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freebsd-skq/usr.sbin/bhyve/virtio.h
Peter Grehan ba41c3c13f Major rework of the virtio code. Split out common parts, and modify 
the net/block devices accordingly.

Submitted by:	Chris Torek   torek at torek dot net
Reviewed by:	grehan
2013-07-17 23:37:33 +00:00

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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.
*
* $FreeBSD$
*/
#ifndef _VIRTIO_H_
#define _VIRTIO_H_
/*
* These are derived from several virtio specifications.
*
* Some useful links:
* https://github.com/rustyrussel/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
#define VRING_DESC_F_NEXT (1 << 0)
#define VRING_DESC_F_WRITE (1 << 1)
#define VRING_DESC_F_INDIRECT (1 << 2)
struct virtio_desc { /* AKA vring_desc */
uint64_t vd_addr; /* guest physical address */
uint32_t vd_len; /* length of scatter/gather seg */
uint16_t vd_flags; /* VRING_F_DESC_* */
uint16_t vd_next; /* next desc if F_NEXT */
} __packed;
struct virtio_used { /* AKA vring_used_elem */
uint32_t vu_idx; /* head of used descriptor chain */
uint32_t vu_tlen; /* length written-to */
} __packed;
#define VRING_AVAIL_F_NO_INTERRUPT 1
struct vring_avail {
uint16_t va_flags; /* VRING_AVAIL_F_* */
uint16_t va_idx; /* counts to 65535, then cycles */
uint16_t va_ring[]; /* size N, reported in QNUM value */
/* uint16_t va_used_event; -- after N ring entries */
} __packed;
#define VRING_USED_F_NO_NOTIFY 1
struct vring_used {
uint16_t vu_flags; /* VRING_USED_F_* */
uint16_t vu_idx; /* counts to 65535, then cycles */
struct virtio_used vu_ring[]; /* size N */
/* uint16_t vu_avail_event; -- after N ring entries */
} __packed;
/*
* 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
/*
* Virtio device types
*
* XXX Should really be merged with <dev/virtio/virtio.h> defines
*/
#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
/* experimental IDs start at 65535 and work down */
/*
* PCI vendor/device IDs
*/
#define VIRTIO_VENDOR 0x1AF4
#define VIRTIO_DEV_NET 0x1000
#define VIRTIO_DEV_BLOCK 0x1001
/*
* PCI config space constants.
*
* If MSI-X is enabled, the ISR register is generally not used,
* and the configuration vector and queue vector appear at offsets
* 20 and 22 with the remaining configuration registers at 24.
* If MSI-X is not enabled, those two registers disappear and
* the remaining configuration registers start at offset 20.
*/
#define VTCFG_R_HOSTCAP 0
#define VTCFG_R_GUESTCAP 4
#define VTCFG_R_PFN 8
#define VTCFG_R_QNUM 12
#define VTCFG_R_QSEL 14
#define VTCFG_R_QNOTIFY 16
#define VTCFG_R_STATUS 18
#define VTCFG_R_ISR 19
#define VTCFG_R_CFGVEC 20
#define VTCFG_R_QVEC 22
#define VTCFG_R_CFG0 20 /* No MSI-X */
#define VTCFG_R_CFG1 24 /* With MSI-X */
#define VTCFG_R_MSIX 20
/*
* Bits in VTCFG_R_STATUS. Guests need not actually set any of these,
* but a guest writing 0 to this register means "please reset".
*/
#define VTCFG_STATUS_ACK 0x01 /* guest OS has acknowledged dev */
#define VTCFG_STATUS_DRIVER 0x02 /* guest OS driver is loaded */
#define VTCFG_STATUS_DRIVER_OK 0x04 /* guest OS driver ready */
#define VTCFG_STATUS_FAILED 0x80 /* guest has given up on this dev */
/*
* Bits in VTCFG_R_ISR. These apply only if not using MSI-X.
*
* (We don't [yet?] ever use CONF_CHANGED.)
*/
#define VTCFG_ISR_QUEUES 0x01 /* re-scan queues */
#define VTCFG_ISR_CONF_CHANGED 0x80 /* configuration changed */
#define VIRTIO_MSI_NO_VECTOR 0xFFFF
/*
* Feature flags.
* Note: bits 0 through 23 are reserved to each device type.
*/
#define VIRTIO_F_NOTIFY_ON_EMPTY (1 << 24)
#define VIRTIO_RING_F_INDIRECT_DESC (1 << 28)
#define VIRTIO_RING_F_EVENT_IDX (1 << 29)
/* From section 2.3, "Virtqueue Configuration", of the virtio specification */
static inline size_t
vring_size(u_int qsz)
{
size_t size;
/* constant 3 below = va_flags, va_idx, va_used_event */
size = sizeof(struct virtio_desc) * qsz + sizeof(uint16_t) * (3 + qsz);
size = roundup2(size, VRING_ALIGN);
/* constant 3 below = vu_flags, vu_idx, vu_avail_event */
size += sizeof(uint16_t) * 3 + sizeof(struct virtio_used) * qsz;
size = roundup2(size, VRING_ALIGN);
return (size);
}
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 */
};
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 */
uint32_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->va_idx */
uint16_t vq_save_used; /* saved vq_used->vu_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!) */
volatile struct virtio_desc *vq_desc; /* descriptor array */
volatile struct vring_avail *vq_avail; /* the "avail" ring */
volatile struct vring_used *vq_used; /* the "used" ring */
};
/* as noted above, these are sort of backwards, name-wise */
#define VQ_AVAIL_EVENT_IDX(vq) \
(*(volatile uint16_t *)&(vq)->vq_used->vu_ring[(vq)->vq_qsize])
#define VQ_USED_EVENT_IDX(vq) \
((vq)->vq_avail->va_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->va_idx);
}
/*
* Called by virtio driver as it starts processing chains. Each
* completed chain (obtained from vq_getchain()) is released by
* calling vq_relchain(), then when all are done, vq_endchains()
* can tell if / how-many chains were processed and know whether
* and how to generate an interrupt.
*/
static inline void
vq_startchains(struct vqueue_info *vq)
{
vq->vq_save_used = vq->vq_used->vu_idx;
}
/*
* Deliver an interrupt to 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)
{
if (vs->vs_flags & VIRTIO_USE_MSIX)
pci_generate_msix(vs->vs_pi, vq->vq_msix_idx);
else {
vs->vs_isr |= VTCFG_ISR_QUEUES;
pci_generate_msi(vs->vs_pi, 0);
}
}
struct iovec;
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 n_iov, uint16_t *flags);
void vq_relchain(struct vqueue_info *vq, uint32_t iolen);
void vq_endchains(struct vqueue_info *vq, int used_all_avail);
uint64_t vi_pci_read(struct vmctx *ctx, int vcpu, struct pci_devinst *pi,
int baridx, uint64_t offset, int size);
void vi_pci_write(struct vmctx *ctx, int vcpu, struct pci_devinst *pi,
int baridx, uint64_t offset, int size, uint64_t value);
#endif /* _VIRTIO_H_ */
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