qemu/hw/virtio.c
Michael S. Tsirkin 79758e95d7 qemu/virtio: make wmb compiler barrier + comments
wmb must be at least a compiler barrier, even without SMP.
Further, we likely need some rmb()/mb() as well:
I have not audited the code but lguest has mb(),
add a comment for now.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2009-10-30 08:39:34 -05:00

729 lines
19 KiB
C

/*
* Virtio Support
*
* Copyright IBM, Corp. 2007
*
* Authors:
* Anthony Liguori <aliguori@us.ibm.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include <inttypes.h>
#include "virtio.h"
#include "sysemu.h"
/* The alignment to use between consumer and producer parts of vring.
* x86 pagesize again. */
#define VIRTIO_PCI_VRING_ALIGN 4096
/* QEMU doesn't strictly need write barriers since everything runs in
* lock-step. We'll leave the calls to wmb() in though to make it obvious for
* KVM or if kqemu gets SMP support.
* In any case, we must prevent the compiler from reordering the code.
* TODO: we likely need some rmb()/mb() as well.
*/
#define wmb() __asm__ __volatile__("": : :"memory")
typedef struct VRingDesc
{
uint64_t addr;
uint32_t len;
uint16_t flags;
uint16_t next;
} VRingDesc;
typedef struct VRingAvail
{
uint16_t flags;
uint16_t idx;
uint16_t ring[0];
} VRingAvail;
typedef struct VRingUsedElem
{
uint32_t id;
uint32_t len;
} VRingUsedElem;
typedef struct VRingUsed
{
uint16_t flags;
uint16_t idx;
VRingUsedElem ring[0];
} VRingUsed;
typedef struct VRing
{
unsigned int num;
target_phys_addr_t desc;
target_phys_addr_t avail;
target_phys_addr_t used;
} VRing;
struct VirtQueue
{
VRing vring;
target_phys_addr_t pa;
uint16_t last_avail_idx;
int inuse;
uint16_t vector;
void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
};
#define VIRTIO_PCI_QUEUE_MAX 16
/* virt queue functions */
static void virtqueue_init(VirtQueue *vq)
{
target_phys_addr_t pa = vq->pa;
vq->vring.desc = pa;
vq->vring.avail = pa + vq->vring.num * sizeof(VRingDesc);
vq->vring.used = vring_align(vq->vring.avail +
offsetof(VRingAvail, ring[vq->vring.num]),
VIRTIO_PCI_VRING_ALIGN);
}
static inline uint64_t vring_desc_addr(target_phys_addr_t desc_pa, int i)
{
target_phys_addr_t pa;
pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, addr);
return ldq_phys(pa);
}
static inline uint32_t vring_desc_len(target_phys_addr_t desc_pa, int i)
{
target_phys_addr_t pa;
pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, len);
return ldl_phys(pa);
}
static inline uint16_t vring_desc_flags(target_phys_addr_t desc_pa, int i)
{
target_phys_addr_t pa;
pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, flags);
return lduw_phys(pa);
}
static inline uint16_t vring_desc_next(target_phys_addr_t desc_pa, int i)
{
target_phys_addr_t pa;
pa = desc_pa + sizeof(VRingDesc) * i + offsetof(VRingDesc, next);
return lduw_phys(pa);
}
static inline uint16_t vring_avail_flags(VirtQueue *vq)
{
target_phys_addr_t pa;
pa = vq->vring.avail + offsetof(VRingAvail, flags);
return lduw_phys(pa);
}
static inline uint16_t vring_avail_idx(VirtQueue *vq)
{
target_phys_addr_t pa;
pa = vq->vring.avail + offsetof(VRingAvail, idx);
return lduw_phys(pa);
}
static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
{
target_phys_addr_t pa;
pa = vq->vring.avail + offsetof(VRingAvail, ring[i]);
return lduw_phys(pa);
}
static inline void vring_used_ring_id(VirtQueue *vq, int i, uint32_t val)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, ring[i].id);
stl_phys(pa, val);
}
static inline void vring_used_ring_len(VirtQueue *vq, int i, uint32_t val)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, ring[i].len);
stl_phys(pa, val);
}
static uint16_t vring_used_idx(VirtQueue *vq)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, idx);
return lduw_phys(pa);
}
static inline void vring_used_idx_increment(VirtQueue *vq, uint16_t val)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, idx);
stw_phys(pa, vring_used_idx(vq) + val);
}
static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, flags);
stw_phys(pa, lduw_phys(pa) | mask);
}
static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
{
target_phys_addr_t pa;
pa = vq->vring.used + offsetof(VRingUsed, flags);
stw_phys(pa, lduw_phys(pa) & ~mask);
}
void virtio_queue_set_notification(VirtQueue *vq, int enable)
{
if (enable)
vring_used_flags_unset_bit(vq, VRING_USED_F_NO_NOTIFY);
else
vring_used_flags_set_bit(vq, VRING_USED_F_NO_NOTIFY);
}
int virtio_queue_ready(VirtQueue *vq)
{
return vq->vring.avail != 0;
}
int virtio_queue_empty(VirtQueue *vq)
{
return vring_avail_idx(vq) == vq->last_avail_idx;
}
void virtqueue_fill(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len, unsigned int idx)
{
unsigned int offset;
int i;
offset = 0;
for (i = 0; i < elem->in_num; i++) {
size_t size = MIN(len - offset, elem->in_sg[i].iov_len);
cpu_physical_memory_unmap(elem->in_sg[i].iov_base,
elem->in_sg[i].iov_len,
1, size);
offset += elem->in_sg[i].iov_len;
}
for (i = 0; i < elem->out_num; i++)
cpu_physical_memory_unmap(elem->out_sg[i].iov_base,
elem->out_sg[i].iov_len,
0, elem->out_sg[i].iov_len);
idx = (idx + vring_used_idx(vq)) % vq->vring.num;
/* Get a pointer to the next entry in the used ring. */
vring_used_ring_id(vq, idx, elem->index);
vring_used_ring_len(vq, idx, len);
}
void virtqueue_flush(VirtQueue *vq, unsigned int count)
{
/* Make sure buffer is written before we update index. */
wmb();
vring_used_idx_increment(vq, count);
vq->inuse -= count;
}
void virtqueue_push(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
virtqueue_fill(vq, elem, len, 0);
virtqueue_flush(vq, 1);
}
static int virtqueue_num_heads(VirtQueue *vq, unsigned int idx)
{
uint16_t num_heads = vring_avail_idx(vq) - idx;
/* Check it isn't doing very strange things with descriptor numbers. */
if (num_heads > vq->vring.num) {
fprintf(stderr, "Guest moved used index from %u to %u",
idx, vring_avail_idx(vq));
exit(1);
}
return num_heads;
}
static unsigned int virtqueue_get_head(VirtQueue *vq, unsigned int idx)
{
unsigned int head;
/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
head = vring_avail_ring(vq, idx % vq->vring.num);
/* If their number is silly, that's a fatal mistake. */
if (head >= vq->vring.num) {
fprintf(stderr, "Guest says index %u is available", head);
exit(1);
}
return head;
}
static unsigned virtqueue_next_desc(target_phys_addr_t desc_pa,
unsigned int i, unsigned int max)
{
unsigned int next;
/* If this descriptor says it doesn't chain, we're done. */
if (!(vring_desc_flags(desc_pa, i) & VRING_DESC_F_NEXT))
return max;
/* Check they're not leading us off end of descriptors. */
next = vring_desc_next(desc_pa, i);
/* Make sure compiler knows to grab that: we don't want it changing! */
wmb();
if (next >= max) {
fprintf(stderr, "Desc next is %u", next);
exit(1);
}
return next;
}
int virtqueue_avail_bytes(VirtQueue *vq, int in_bytes, int out_bytes)
{
unsigned int idx;
int total_bufs, in_total, out_total;
idx = vq->last_avail_idx;
total_bufs = in_total = out_total = 0;
while (virtqueue_num_heads(vq, idx)) {
unsigned int max, num_bufs, indirect = 0;
target_phys_addr_t desc_pa;
int i;
max = vq->vring.num;
num_bufs = total_bufs;
i = virtqueue_get_head(vq, idx++);
desc_pa = vq->vring.desc;
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
fprintf(stderr, "Invalid size for indirect buffer table\n");
exit(1);
}
/* If we've got too many, that implies a descriptor loop. */
if (num_bufs >= max) {
fprintf(stderr, "Looped descriptor");
exit(1);
}
/* loop over the indirect descriptor table */
indirect = 1;
max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
num_bufs = i = 0;
desc_pa = vring_desc_addr(desc_pa, i);
}
do {
/* If we've got too many, that implies a descriptor loop. */
if (++num_bufs > max) {
fprintf(stderr, "Looped descriptor");
exit(1);
}
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
if (in_bytes > 0 &&
(in_total += vring_desc_len(desc_pa, i)) >= in_bytes)
return 1;
} else {
if (out_bytes > 0 &&
(out_total += vring_desc_len(desc_pa, i)) >= out_bytes)
return 1;
}
} while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
if (!indirect)
total_bufs = num_bufs;
else
total_bufs++;
}
return 0;
}
int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
{
unsigned int i, head, max;
target_phys_addr_t desc_pa = vq->vring.desc;
target_phys_addr_t len;
if (!virtqueue_num_heads(vq, vq->last_avail_idx))
return 0;
/* When we start there are none of either input nor output. */
elem->out_num = elem->in_num = 0;
max = vq->vring.num;
i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_INDIRECT) {
if (vring_desc_len(desc_pa, i) % sizeof(VRingDesc)) {
fprintf(stderr, "Invalid size for indirect buffer table\n");
exit(1);
}
/* loop over the indirect descriptor table */
max = vring_desc_len(desc_pa, i) / sizeof(VRingDesc);
desc_pa = vring_desc_addr(desc_pa, i);
i = 0;
}
do {
struct iovec *sg;
int is_write = 0;
if (vring_desc_flags(desc_pa, i) & VRING_DESC_F_WRITE) {
elem->in_addr[elem->in_num] = vring_desc_addr(desc_pa, i);
sg = &elem->in_sg[elem->in_num++];
is_write = 1;
} else
sg = &elem->out_sg[elem->out_num++];
/* Grab the first descriptor, and check it's OK. */
sg->iov_len = vring_desc_len(desc_pa, i);
len = sg->iov_len;
sg->iov_base = cpu_physical_memory_map(vring_desc_addr(desc_pa, i),
&len, is_write);
if (sg->iov_base == NULL || len != sg->iov_len) {
fprintf(stderr, "virtio: trying to map MMIO memory\n");
exit(1);
}
/* If we've got too many, that implies a descriptor loop. */
if ((elem->in_num + elem->out_num) > max) {
fprintf(stderr, "Looped descriptor");
exit(1);
}
} while ((i = virtqueue_next_desc(desc_pa, i, max)) != max);
elem->index = head;
vq->inuse++;
return elem->in_num + elem->out_num;
}
/* virtio device */
static void virtio_notify_vector(VirtIODevice *vdev, uint16_t vector)
{
if (vdev->binding->notify) {
vdev->binding->notify(vdev->binding_opaque, vector);
}
}
void virtio_update_irq(VirtIODevice *vdev)
{
virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
}
void virtio_reset(void *opaque)
{
VirtIODevice *vdev = opaque;
int i;
if (vdev->reset)
vdev->reset(vdev);
vdev->features = 0;
vdev->queue_sel = 0;
vdev->status = 0;
vdev->isr = 0;
vdev->config_vector = VIRTIO_NO_VECTOR;
virtio_notify_vector(vdev, vdev->config_vector);
for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
vdev->vq[i].vring.desc = 0;
vdev->vq[i].vring.avail = 0;
vdev->vq[i].vring.used = 0;
vdev->vq[i].last_avail_idx = 0;
vdev->vq[i].pa = 0;
vdev->vq[i].vector = VIRTIO_NO_VECTOR;
}
}
uint32_t virtio_config_readb(VirtIODevice *vdev, uint32_t addr)
{
uint8_t val;
vdev->get_config(vdev, vdev->config);
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)
{
uint16_t val;
vdev->get_config(vdev, vdev->config);
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)
{
uint32_t val;
vdev->get_config(vdev, vdev->config);
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
void virtio_config_writeb(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
uint8_t val = data;
if (addr > (vdev->config_len - sizeof(val)))
return;
memcpy(vdev->config + addr, &val, sizeof(val));
if (vdev->set_config)
vdev->set_config(vdev, vdev->config);
}
void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
uint16_t val = data;
if (addr > (vdev->config_len - sizeof(val)))
return;
memcpy(vdev->config + addr, &val, sizeof(val));
if (vdev->set_config)
vdev->set_config(vdev, vdev->config);
}
void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
{
uint32_t val = data;
if (addr > (vdev->config_len - sizeof(val)))
return;
memcpy(vdev->config + addr, &val, sizeof(val));
if (vdev->set_config)
vdev->set_config(vdev, vdev->config);
}
void virtio_queue_set_addr(VirtIODevice *vdev, int n, target_phys_addr_t addr)
{
vdev->vq[n].pa = addr;
virtqueue_init(&vdev->vq[n]);
}
target_phys_addr_t virtio_queue_get_addr(VirtIODevice *vdev, int n)
{
return vdev->vq[n].pa;
}
int virtio_queue_get_num(VirtIODevice *vdev, int n)
{
return vdev->vq[n].vring.num;
}
void virtio_queue_notify(VirtIODevice *vdev, int n)
{
if (n < VIRTIO_PCI_QUEUE_MAX && vdev->vq[n].vring.desc) {
vdev->vq[n].handle_output(vdev, &vdev->vq[n]);
}
}
uint16_t virtio_queue_vector(VirtIODevice *vdev, int n)
{
return n < VIRTIO_PCI_QUEUE_MAX ? vdev->vq[n].vector :
VIRTIO_NO_VECTOR;
}
void virtio_queue_set_vector(VirtIODevice *vdev, int n, uint16_t vector)
{
if (n < VIRTIO_PCI_QUEUE_MAX)
vdev->vq[n].vector = vector;
}
VirtQueue *virtio_add_queue(VirtIODevice *vdev, int queue_size,
void (*handle_output)(VirtIODevice *, VirtQueue *))
{
int i;
for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
}
if (i == VIRTIO_PCI_QUEUE_MAX || queue_size > VIRTQUEUE_MAX_SIZE)
abort();
vdev->vq[i].vring.num = queue_size;
vdev->vq[i].handle_output = handle_output;
return &vdev->vq[i];
}
void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
{
/* Always notify when queue is empty (when feature acknowledge) */
if ((vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT) &&
(!(vdev->features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) ||
(vq->inuse || vring_avail_idx(vq) != vq->last_avail_idx)))
return;
vdev->isr |= 0x01;
virtio_notify_vector(vdev, vq->vector);
}
void virtio_notify_config(VirtIODevice *vdev)
{
if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
return;
vdev->isr |= 0x03;
virtio_notify_vector(vdev, vdev->config_vector);
}
void virtio_save(VirtIODevice *vdev, QEMUFile *f)
{
int i;
if (vdev->binding->save_config)
vdev->binding->save_config(vdev->binding_opaque, f);
qemu_put_8s(f, &vdev->status);
qemu_put_8s(f, &vdev->isr);
qemu_put_be16s(f, &vdev->queue_sel);
qemu_put_be32s(f, &vdev->features);
qemu_put_be32(f, vdev->config_len);
qemu_put_buffer(f, vdev->config, vdev->config_len);
for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
}
qemu_put_be32(f, i);
for (i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++) {
if (vdev->vq[i].vring.num == 0)
break;
qemu_put_be32(f, vdev->vq[i].vring.num);
qemu_put_be64(f, vdev->vq[i].pa);
qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
if (vdev->binding->save_queue)
vdev->binding->save_queue(vdev->binding_opaque, i, f);
}
}
int virtio_load(VirtIODevice *vdev, QEMUFile *f)
{
int num, i, ret;
if (vdev->binding->load_config) {
ret = vdev->binding->load_config(vdev->binding_opaque, f);
if (ret)
return ret;
}
qemu_get_8s(f, &vdev->status);
qemu_get_8s(f, &vdev->isr);
qemu_get_be16s(f, &vdev->queue_sel);
qemu_get_be32s(f, &vdev->features);
vdev->config_len = qemu_get_be32(f);
qemu_get_buffer(f, vdev->config, vdev->config_len);
num = qemu_get_be32(f);
for (i = 0; i < num; i++) {
vdev->vq[i].vring.num = qemu_get_be32(f);
vdev->vq[i].pa = qemu_get_be64(f);
qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
if (vdev->vq[i].pa) {
virtqueue_init(&vdev->vq[i]);
}
if (vdev->binding->load_queue) {
ret = vdev->binding->load_queue(vdev->binding_opaque, i, f);
if (ret)
return ret;
}
}
virtio_notify_vector(vdev, VIRTIO_NO_VECTOR);
return 0;
}
void virtio_cleanup(VirtIODevice *vdev)
{
if (vdev->config)
qemu_free(vdev->config);
qemu_free(vdev->vq);
}
VirtIODevice *virtio_common_init(const char *name, uint16_t device_id,
size_t config_size, size_t struct_size)
{
VirtIODevice *vdev;
int i;
vdev = qemu_mallocz(struct_size);
vdev->device_id = device_id;
vdev->status = 0;
vdev->isr = 0;
vdev->queue_sel = 0;
vdev->config_vector = VIRTIO_NO_VECTOR;
vdev->vq = qemu_mallocz(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
for(i = 0; i < VIRTIO_PCI_QUEUE_MAX; i++)
vdev->vq[i].vector = VIRTIO_NO_VECTOR;
vdev->name = name;
vdev->config_len = config_size;
if (vdev->config_len)
vdev->config = qemu_mallocz(config_size);
else
vdev->config = NULL;
return vdev;
}
void virtio_bind_device(VirtIODevice *vdev, const VirtIOBindings *binding,
void *opaque)
{
vdev->binding = binding;
vdev->binding_opaque = opaque;
}