Super User's BSD Cross Reference: /FreeBSD/usr.sbin/bhyve/virtio.c

 /*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2013 Chris Torek <torek @ torek net>
 * All rights reserved.
 * Copyright (c) 2019 Joyent, Inc.
 *
 * 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.
 */

#include <sys/cdefs.h>
 __FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/uio.h>

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

#include <stdio.h>
#include <stdint.h>
#include <pthread.h>
#include <pthread_np.h>

#include "bhyverun.h"
#include "debug.h"
#include "pci_emul.h"
#include "virtio.h"

 /*
 * Functions for dealing with generalized "virtual devices" as
 * defined by <https://www.google.com/#output=search&q=virtio+spec>
 */

 /*
 * In case we decide to relax the "virtio softc comes at the
 * front of virtio-based device softc" constraint, let's use
 * this to convert.
 */
#define DEV_SOFTC(vs) ((void *)(vs))

 /*
 * Link a virtio_softc to its constants, the device softc, and
 * the PCI emulation.
 */
 void
 vi_softc_linkup(struct virtio_softc *vs, struct virtio_consts *vc,
 void *dev_softc, struct pci_devinst *pi,
 struct vqueue_info *queues)
{
 int i;

 /* vs and dev_softc addresses must match */
 assert((void *)vs == dev_softc);
 vs->vs_vc = vc;
 vs->vs_pi = pi;
 pi->pi_arg = vs;

 vs->vs_queues = queues;
 for (i = 0; i < vc->vc_nvq; i++) {
 queues[i].vq_vs = vs;
 queues[i].vq_num = i;
 }
}

 /*
 * Reset device (device-wide). This erases all queues, i.e.,
 * all the queues become invalid (though we don't wipe out the
 * internal pointers, we just clear the VQ_ALLOC flag).
 *
 * It resets negotiated features to "none".
 *
 * If MSI-X is enabled, this also resets all the vectors to NO_VECTOR.
 */
 void
 vi_reset_dev(struct virtio_softc *vs)
{
 struct vqueue_info *vq;
 int i, nvq;

 if (vs->vs_mtx)
 assert(pthread_mutex_isowned_np(vs->vs_mtx));

 nvq = vs->vs_vc->vc_nvq;
 for (vq = vs->vs_queues, i = 0; i < nvq; vq++, i++) {
 vq->vq_flags = 0;
 vq->vq_last_avail = 0;
 vq->vq_next_used = 0;
 vq->vq_save_used = 0;
 vq->vq_pfn = 0;
 vq->vq_msix_idx = VIRTIO_MSI_NO_VECTOR;
 }
 vs->vs_negotiated_caps = 0;
 vs->vs_curq = 0;
 /* vs->vs_status = 0; -- redundant */
 if (vs->vs_isr)
 pci_lintr_deassert(vs->vs_pi);
 vs->vs_isr = 0;
 vs->vs_msix_cfg_idx = VIRTIO_MSI_NO_VECTOR;
}

 /*
 * Set I/O BAR (usually 0) to map PCI config registers.
 */
 void
 vi_set_io_bar(struct virtio_softc *vs, int barnum)
{
 size_t size;

 /*
 * ??? should we use CFG0 if MSI-X is disabled?
 * Existing code did not...
 */
 size = VTCFG_R_CFG1 + vs->vs_vc->vc_cfgsize;
 pci_emul_alloc_bar(vs->vs_pi, barnum, PCIBAR_IO, size);
}

 /*
 * 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.
 */
 int
 vi_intr_init(struct virtio_softc *vs, int barnum, int use_msix)
{
 int nvec;

 if (use_msix) {
 vs->vs_flags |= VIRTIO_USE_MSIX;
 VS_LOCK(vs);
 vi_reset_dev(vs); /* set all vectors to NO_VECTOR */
 VS_UNLOCK(vs);
 nvec = vs->vs_vc->vc_nvq + 1;
 if (pci_emul_add_msixcap(vs->vs_pi, nvec, barnum))
 return (1);
 } else
 vs->vs_flags &= ~VIRTIO_USE_MSIX;

 /* Only 1 MSI vector for bhyve */
 pci_emul_add_msicap(vs->vs_pi, 1);

 /* Legacy interrupts are mandatory for virtio devices */
 pci_lintr_request(vs->vs_pi);

 return (0);
}

 /*
 * Initialize the currently-selected virtio queue (vs->vs_curq).
 * The guest just gave us a page frame number, from which we can
 * calculate the addresses of the queue.
 */
 void
 vi_vq_init(struct virtio_softc *vs, uint32_t pfn)
{
 struct vqueue_info *vq;
 uint64_t phys;
 size_t size;
 char *base;

 vq = &vs->vs_queues[vs->vs_curq];
 vq->vq_pfn = pfn;
 phys = (uint64_t)pfn << VRING_PFN;
 size = vring_size(vq->vq_qsize);
 base = paddr_guest2host(vs->vs_pi->pi_vmctx, phys, size);

 /* First page(s) are descriptors... */
 vq->vq_desc = (struct virtio_desc *)base;
 base += vq->vq_qsize * sizeof(struct virtio_desc);

 /* ... immediately followed by "avail" ring (entirely uint16_t's) */
 vq->vq_avail = (struct vring_avail *)base;
 base += (2 + vq->vq_qsize + 1) * sizeof(uint16_t);

 /* Then it's rounded up to the next page... */
 base = (char *)roundup2((uintptr_t)base, VRING_ALIGN);

 /* ... and the last page(s) are the used ring. */
 vq->vq_used = (struct vring_used *)base;

 /* Mark queue as allocated, and start at 0 when we use it. */
 vq->vq_flags = VQ_ALLOC;
 vq->vq_last_avail = 0;
 vq->vq_next_used = 0;
 vq->vq_save_used = 0;
}

 /*
 * Helper inline for vq_getchain(): record the i'th "real"
 * descriptor.
 */
 static inline void
 _vq_record(int i, volatile struct virtio_desc *vd, struct vmctx *ctx,
 struct iovec *iov, int n_iov, uint16_t *flags) {

 if (i >= n_iov)
 return;
 iov[i].iov_base = paddr_guest2host(ctx, vd->vd_addr, vd->vd_len);
 iov[i].iov_len = vd->vd_len;
 if (flags != NULL)
 flags[i] = vd->vd_flags;
}
#define VQ_MAX_DESCRIPTORS 512 /* see below */

 /*
 * Examine the chain of descriptors starting at the "next one" to
 * make sure that they describe a sensible request. If so, return
 * the number of "real" descriptors that would be needed/used in
 * acting on this request. This may be smaller than the number of
 * available descriptors, e.g., if there are two available but
 * they are two separate requests, this just returns 1. Or, it
 * may be larger: if there are indirect descriptors involved,
 * there may only be one descriptor available but it may be an
 * indirect pointing to eight more. We return 8 in this case,
 * i.e., we do not count the indirect descriptors, only the "real"
 * ones.
 *
 * Basically, this vets the vd_flags and vd_next field of each
 * descriptor and tells you how many are involved. Since some may
 * be indirect, this also needs the vmctx (in the pci_devinst
 * at vs->vs_pi) so that it can find indirect descriptors.
 *
 * As we process each descriptor, we copy and adjust it (guest to
 * host address wise, also using the vmtctx) into the given iov[]
 * array (of the given size). If the array overflows, we stop
 * placing values into the array but keep processing descriptors,
 * up to VQ_MAX_DESCRIPTORS, before giving up and returning -1.
 * So you, the caller, must not assume that iov[] is as big as the
 * return value (you can process the same thing twice to allocate
 * a larger iov array if needed, or supply a zero length to find
 * out how much space is needed).
 *
 * If you want to verify the WRITE flag on each descriptor, pass a
 * non-NULL "flags" pointer to an array of "uint16_t" of the same size
 * as n_iov and we'll copy each vd_flags field after unwinding any
 * indirects.
 *
 * If some descriptor(s) are invalid, this prints a diagnostic message
 * and returns -1. If no descriptors are ready now it simply returns 0.
 *
 * You are assumed to have done a vq_ring_ready() if needed (note
 * that vq_has_descs() does one).
 */
 int
 vq_getchain(struct vqueue_info *vq, uint16_t *pidx,
 struct iovec *iov, int n_iov, uint16_t *flags)
{
 int i;
 u_int ndesc, n_indir;
 u_int idx, next;
 volatile struct virtio_desc *vdir, *vindir, *vp;
 struct vmctx *ctx;
 struct virtio_softc *vs;
 const char *name;

 vs = vq->vq_vs;
 name = vs->vs_vc->vc_name;

 /*
 * Note: it's the responsibility of the guest not to
 * update vq->vq_avail->va_idx until all of the descriptors
 * the guest has written are valid (including all their
 * vd_next fields and vd_flags).
 *
 * Compute (va_idx - last_avail) in integers mod 2**16. This is
 * the number of descriptors the device has made available
 * since the last time we updated vq->vq_last_avail.
 *
 * We just need to do the subtraction as an unsigned int,
 * then trim off excess bits.
 */
 idx = vq->vq_last_avail;
 ndesc = (uint16_t)((u_int)vq->vq_avail->va_idx - idx);
 if (ndesc == 0)
 return (0);
 if (ndesc > vq->vq_qsize) {
 /* XXX need better way to diagnose issues */
 EPRINTLN(
 "%s: ndesc (%u) out of range, driver confused?",
 name, (u_int)ndesc);
 return (-1);
 }

 /*
 * Now count/parse "involved" descriptors starting from
 * the head of the chain.
 *
 * To prevent loops, we could be more complicated and
 * check whether we're re-visiting a previously visited
 * index, but we just abort if the count gets excessive.
 */
 ctx = vs->vs_pi->pi_vmctx;
 *pidx = next = vq->vq_avail->va_ring[idx & (vq->vq_qsize - 1)];
 vq->vq_last_avail++;
 for (i = 0; i < VQ_MAX_DESCRIPTORS; next = vdir->vd_next) {
 if (next >= vq->vq_qsize) {
 EPRINTLN(
 "%s: descriptor index %u out of range, "
 "driver confused?",
 name, next);
 return (-1);
 }
 vdir = &vq->vq_desc[next];
 if ((vdir->vd_flags & VRING_DESC_F_INDIRECT) == 0) {
 _vq_record(i, vdir, ctx, iov, n_iov, flags);
 i++;
 } else if ((vs->vs_vc->vc_hv_caps &
 VIRTIO_RING_F_INDIRECT_DESC) == 0) {
 EPRINTLN(
 "%s: descriptor has forbidden INDIRECT flag, "
 "driver confused?",
 name);
 return (-1);
 } else {
 n_indir = vdir->vd_len / 16;
 if ((vdir->vd_len & 0xf) || n_indir == 0) {
 EPRINTLN(
 "%s: invalid indir len 0x%x, "
 "driver confused?",
 name, (u_int)vdir->vd_len);
 return (-1);
 }
 vindir = paddr_guest2host(ctx,
 vdir->vd_addr, vdir->vd_len);
 /*
 * Indirects start at the 0th, then follow
 * their own embedded "next"s until those run
 * out. Each one's indirect flag must be off
 * (we don't really have to check, could just
 * ignore errors...).
 */
 next = 0;
 for (;;) {
 vp = &vindir[next];
 if (vp->vd_flags & VRING_DESC_F_INDIRECT) {
 EPRINTLN(
 "%s: indirect desc has INDIR flag,"
 " driver confused?",
 name);
 return (-1);
 }
 _vq_record(i, vp, ctx, iov, n_iov, flags);
 if (++i > VQ_MAX_DESCRIPTORS)
 goto loopy;
 if ((vp->vd_flags & VRING_DESC_F_NEXT) == 0)
 break;
 next = vp->vd_next;
 if (next >= n_indir) {
 EPRINTLN(
 "%s: invalid next %u > %u, "
 "driver confused?",
 name, (u_int)next, n_indir);
 return (-1);
 }
 }
 }
 if ((vdir->vd_flags & VRING_DESC_F_NEXT) == 0)
 return (i);
 }
 loopy:
 EPRINTLN(
 "%s: descriptor loop? count > %d - driver confused?",
 name, i);
 return (-1);
}

 /*
 * Return the first n_chain request chains back to the available queue.
 *
 * (These chains are the ones you handled when you called vq_getchain()
 * and used its positive return value.)
 */
 void
 vq_retchains(struct vqueue_info *vq, uint16_t n_chains)
{

 vq->vq_last_avail -= n_chains;
}

 void
 vq_relchain_prepare(struct vqueue_info *vq, uint16_t idx, uint32_t iolen)
{
 volatile struct vring_used *vuh;
 volatile struct virtio_used *vue;
 uint16_t mask;

 /*
 * Notes:
 * - mask is N-1 where N is a power of 2 so computes x % N
 * - vuh points to the "used" data shared with guest
 * - vue points to the "used" ring entry we want to update
 *
 * (I apologize for the two fields named vu_idx; the
 * virtio spec calls the one that vue points to, "id"...)
 */
 mask = vq->vq_qsize - 1;
 vuh = vq->vq_used;

 vue = &vuh->vu_ring[vq->vq_next_used++ & mask];
 vue->vu_idx = idx;
 vue->vu_tlen = iolen;
}

 void
 vq_relchain_publish(struct vqueue_info *vq)
{
 /*
 * Ensure the used descriptor is visible before updating the index.
 * This is necessary on ISAs with memory ordering less strict than x86
 * (and even on x86 to act as a compiler barrier).
 */
 atomic_thread_fence_rel();
 vq->vq_used->vu_idx = vq->vq_next_used;
}

 /*
 * Return specified request chain to the guest, setting its I/O length
 * to the provided value.
 *
 * (This chain is the one you handled when you called vq_getchain()
 * and used its positive return value.)
 */
 void
 vq_relchain(struct vqueue_info *vq, uint16_t idx, uint32_t iolen)
{
 vq_relchain_prepare(vq, idx, iolen);
 vq_relchain_publish(vq);
}

 /*
 * Driver has finished processing "available" chains and calling
 * vq_relchain on each one. If driver used all the available
 * chains, used_all should be set.
 *
 * If the "used" index moved we may need to inform the guest, i.e.,
 * deliver an interrupt. Even if the used index did NOT move we
 * may need to deliver an interrupt, if the avail ring is empty and
 * we are supposed to interrupt on empty.
 *
 * Note that used_all_avail is provided by the caller because it's
 * a snapshot of the ring state when he decided to finish interrupt
 * processing -- it's possible that descriptors became available after
 * that point. (It's also typically a constant 1/True as well.)
 */
 void
 vq_endchains(struct vqueue_info *vq, int used_all_avail)
{
 struct virtio_softc *vs;
 uint16_t event_idx, new_idx, old_idx;
 int intr;

 /*
 * Interrupt generation: if we're using EVENT_IDX,
 * interrupt if we've crossed the event threshold.
 * Otherwise interrupt is generated if we added "used" entries,
 * but suppressed by VRING_AVAIL_F_NO_INTERRUPT.
 *
 * In any case, though, if NOTIFY_ON_EMPTY is set and the
 * entire avail was processed, we need to interrupt always.
 */
 vs = vq->vq_vs;
 old_idx = vq->vq_save_used;
 vq->vq_save_used = new_idx = vq->vq_used->vu_idx;

 /*
 * Use full memory barrier between vu_idx store from preceding
 * vq_relchain() call and the loads from VQ_USED_EVENT_IDX() or
 * va_flags below.
 */
 atomic_thread_fence_seq_cst();
 if (used_all_avail &&
 (vs->vs_negotiated_caps & VIRTIO_F_NOTIFY_ON_EMPTY))
 intr = 1;
 else if (vs->vs_negotiated_caps & VIRTIO_RING_F_EVENT_IDX) {
 event_idx = VQ_USED_EVENT_IDX(vq);
 /*
 * This calculation is per docs and the kernel
 * (see src/sys/dev/virtio/virtio_ring.h).
 */
 intr = (uint16_t)(new_idx - event_idx - 1) <
 (uint16_t)(new_idx - old_idx);
 } else {
 intr = new_idx != old_idx &&
 !(vq->vq_avail->va_flags & VRING_AVAIL_F_NO_INTERRUPT);
 }
 if (intr)
 vq_interrupt(vs, vq);
}

 /* Note: these are in sorted order to make for a fast search */
 static struct config_reg {
 uint16_t cr_offset; /* register offset */
 uint8_t cr_size; /* size (bytes) */
 uint8_t cr_ro; /* true => reg is read only */
 const char *cr_name; /* name of reg */
} config_regs[] = {
 { VTCFG_R_HOSTCAP, 4, 1, "HOSTCAP" },
 { VTCFG_R_GUESTCAP, 4, 0, "GUESTCAP" },
 { VTCFG_R_PFN, 4, 0, "PFN" },
 { VTCFG_R_QNUM, 2, 1, "QNUM" },
 { VTCFG_R_QSEL, 2, 0, "QSEL" },
 { VTCFG_R_QNOTIFY, 2, 0, "QNOTIFY" },
 { VTCFG_R_STATUS, 1, 0, "STATUS" },
 { VTCFG_R_ISR, 1, 0, "ISR" },
 { VTCFG_R_CFGVEC, 2, 0, "CFGVEC" },
 { VTCFG_R_QVEC, 2, 0, "QVEC" },
};

 static inline struct config_reg *
 vi_find_cr(int offset) {
 u_int hi, lo, mid;
 struct config_reg *cr;

 lo = 0;
 hi = sizeof(config_regs) / sizeof(*config_regs) - 1;
 while (hi >= lo) {
 mid = (hi + lo) >> 1;
 cr = &config_regs[mid];
 if (cr->cr_offset == offset)
 return (cr);
 if (cr->cr_offset < offset)
 lo = mid + 1;
 else
 hi = mid - 1;
 }
 return (NULL);
}

 /*
 * Handle pci config space reads.
 * If it's to the MSI-X info, do that.
 * If it's part of the virtio standard stuff, do that.
 * Otherwise dispatch to the actual driver.
 */
 uint64_t
 vi_pci_read(struct vmctx *ctx, int vcpu, struct pci_devinst *pi,
 int baridx, uint64_t offset, int size)
{
 struct virtio_softc *vs = pi->pi_arg;
 struct virtio_consts *vc;
 struct config_reg *cr;
 uint64_t virtio_config_size, max;
 const char *name;
 uint32_t newoff;
 uint32_t value;
 int error;

 if (vs->vs_flags & VIRTIO_USE_MSIX) {
 if (baridx == pci_msix_table_bar(pi) ||
 baridx == pci_msix_pba_bar(pi)) {
 return (pci_emul_msix_tread(pi, offset, size));
 }
 }

 /* XXX probably should do something better than just assert() */
 assert(baridx == 0);

 if (vs->vs_mtx)
 pthread_mutex_lock(vs->vs_mtx);

 vc = vs->vs_vc;
 name = vc->vc_name;
 value = size == 1 ? 0xff : size == 2 ? 0xffff : 0xffffffff;

 if (size != 1 && size != 2 && size != 4)
 goto bad;

 if (pci_msix_enabled(pi))
 virtio_config_size = VTCFG_R_CFG1;
 else
 virtio_config_size = VTCFG_R_CFG0;

 if (offset >= virtio_config_size) {
 /*
 * Subtract off the standard size (including MSI-X
 * registers if enabled) and dispatch to underlying driver.
 * If that fails, fall into general code.
 */
 newoff = offset - virtio_config_size;
 max = vc->vc_cfgsize ? vc->vc_cfgsize : 0x100000000;
 if (newoff + size > max)
 goto bad;
 error = (*vc->vc_cfgread)(DEV_SOFTC(vs), newoff, size, &value);
 if (!error)
 goto done;
 }

 bad:
 cr = vi_find_cr(offset);
 if (cr == NULL || cr->cr_size != size) {
 if (cr != NULL) {
 /* offset must be OK, so size must be bad */
 EPRINTLN(
 "%s: read from %s: bad size %d",
 name, cr->cr_name, size);
 } else {
 EPRINTLN(
 "%s: read from bad offset/size %jd/%d",
 name, (uintmax_t)offset, size);
 }
 goto done;
 }

 switch (offset) {
 case VTCFG_R_HOSTCAP:
 value = vc->vc_hv_caps;
 break;
 case VTCFG_R_GUESTCAP:
 value = vs->vs_negotiated_caps;
 break;
 case VTCFG_R_PFN:
 if (vs->vs_curq < vc->vc_nvq)
 value = vs->vs_queues[vs->vs_curq].vq_pfn;
 break;
 case VTCFG_R_QNUM:
 value = vs->vs_curq < vc->vc_nvq ?
 vs->vs_queues[vs->vs_curq].vq_qsize : 0;
 break;
 case VTCFG_R_QSEL:
 value = vs->vs_curq;
 break;
 case VTCFG_R_QNOTIFY:
 value = 0; /* XXX */
 break;
 case VTCFG_R_STATUS:
 value = vs->vs_status;
 break;
 case VTCFG_R_ISR:
 value = vs->vs_isr;
 vs->vs_isr = 0; /* a read clears this flag */
 if (value)
 pci_lintr_deassert(pi);
 break;
 case VTCFG_R_CFGVEC:
 value = vs->vs_msix_cfg_idx;
 break;
 case VTCFG_R_QVEC:
 value = vs->vs_curq < vc->vc_nvq ?
 vs->vs_queues[vs->vs_curq].vq_msix_idx :
 VIRTIO_MSI_NO_VECTOR;
 break;
 }
 done:
 if (vs->vs_mtx)
 pthread_mutex_unlock(vs->vs_mtx);
 return (value);
}

 /*
 * Handle pci config space writes.
 * If it's to the MSI-X info, do that.
 * If it's part of the virtio standard stuff, do that.
 * Otherwise dispatch to the actual driver.
 */
 void
 vi_pci_write(struct vmctx *ctx, int vcpu, struct pci_devinst *pi,
 int baridx, uint64_t offset, int size, uint64_t value)
{
 struct virtio_softc *vs = pi->pi_arg;
 struct vqueue_info *vq;
 struct virtio_consts *vc;
 struct config_reg *cr;
 uint64_t virtio_config_size, max;
 const char *name;
 uint32_t newoff;
 int error;

 if (vs->vs_flags & VIRTIO_USE_MSIX) {
 if (baridx == pci_msix_table_bar(pi) ||
 baridx == pci_msix_pba_bar(pi)) {
 pci_emul_msix_twrite(pi, offset, size, value);
 return;
 }
 }

 /* XXX probably should do something better than just assert() */
 assert(baridx == 0);

 if (vs->vs_mtx)
 pthread_mutex_lock(vs->vs_mtx);

 vc = vs->vs_vc;
 name = vc->vc_name;

 if (size != 1 && size != 2 && size != 4)
 goto bad;

 if (pci_msix_enabled(pi))
 virtio_config_size = VTCFG_R_CFG1;
 else
 virtio_config_size = VTCFG_R_CFG0;

 if (offset >= virtio_config_size) {
 /*
 * Subtract off the standard size (including MSI-X
 * registers if enabled) and dispatch to underlying driver.
 */
 newoff = offset - virtio_config_size;
 max = vc->vc_cfgsize ? vc->vc_cfgsize : 0x100000000;
 if (newoff + size > max)
 goto bad;
 error = (*vc->vc_cfgwrite)(DEV_SOFTC(vs), newoff, size, value);
 if (!error)
 goto done;
 }

 bad:
 cr = vi_find_cr(offset);
 if (cr == NULL || cr->cr_size != size || cr->cr_ro) {
 if (cr != NULL) {
 /* offset must be OK, wrong size and/or reg is R/O */
 if (cr->cr_size != size)
 EPRINTLN(
 "%s: write to %s: bad size %d",
 name, cr->cr_name, size);
 if (cr->cr_ro)
 EPRINTLN(
 "%s: write to read-only reg %s",
 name, cr->cr_name);
 } else {
 EPRINTLN(
 "%s: write to bad offset/size %jd/%d",
 name, (uintmax_t)offset, size);
 }
 goto done;
 }

 switch (offset) {
 case VTCFG_R_GUESTCAP:
 vs->vs_negotiated_caps = value & vc->vc_hv_caps;
 if (vc->vc_apply_features)
 (*vc->vc_apply_features)(DEV_SOFTC(vs),
 vs->vs_negotiated_caps);
 break;
 case VTCFG_R_PFN:
 if (vs->vs_curq >= vc->vc_nvq)
 goto bad_qindex;
 vi_vq_init(vs, value);
 break;
 case VTCFG_R_QSEL:
 /*
 * Note that the guest is allowed to select an
 * invalid queue; we just need to return a QNUM
 * of 0 while the bad queue is selected.
 */
 vs->vs_curq = value;
 break;
 case VTCFG_R_QNOTIFY:
 if (value >= vc->vc_nvq) {
 EPRINTLN("%s: queue %d notify out of range",
 name, (int)value);
 goto done;
 }
 vq = &vs->vs_queues[value];
 if (vq->vq_notify)
 (*vq->vq_notify)(DEV_SOFTC(vs), vq);
 else if (vc->vc_qnotify)
 (*vc->vc_qnotify)(DEV_SOFTC(vs), vq);
 else
 EPRINTLN(
 "%s: qnotify queue %d: missing vq/vc notify",
 name, (int)value);
 break;
 case VTCFG_R_STATUS:
 vs->vs_status = value;
 if (value == 0)
 (*vc->vc_reset)(DEV_SOFTC(vs));
 break;
 case VTCFG_R_CFGVEC:
 vs->vs_msix_cfg_idx = value;
 break;
 case VTCFG_R_QVEC:
 if (vs->vs_curq >= vc->vc_nvq)
 goto bad_qindex;
 vq = &vs->vs_queues[vs->vs_curq];
 vq->vq_msix_idx = value;
 break;
 }
 goto done;

 bad_qindex:
 EPRINTLN(
 "%s: write config reg %s: curq %d >= max %d",
 name, cr->cr_name, vs->vs_curq, vc->vc_nvq);
 done:
 if (vs->vs_mtx)
 pthread_mutex_unlock(vs->vs_mtx);
}

#ifdef BHYVE_SNAPSHOT
 int
 vi_pci_pause(struct vmctx *ctx, struct pci_devinst *pi)
{
 struct virtio_softc *vs;
 struct virtio_consts *vc;

 vs = pi->pi_arg;
 vc = vs->vs_vc;

 vc = vs->vs_vc;
 assert(vc->vc_pause != NULL);
 (*vc->vc_pause)(DEV_SOFTC(vs));

 return (0);
}

 int
 vi_pci_resume(struct vmctx *ctx, struct pci_devinst *pi)
{
 struct virtio_softc *vs;
 struct virtio_consts *vc;

 vs = pi->pi_arg;
 vc = vs->vs_vc;

 vc = vs->vs_vc;
 assert(vc->vc_resume != NULL);
 (*vc->vc_resume)(DEV_SOFTC(vs));

 return (0);
}

 static int
 vi_pci_snapshot_softc(struct virtio_softc *vs, struct vm_snapshot_meta *meta)
{
 int ret;

 SNAPSHOT_VAR_OR_LEAVE(vs->vs_flags, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vs->vs_negotiated_caps, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vs->vs_curq, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vs->vs_status, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vs->vs_isr, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vs->vs_msix_cfg_idx, meta, ret, done);

 done:
 return (ret);
}

 static int
 vi_pci_snapshot_consts(struct virtio_consts *vc, struct vm_snapshot_meta *meta)
{
 int ret;

 SNAPSHOT_VAR_CMP_OR_LEAVE(vc->vc_nvq, meta, ret, done);
 SNAPSHOT_VAR_CMP_OR_LEAVE(vc->vc_cfgsize, meta, ret, done);
 SNAPSHOT_VAR_CMP_OR_LEAVE(vc->vc_hv_caps, meta, ret, done);

 done:
 return (ret);
}

 static int
 vi_pci_snapshot_queues(struct virtio_softc *vs, struct vm_snapshot_meta *meta)
{
 int i;
 int ret;
 struct virtio_consts *vc;
 struct vqueue_info *vq;
 uint64_t addr_size;

 vc = vs->vs_vc;

 /* Save virtio queue info */
 for (i = 0; i < vc->vc_nvq; i++) {
 vq = &vs->vs_queues[i];

 SNAPSHOT_VAR_CMP_OR_LEAVE(vq->vq_qsize, meta, ret, done);
 SNAPSHOT_VAR_CMP_OR_LEAVE(vq->vq_num, meta, ret, done);

 SNAPSHOT_VAR_OR_LEAVE(vq->vq_flags, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vq->vq_last_avail, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vq->vq_next_used, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vq->vq_save_used, meta, ret, done);
 SNAPSHOT_VAR_OR_LEAVE(vq->vq_msix_idx, meta, ret, done);

 SNAPSHOT_VAR_OR_LEAVE(vq->vq_pfn, meta, ret, done);

 addr_size = vq->vq_qsize * sizeof(struct virtio_desc);
 SNAPSHOT_GUEST2HOST_ADDR_OR_LEAVE(vq->vq_desc, addr_size,
 false, meta, ret, done);

 addr_size = (2 + vq->vq_qsize + 1) * sizeof(uint16_t);
 SNAPSHOT_GUEST2HOST_ADDR_OR_LEAVE(vq->vq_avail, addr_size,
 false, meta, ret, done);

 addr_size = (2 + 2 * vq->vq_qsize + 1) * sizeof(uint16_t);
 SNAPSHOT_GUEST2HOST_ADDR_OR_LEAVE(vq->vq_used, addr_size,
 false, meta, ret, done);

 SNAPSHOT_BUF_OR_LEAVE(vq->vq_desc, vring_size(vq->vq_qsize),
 meta, ret, done);
 }

 done:
 return (ret);
}

 int
 vi_pci_snapshot(struct vm_snapshot_meta *meta)
{
 int ret;
 struct pci_devinst *pi;
 struct virtio_softc *vs;
 struct virtio_consts *vc;

 pi = meta->dev_data;
 vs = pi->pi_arg;
 vc = vs->vs_vc;

 /* Save virtio softc */
 ret = vi_pci_snapshot_softc(vs, meta);
 if (ret != 0)
 goto done;

 /* Save virtio consts */
 ret = vi_pci_snapshot_consts(vc, meta);
 if (ret != 0)
 goto done;

 /* Save virtio queue info */
 ret = vi_pci_snapshot_queues(vs, meta);
 if (ret != 0)
 goto done;

 /* Save device softc, if needed */
 if (vc->vc_snapshot != NULL) {
 ret = (*vc->vc_snapshot)(DEV_SOFTC(vs), meta);
 if (ret != 0)
 goto done;
 }

 done:
 return (ret);
}
#endif
 

Indexes created Fri Nov 14 03:53:34 PST 2025