPE_NET 1
#define VIRTIO_TYPE_BLOCK 2
#define VIRTIO_TYPE_CONSOLE 3
#define VIRTIO_TYPE_ENTROPY 4
#define VIRTIO_TYPE_BALLOON 5
#define VIRTIO_TYPE_IOMEMORY 6
#define VIRTIO_TYPE_RPMSG 7
#define VIRTIO_TYPE_SCSI 8
#define VIRTIO_TYPE_9P 9
#define VIRTIO_TYPE_INPUT 18
/*
* ACRN virtio device types
* Experimental IDs start at 0xFFFF and work down
*/
#define VIRTIO_TYPE_RPMB 0xFFFF
#define VIRTIO_TYPE_HECI 0xFFFE
#define VIRTIO_TYPE_AUDIO 0xFFFD
#define VIRTIO_TYPE_IPU 0xFFFC
#define VIRTIO_TYPE_TSN 0xFFFB
#define VIRTIO_TYPE_HYPERDMABUF 0xFFFA
#define VIRTIO_TYPE_HDCP 0xFFF9
#define VIRTIO_TYPE_COREU 0xFFF8
#define VIRTIO_TYPE_GPIO 0xFFF7
#define VIRTIO_TYPE_I2C 0xFFF6
/*
* PCI vendor/device IDs
*/
#define INTEL_VENDOR_ID 0x8086
#define ORACLE_VENDOR_ID 0x108E
#define VIRTIO_VENDOR 0x1AF4
#define VIRTIO_DEV_NET 0x1000
#define VIRTIO_DEV_BLOCK 0x1001
#define VIRTIO_DEV_CONSOLE 0x1003
#define VIRTIO_DEV_RANDOM 0x1005
/*
* ACRN virtio device IDs
*/
#define VIRTIO_DEV_RPMB 0x8601
#define VIRTIO_DEV_HECI 0x8602
#define VIRTIO_DEV_AUDIO 0x8603
#define VIRTIO_DEV_IPU 0x8604
#define VIRTIO_DEV_TSN 0x8605
#define VIRTIO_DEV_HYPERDMABUF 0x8606
#define VIRTIO_DEV_HDCP 0x8607
#define VIRTIO_DEV_COREU 0x8608
#define VIRTIO_DEV_GPIO 0x8609
#define VIRTIO_DEV_I2C 0x860a
/*
* VIRTIO_CONFIG_S_NEEDS_RESET is not defined
* in some environments's virtio_config.h
*/
#ifndef VIRTIO_CONFIG_S_NEEDS_RESET
#define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
#endif
/*
* Bits in VIRTIO_PCI_ISR. These apply only if not using MSI-X.
*
* (We don't [yet?] ever use CONF_CHANGED.)
*/
#define VIRTIO_PCI_ISR_QUEUES 0x01
/* re-scan queues */
struct vmctx;
struct pci_vdev;
struct virtio_vq_info;
/*
* A virtual device, with some number (possibly 0) of virtual
* queues and some size (possibly 0) of configuration-space
* registers private to the device. The virtio_base should come
* at the front of each "derived class", so that a pointer to the
* virtio_base is also a pointer to the more specific, derived-
* from-virtio driver's virtio_base struct.
*
* Note: inside each hypervisor virtio driver, changes to these
* data structures must be locked against other threads, if any.
* Except for PCI config space register read/write, we assume each
* driver does the required locking, but we need a pointer to the
* lock (if there is one) for PCI config space read/write ops.
*
* When the guest reads or writes the device's config space, the
* generic layer checks for operations on the special registers
* described above. If the offset of the register(s) being read
* or written is past the CFG area (CFG0 or CFG1), the request is
* passed on to the virtual device, after subtracting off the
* generic-layer size. (So, drivers can just use the offset as
* an offset into "struct config", for instance.)
*
* (The virtio layer also makes sure that the read or write is to/
* from a "good" config offset, hence cfgsize, and on BAR #0.
* However, the driver must verify the read or write size and offset
* and that no one is writing a readonly register.)
*
* The BROKED flag ("this thing done gone and broked") is for future
* use.
*/
#define VIRTIO_USE_MSIX 0x01
#define VIRTIO_EVENT_IDX 0x02 /* use the event-index values */
#define VIRTIO_BROKED 0x08 /* ??? */
/*
* virtio pci device bar layout
* 0 : legacy PIO bar
* 1 : MSIX bar
* 2 : modern PIO bar, used as notify
* 4+5 : modern 64-bit MMIO bar
*
* pci bar layout for legacy/modern/transitional devices
* legacy : (0) + (1)
* modern (no pio notify) : (1) + (4+5)
* modern (with pio notify) : (1) + (2) + (4+5)
* transitional (no pio notify) : (0) + (1) + (4+5)
* transitional (with pio notify) : (0) + (1) + (2) + (4+5)
*/
#define VIRTIO_LEGACY_PIO_BAR_IDX 0
#define VIRTIO_MODERN_PIO_BAR_IDX 2
#define VIRTIO_MODERN_MMIO_BAR_IDX 4
/*
* region layout in modern mmio bar
* one 4KB region for one capability
*/
#define VIRTIO_CAP_COMMON_OFFSET 0x0000
#define VIRTIO_CAP_COMMON_SIZE 0x1000
#define VIRTIO_CAP_ISR_OFFSET 0x1000
#define VIRTIO_CAP_ISR_SIZE 0x1000
#define VIRTIO_CAP_DEVICE_OFFSET 0x2000
#define VIRTIO_CAP_DEVICE_SIZE 0x1000
#define VIRTIO_CAP_NOTIFY_OFFSET 0x3000
#define VIRTIO_CAP_NOTIFY_SIZE 0x1000
#define VIRTIO_MODERN_MEM_BAR_SIZE (VIRTIO_CAP_NOTIFY_OFFSET + \
VIRTIO_CAP_NOTIFY_SIZE)
/* 4-byte notify register for one virtqueue */
#define VIRTIO_MODERN_NOTIFY_OFF_MULT 4
/* Common configuration */
#define VIRTIO_PCI_CAP_COMMON_CFG 1
/* Notifications */
#define VIRTIO_PCI_CAP_NOTIFY_CFG 2
/* ISR access */
#define VIRTIO_PCI_CAP_ISR_CFG 3
/* Device specific configuration */
#define VIRTIO_PCI_CAP_DEVICE_CFG 4
/* PCI configuration access */
#define VIRTIO_PCI_CAP_PCI_CFG 5
/**
* @brief Base component to any virtio device
*/
struct virtio_base {
struct virtio_ops *vops; /**< virtio operations */
int flags; /**< VIRTIO_* flags from above */
pthread_mutex_t *mtx; /**< POSIX mutex, if any */
struct pci_vdev *dev; /**< PCI device instance */
uint64_t negotiated_caps; /**< negotiated capabilities */
uint64_t device_caps; /**< device capabilities */
struct virtio_vq_info *queues; /**< one per nvq */
int curq; /**< current queue */
uint8_t status; /**< value from last status write */
uint8_t isr; /**< ISR flags, if not MSI-X */
uint16_t msix_cfg_idx; /**< MSI-X vector for config event */
uint32_t legacy_pio_bar_idx; /**< index of legacy pio bar */
uint32_t modern_pio_bar_idx; /**< index of modern pio bar */
uint32_t modern_mmio_bar_idx; /**< index of modern mmio bar */
uint8_t config_generation; /**< configuration generation */
uint32_t device_feature_select; /**< current selected device feature */
uint32_t driver_feature_select; /**< current selected guest feature */
int cfg_coff; /**< PCI cfg access capability offset */
int backend_type; /**< VBSU, VBSK or VHOST */
struct acrn_timer polling_timer; /**< timer for polling mode */
int polling_in_progress; /**< The polling status */
};
#define VIRTIO_BASE_LOCK(vb) \
do { \
if (vb->mtx) \
pthread_mutex_lock(vb->mtx); \
} while (0)
#define VIRTIO_BASE_UNLOCK(vb) \
do { \
if (vb->mtx) \
pthread_mutex_unlock(vb->mtx); \
} while (0)
/**
* @brief Virtio specific operation functions for this type of virtio device
*/
struct virtio_ops {
const char *name; /**< name of driver (for diagnostics) */
int nvq; /**< number of virtual queues */
size_t cfgsize; /**< size of dev-specific config regs */
void (*reset)(void *);
/**< called on virtual device reset */
void (*qnotify)(void *, struct virtio_vq_info *);
/**< called on QNOTIFY if no VQ notify */
int (*cfgread)(void *, int, int, uint32_t *);
/**< to read config regs */
int (*cfgwrite)(void *, int, int, uint32_t);
/**< to write config regs */
void (*apply_features)(void *, uint64_t);
/**< to apply negotiated features */
void (*set_status)(void *, uint64_t);
/**< called to set device status */
};
#define VQ_ALLOC 0x01 /* set once we have a pfn */
#define VQ_BROKED 0x02 /* ??? */
/**
* @brief Virtqueue data structure
*
* Data structure allocated (statically) per virtual queue.
*
* Drivers may change qsize after a reset. When the guest OS
* requests a device reset, the hypervisor first calls
* vb->vo->reset(); then the data structure below is
* reinitialized (for each virtqueue: vb->vo->nvq).
*
* The remaining fields should only be fussed-with by the generic
* code.
*
* Note: the addresses of desc, avail, and vq_used are all
* computable from each other, but it's a lot simpler if we just
* keep a pointer to each one. The event indices are similarly
* (but more easily) computable, and this time we'll compute them:
* they're just XX_ring[N].
*/
struct virtio_vq_info {
uint16_t qsize; /**< size of this queue (a power of 2) */
void (*notify)(void *, struct virtio_vq_info *);
/**< called instead of notify, if not NULL */
struct virtio_base *base;
/**< backpointer to virtio_base */
uint16_t num; /**< the num'th queue in the virtio_base */
uint16_t flags; /**< flags (see above) */
uint16_t last_avail; /**< a recent value of avail->idx */
uint16_t save_used; /**< saved used->idx; see vq_endchains */
uint16_t msix_idx; /**< MSI-X index, or VIRTIO_MSI_NO_VECTOR */
uint32_t pfn; /**< PFN of virt queue (not shifted!) */
volatile struct vring_desc *desc;
/**< descriptor array */
volatile struct vring_avail *avail;
/**< the "avail" ring */
volatile struct vring_used *used;
/**< the "used" ring */
uint32_t gpa_desc[2]; /**< gpa of descriptors */
uint32_t gpa_avail[2]; /**< gpa of avail_ring */
uint32_t gpa_used[2]; /**< gpa of used_ring */
bool enabled; /**< whether the virtqueue is enabled */
};
/* as noted above, these are sort of backwards, name-wise */
#define VQ_AVAIL_EVENT_IDX(vq) \
(*(volatile uint16_t *)&(vq)->used->ring[(vq)->qsize])
#define VQ_USED_EVENT_IDX(vq) \
((vq)->avail->ring[(vq)->qsize])
/**
* @brief Is this ring ready for I/O?
*
* @param vq Pointer to struct virtio_vq_info.
*
* @return false on not ready and true on ready.
*/
static inline bool
vq_ring_ready(struct virtio_vq_info *vq)
{
return ((vq->flags & VQ_ALLOC) == VQ_ALLOC);
}
/**
* @brief Are there "available" descriptors?
*
* This does not count how many, just returns true if there is any.
*
* @param vq Pointer to struct virtio_vq_info.
*
* @return false on not available and true on available.
*/
static inline bool
vq_has_descs(struct virtio_vq_info *vq)
{
return (vq_ring_ready(vq) && vq->last_avail !=
vq->avail->idx);
}
/**
* @brief Deliver an interrupt to guest on the given virtqueue.
*
* The interrupt could be MSI-X or a generic MSI interrupt.
*
* @param vb Pointer to struct virtio_base.
* @param vq Pointer to struct virtio_vq_info.
*
* @return None
*/
static inline void
vq_interrupt(struct virtio_base *vb, struct virtio_vq_info *vq)
{
if (pci_msix_enabled(vb->dev))
pci_generate_msix(vb->dev, vq->msix_idx);
else {
VIRTIO_BASE_LOCK(vb);
vb->isr |= VIRTIO_PCI_ISR_QUEUES;
pci_generate_msi(vb->dev, 0);
pci_lintr_assert(vb->dev);
VIRTIO_BASE_UNLOCK(vb);
}
}
/**
* @brief Deliver an config changed interrupt to guest.
*
* MSI-X or a generic MSI interrupt with config changed event.
*
* @param vb Pointer to struct virtio_base.
*
* @return None
*/
static inline void
virtio_config_changed(struct virtio_base *vb)
{
if (!(vb->status & VIRTIO_CONFIG_S_DRIVER_OK))
return;
vb->config_generation++;
if (pci_msix_enabled(vb->dev))
pci_generate_msix(vb->dev, vb->msix_cfg_idx);
else {
VIRTIO_BASE_LOCK(vb);
vb->isr |= VIRTIO_PCI_ISR_CONFIG;
pci_generate_msi(vb->dev, 0);
pci_lintr_assert(vb->dev);
VIRTIO_BASE_UNLOCK(vb);
}
}
struct iovec;
/**
* @brief Link a virtio_base to its constants, the virtio device,
* and the PCI emulation.
*
* @param base Pointer to struct virtio_base.
* @param vops Pointer to struct virtio_ops.
* @param pci_virtio_dev Pointer to instance of certain virtio device.
* @param dev Pointer to struct pci_vdev which emulates a PCI device.
* @param queues Pointer to struct virtio_vq_info, normally an array.
* @param backend_type can be VBSU, VBSK or VHOST
*
* @return None
*/
void virtio_linkup(struct virtio_base *base, struct virtio_ops *vops,
void *pci_virtio_dev, struct pci_vdev *dev,
struct virtio_vq_info *queues,
int backend_type);
/**
* @brief Get the virtio poll parameters
*
* @param optarg Pointer to parameters string.
*
* @return fail -1 success 0
*/
int acrn_parse_virtio_poll_interval(const char *optarg);
/**
* @brief Initialize MSI-X vector capabilities if we're to use MSI-X,
* or MSI capabilities if not.
*
* Wrapper function for virtio_intr_init() for cases we directly use
* BAR 1 for MSI-X capabilities.
*
* @param base Pointer to struct virtio_base.
* @param use_msix If using MSI-X.
*
* @return 0 on success and non-zero on fail.
*/
int virtio_interrupt_init(struct virtio_base *base, int use_msix);
/**
* @brief Initialize MSI-X vector capabilities if we're to use MSI-X,
* or MSI capabilities if not.
*
* We assume we want one MSI-X vector per queue, here, plus one
* for the config vec.
*
* @param base Pointer to struct virtio_base.
* @param barnum Which BAR[0..5] to use.
* @param use_msix If using MSI-X.
*
* @return 0 on success and non-zero on fail.
*/
int virtio_intr_init(struct virtio_base *base, int barnum, int use_msix);
/**
* @brief Reset device (device-wide).
*
* This erases all queues, i.e., all the queues become invalid.
* But we don't wipe out the internal pointers, by just clearing
* the VQ_ALLOC flag.
*
* It resets negotiated features to "none".
* If MSI-X is enabled, this also resets all the vectors to NO_VECTOR.
*
* @param base Pointer to struct virtio_base.
*
* @return None
*/
void virtio_reset_dev(struct virtio_base *base);
/**
* @brief Set I/O BAR (usually 0) to map PCI config registers.
*
* @param base Pointer to struct virtio_base.
* @param barnum Which BAR[0..5] to use.
*
* @return None
*/
void virtio_set_io_bar(struct virtio_base *base, int barnum);
/**
* @brief Walk through the chain of descriptors involved in a request
* and put them into a given iov[] array.
*
* @param vq Pointer to struct virtio_vq_info.
* @param pidx Pointer to available ring position.
* @param iov Pointer to iov[] array prepared by caller.
* @param n_iov Size of iov[] array.
* @param flags Pointer to a uint16_t array which will contain flag of
* each descriptor.
*
* @return number of descriptors.
*/
int vq_getchain(struct virtio_vq_info *vq, uint16_t *pidx,
struct iovec *iov, int n_iov, uint16_t *flags);
/**
* @brief Return the currently-first request chain back to the
* available ring.
*
* @param vq Pointer to struct virtio_vq_info.
*
* @return None
*/
void vq_retchain(struct virtio_vq_info *vq);
/**
* @brief Return specified request chain to the guest,
* setting its I/O length to the provided value.
*
* @param vq Pointer to struct virtio_vq_info.
* @param idx Pointer to available ring position, returned by vq_getchain().
* @param iolen Number of data bytes to be returned to frontend.
*
* @return None
*/
void vq_relchain(struct virtio_vq_info *vq, uint16_t idx, uint32_t iolen);
/**
* @brief Driver has finished processing "available" chains and calling
* vq_relchain on each one.
*
* If driver used all the available chains, used_all_avail need to be set to 1.
*
* @param vq Pointer to struct virtio_vq_info.
* @param used_all_avail Flag indicating if driver used all available chains.
*
* @return None
*/
void vq_endchains(struct virtio_vq_info *vq, int used_all_avail);
/**
* @brief Helper function for clearing used ring flags.
*
* Driver should always use this helper function to clear used ring flags.
* For virtio poll mode, in order to avoid trap, we should never really
* clear used ring flags.
*
* @param base Pointer to struct virtio_base.
* @param vq Pointer to struct virtio_vq_info.
*
* @return None
*/
void vq_clear_used_ring_flags(struct virtio_base *base, struct virtio_vq_info *vq);
/**
* @brief Handle PCI configuration space reads.
*
* Handle virtio standard register reads, and dispatch other reads to
* actual virtio device driver.
*
* @param ctx Pointer to struct vmctx representing VM context.
* @param vcpu VCPU ID.
* @param dev Pointer to struct pci_vdev which emulates a PCI device.
* @param baridx Which BAR[0..5] to use.
* @param offset Register offset in bytes within a BAR region.
* @param size Access range in bytes.
*
* @return register value.
*/
uint64_t virtio_pci_read(struct vmctx *ctx, int vcpu, struct pci_vdev *dev,
int baridx, uint64_t offset, int size);
/**
* @brief Handle PCI configuration space writes.
*
* Handle virtio standard register writes, and dispatch other writes to
* actual virtio device driver.
*
* @param ctx Pointer to struct vmctx representing VM context.
* @param vcpu VCPU ID.
* @param dev Pointer to struct pci_vdev which emulates a PCI device.
* @param baridx Which BAR[0..5] to use.
* @param offset Register offset in bytes within a BAR region.
* @param size Access range in bytes.
* @param value Data value to be written into register.
*
* @return None
*/
void virtio_pci_write(struct vmctx *ctx, int vcpu, struct pci_vdev *dev,
int baridx, uint64_t offset, int size, uint64_t value);
/**
* @brief Set modern BAR (usually 4) to map PCI config registers.
*
* Set modern MMIO BAR (usually 4) to map virtio 1.0 capabilities and optional
* set modern PIO BAR (usually 2) to map notify capability. This interface is
* only valid for modern virtio.
*
* @param base Pointer to struct virtio_base.
* @param use_notify_pio Whether use pio for notify capability.
*
* @return 0 on success and non-zero on fail.
*/
int virtio_set_modern_bar(struct virtio_base *base, bool use_notify_pio);
/**
* @}
*/
#endif /* _VIRTIO_H_ */
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