15325 bhyve upstream sync 2023 January

[illumos-gate.git] / usr / src / cmd / bhyve / virtio.h

/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * 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.
 *
 * $FreeBSD$
 */

#ifndef _BHYVE_VIRTIO_H_
#define _BHYVE_VIRTIO_H_

#include <pthread_np.h>
#include <machine/atomic.h>

#include <dev/virtio/virtio.h>
#ifdef __FreeBSD__
#include <dev/virtio/virtio_ring.h>
#include <dev/virtio/pci/virtio_pci_var.h>
#endif

/*
 * 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> (vu_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 --
 * VRING_AVAIL_F_NO_INTERRUPT and 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.)
 */
#define VRING_ALIGN     4096

/*
 * 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_PFN               12

/*
 * PCI vendor/device IDs
 */
#define VIRTIO_VENDOR           0x1AF4
#define VIRTIO_DEV_NET          0x1000
#define VIRTIO_DEV_BLOCK        0x1001
#define VIRTIO_DEV_CONSOLE      0x1003
#define VIRTIO_DEV_SCSI         0x1004
#define VIRTIO_DEV_RANDOM       0x1005
#define VIRTIO_DEV_9P           0x1009
#define VIRTIO_DEV_INPUT        0x1052

/*
 * PCI revision IDs
 */
#define VIRTIO_REV_INPUT        1

/*
 * PCI subvendor IDs
 */
#define VIRTIO_SUBVEN_INPUT     0x108E

/*
 * PCI subdevice IDs
 */
#define VIRTIO_SUBDEV_INPUT     0x1100

/* From section 2.3, "Virtqueue Configuration", of the virtio specification */
static inline int
vring_size_aligned(u_int qsz)
{
        return (roundup2(vring_size(qsz, VRING_ALIGN), VRING_ALIGN));
}

struct vmctx;
struct pci_devinst;
struct vqueue_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_softc should come
 * at the front of each "derived class", so that a pointer to the
 * virtio_softc is also a pointer to the more specific, derived-
 * from-virtio driver's softc.
 *
 * 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 vc_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    /* ??? */

struct virtio_softc {
        struct virtio_consts *vs_vc;    /* constants (see below) */
        int     vs_flags;               /* VIRTIO_* flags from above */
        pthread_mutex_t *vs_mtx;        /* POSIX mutex, if any */
        struct pci_devinst *vs_pi;      /* PCI device instance */
        uint32_t vs_negotiated_caps;    /* negotiated capabilities */
        struct vqueue_info *vs_queues;  /* one per vc_nvq */
        int     vs_curq;                /* current queue */
        uint8_t vs_status;              /* value from last status write */
        uint8_t vs_isr;                 /* ISR flags, if not MSI-X */
        uint16_t vs_msix_cfg_idx;       /* MSI-X vector for config event */
};

#define VS_LOCK(vs)                                                     \
do {                                                                    \
        if (vs->vs_mtx)                                                 \
                pthread_mutex_lock(vs->vs_mtx);                         \
} while (0)

#define VS_UNLOCK(vs)                                                   \
do {                                                                    \
        if (vs->vs_mtx)                                                 \
                pthread_mutex_unlock(vs->vs_mtx);                       \
} while (0)

struct virtio_consts {
        const char *vc_name;            /* name of driver (for diagnostics) */
        int     vc_nvq;                 /* number of virtual queues */
        size_t  vc_cfgsize;             /* size of dev-specific config regs */
        void    (*vc_reset)(void *);    /* called on virtual device reset */
        void    (*vc_qnotify)(void *, struct vqueue_info *);
                                        /* called on QNOTIFY if no VQ notify */
        int     (*vc_cfgread)(void *, int, int, uint32_t *);
                                        /* called to read config regs */
        int     (*vc_cfgwrite)(void *, int, int, uint32_t);
                                        /* called to write config regs */
        void    (*vc_apply_features)(void *, uint64_t);
                                /* called to apply negotiated features */
        uint64_t vc_hv_caps;            /* hypervisor-provided capabilities */
};

/*
 * Data structure allocated (statically) per virtual queue.
 *
 * Drivers may change vq_qsize after a reset.  When the guest OS
 * requests a device reset, the hypervisor first calls
 * vs->vs_vc->vc_reset(); then the data structure below is
 * reinitialized (for each virtqueue: vs->vs_vc->vc_nvq).
 *
 * The remaining fields should only be fussed-with by the generic
 * code.
 *
 * Note: the addresses of vq_desc, vq_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].
 */
#define VQ_ALLOC        0x01    /* set once we have a pfn */
#define VQ_BROKED       0x02    /* ??? */
struct vqueue_info {
        uint16_t vq_qsize;      /* size of this queue (a power of 2) */
        void    (*vq_notify)(void *, struct vqueue_info *);
                                /* called instead of vc_notify, if not NULL */

        struct virtio_softc *vq_vs;     /* backpointer to softc */
        uint16_t vq_num;        /* we're the num'th queue in the softc */

        uint16_t vq_flags;      /* flags (see above) */
        uint16_t vq_last_avail; /* a recent value of vq_avail->idx */
        uint16_t vq_next_used;  /* index of the next used slot to be filled */
        uint16_t vq_save_used;  /* saved vq_used->idx; see vq_endchains */
        uint16_t vq_msix_idx;   /* MSI-X index, or VIRTIO_MSI_NO_VECTOR */

        uint32_t vq_pfn;        /* PFN of virt queue (not shifted!) */

        struct vring_desc *vq_desc;     /* descriptor array */
        struct vring_avail *vq_avail;   /* the "avail" ring */
        struct vring_used *vq_used;     /* the "used" ring */

};
/* as noted above, these are sort of backwards, name-wise */
#define VQ_AVAIL_EVENT_IDX(vq) \
        (*(uint16_t *)&(vq)->vq_used->ring[(vq)->vq_qsize])
#define VQ_USED_EVENT_IDX(vq) \
        ((vq)->vq_avail->ring[(vq)->vq_qsize])

/*
 * Is this ring ready for I/O?
 */
static inline int
vq_ring_ready(struct vqueue_info *vq)
{

        return (vq->vq_flags & VQ_ALLOC);
}

/*
 * Are there "available" descriptors?  (This does not count
 * how many, just returns True if there are some.)
 */
static inline int
vq_has_descs(struct vqueue_info *vq)
{

        return (vq_ring_ready(vq) && vq->vq_last_avail !=
            vq->vq_avail->idx);
}

/*
 * Deliver an interrupt to the guest for a specific MSI-X queue or
 * event.
 */
static inline void
vi_interrupt(struct virtio_softc *vs, uint8_t isr, uint16_t msix_idx)
{

        if (pci_msix_enabled(vs->vs_pi))
                pci_generate_msix(vs->vs_pi, msix_idx);
        else {
#ifndef __FreeBSD__
                boolean_t unlock = B_FALSE;

                if (vs->vs_mtx && !pthread_mutex_isowned_np(vs->vs_mtx)) {
                        unlock = B_TRUE;
                        pthread_mutex_lock(vs->vs_mtx);
                }
#else
                VS_LOCK(vs);
#endif
                vs->vs_isr |= isr;
                pci_generate_msi(vs->vs_pi, 0);
                pci_lintr_assert(vs->vs_pi);
#ifndef __FreeBSD__
                if (unlock)
                        pthread_mutex_unlock(vs->vs_mtx);
#else
                VS_UNLOCK(vs);
#endif
        }
}

/*
 * Deliver an interrupt to the guest on the given virtual queue (if
 * possible, or a generic MSI interrupt if not using MSI-X).
 */
static inline void
vq_interrupt(struct virtio_softc *vs, struct vqueue_info *vq)
{

        vi_interrupt(vs, VIRTIO_PCI_ISR_INTR, vq->vq_msix_idx);
}

static inline void
vq_kick_enable(struct vqueue_info *vq)
{

        vq->vq_used->flags &= ~VRING_USED_F_NO_NOTIFY;
        /*
         * Full memory barrier to make sure the store to vq_used->flags
         * happens before the load from vq_avail->idx, which results from a
         * subsequent call to vq_has_descs().
         */
        atomic_thread_fence_seq_cst();
}

static inline void
vq_kick_disable(struct vqueue_info *vq)
{

        vq->vq_used->flags |= VRING_USED_F_NO_NOTIFY;
}

struct iovec;

/*
 * Request description returned by vq_getchain.
 *
 * Writable iovecs start at iov[req.readable].
 */
struct vi_req {
        int readable;           /* num of readable iovecs */
        int writable;           /* num of writable iovecs */
        unsigned int idx;       /* ring index */
};

void    vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc,
                        void *dev_softc, struct pci_devinst *pi,
                        struct vqueue_info *queues);
int     vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix);
void    vi_reset_dev(struct virtio_softc *);
void    vi_set_io_bar(struct virtio_softc *, int);

int     vq_getchain(struct vqueue_info *vq, struct iovec *iov, int niov,
            struct vi_req *reqp);
void    vq_retchains(struct vqueue_info *vq, uint16_t n_chains);
void    vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx,
                            uint32_t iolen);
void    vq_relchain_publish(struct vqueue_info *vq);
void    vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen);
void    vq_endchains(struct vqueue_info *vq, int used_all_avail);

uint64_t vi_pci_read(struct vmctx *ctx, struct pci_devinst *pi,
                     int baridx, uint64_t offset, int size);
void    vi_pci_write(struct vmctx *ctx, struct pci_devinst *pi,
                     int baridx, uint64_t offset, int size, uint64_t value);
#endif  /* _BHYVE_VIRTIO_H_ */