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qemu/hw/virtio.c

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/*
* 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"
/* from Linux's linux/virtio_pci.h */
/* A 32-bit r/o bitmask of the features supported by the host */
#define VIRTIO_PCI_HOST_FEATURES 0
/* A 32-bit r/w bitmask of features activated by the guest */
#define VIRTIO_PCI_GUEST_FEATURES 4
/* A 32-bit r/w PFN for the currently selected queue */
#define VIRTIO_PCI_QUEUE_PFN 8
/* A 16-bit r/o queue size for the currently selected queue */
#define VIRTIO_PCI_QUEUE_NUM 12
/* A 16-bit r/w queue selector */
#define VIRTIO_PCI_QUEUE_SEL 14
/* A 16-bit r/w queue notifier */
#define VIRTIO_PCI_QUEUE_NOTIFY 16
/* An 8-bit device status register. */
#define VIRTIO_PCI_STATUS 18
/* An 8-bit r/o interrupt status register. Reading the value will return the
* current contents of the ISR and will also clear it. This is effectively
* a read-and-acknowledge. */
#define VIRTIO_PCI_ISR 19
#define VIRTIO_PCI_CONFIG 20
/* Virtio ABI version, if we increment this, we break the guest driver. */
#define VIRTIO_PCI_ABI_VERSION 0
/* How many bits to shift physical queue address written to QUEUE_PFN.
* 12 is historical, and due to x86 page size. */
#define VIRTIO_PCI_QUEUE_ADDR_SHIFT 12
/* 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.
*/
#define wmb() do { } while (0)
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;
uint32_t pfn;
uint16_t last_avail_idx;
int inuse;
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->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(VirtQueue *vq, int i)
{
target_phys_addr_t pa;
pa = vq->vring.desc + sizeof(VRingDesc) * i + offsetof(VRingDesc, addr);
return ldq_phys(pa);
}
static inline uint32_t vring_desc_len(VirtQueue *vq, int i)
{
target_phys_addr_t pa;
pa = vq->vring.desc + sizeof(VRingDesc) * i + offsetof(VRingDesc, len);
return ldl_phys(pa);
}
static inline uint16_t vring_desc_flags(VirtQueue *vq, int i)
{
target_phys_addr_t pa;
pa = vq->vring.desc + sizeof(VRingDesc) * i + offsetof(VRingDesc, flags);
return lduw_phys(pa);
}
static inline uint16_t vring_desc_next(VirtQueue *vq, int i)
{
target_phys_addr_t pa;
pa = vq->vring.desc + 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(VirtQueue *vq, unsigned int i)
{
unsigned int next;
/* If this descriptor says it doesn't chain, we're done. */
if (!(vring_desc_flags(vq, i) & VRING_DESC_F_NEXT))
return vq->vring.num;
/* Check they're not leading us off end of descriptors. */
next = vring_desc_next(vq, i);
/* Make sure compiler knows to grab that: we don't want it changing! */
wmb();
if (next >= vq->vring.num) {
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 num_bufs, in_total, out_total;
idx = vq->last_avail_idx;
num_bufs = in_total = out_total = 0;
while (virtqueue_num_heads(vq, idx)) {
int i;
i = virtqueue_get_head(vq, idx++);
do {
/* If we've got too many, that implies a descriptor loop. */
if (++num_bufs > vq->vring.num) {
fprintf(stderr, "Looped descriptor");
exit(1);
}
if (vring_desc_flags(vq, i) & VRING_DESC_F_WRITE) {
if (in_bytes > 0 &&
(in_total += vring_desc_len(vq, i)) >= in_bytes)
return 1;
} else {
if (out_bytes > 0 &&
(out_total += vring_desc_len(vq, i)) >= out_bytes)
return 1;
}
} while ((i = virtqueue_next_desc(vq, i)) != vq->vring.num);
}
return 0;
}
int virtqueue_pop(VirtQueue *vq, VirtQueueElement *elem)
{
unsigned int i, head;
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;
i = head = virtqueue_get_head(vq, vq->last_avail_idx++);
do {
struct iovec *sg;
int is_write = 0;
if (vring_desc_flags(vq, i) & VRING_DESC_F_WRITE) {
elem->in_addr[elem->in_num] = vring_desc_addr(vq, 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(vq, i);
len = sg->iov_len;
sg->iov_base = cpu_physical_memory_map(vring_desc_addr(vq, 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) > vq->vring.num) {
fprintf(stderr, "Looped descriptor");
exit(1);
}
} while ((i = virtqueue_next_desc(vq, i)) != vq->vring.num);
elem->index = head;
vq->inuse++;
return elem->in_num + elem->out_num;
}
/* virtio device */
static VirtIODevice *to_virtio_device(PCIDevice *pci_dev)
{
return (VirtIODevice *)pci_dev;
}
static void virtio_update_irq(VirtIODevice *vdev)
{
qemu_set_irq(vdev->pci_dev.irq[0], vdev->isr & 1);
}
static 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;
virtio_update_irq(vdev);
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].pfn = 0;
}
}
static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
{
VirtIODevice *vdev = to_virtio_device(opaque);
ram_addr_t pa;
addr -= vdev->addr;
switch (addr) {
case VIRTIO_PCI_GUEST_FEATURES:
/* Guest does not negotiate properly? We have to assume nothing. */
if (val & (1 << VIRTIO_F_BAD_FEATURE)) {
if (vdev->bad_features)
val = vdev->bad_features(vdev);
else
val = 0;
}
if (vdev->set_features)
vdev->set_features(vdev, val);
vdev->features = val;
break;
case VIRTIO_PCI_QUEUE_PFN:
pa = (ram_addr_t)val << VIRTIO_PCI_QUEUE_ADDR_SHIFT;
vdev->vq[vdev->queue_sel].pfn = val;
if (pa == 0) {
virtio_reset(vdev);
} else {
virtqueue_init(&vdev->vq[vdev->queue_sel], pa);
}
break;
case VIRTIO_PCI_QUEUE_SEL:
if (val < VIRTIO_PCI_QUEUE_MAX)
vdev->queue_sel = val;
break;
case VIRTIO_PCI_QUEUE_NOTIFY:
if (val < VIRTIO_PCI_QUEUE_MAX && vdev->vq[val].vring.desc)
vdev->vq[val].handle_output(vdev, &vdev->vq[val]);
break;
case VIRTIO_PCI_STATUS:
vdev->status = val & 0xFF;
if (vdev->status == 0)
virtio_reset(vdev);
break;
}
}
static uint32_t virtio_ioport_read(void *opaque, uint32_t addr)
{
VirtIODevice *vdev = to_virtio_device(opaque);
uint32_t ret = 0xFFFFFFFF;
addr -= vdev->addr;
switch (addr) {
case VIRTIO_PCI_HOST_FEATURES:
ret = vdev->get_features(vdev);
ret |= (1 << VIRTIO_F_NOTIFY_ON_EMPTY) | (1 << VIRTIO_F_BAD_FEATURE);
break;
case VIRTIO_PCI_GUEST_FEATURES:
ret = vdev->features;
break;
case VIRTIO_PCI_QUEUE_PFN:
ret = vdev->vq[vdev->queue_sel].pfn;
break;
case VIRTIO_PCI_QUEUE_NUM:
ret = vdev->vq[vdev->queue_sel].vring.num;
break;
case VIRTIO_PCI_QUEUE_SEL:
ret = vdev->queue_sel;
break;
case VIRTIO_PCI_STATUS:
ret = vdev->status;
break;
case VIRTIO_PCI_ISR:
/* reading from the ISR also clears it. */
ret = vdev->isr;
vdev->isr = 0;
virtio_update_irq(vdev);
break;
default:
break;
}
return ret;
}
static uint32_t virtio_config_readb(void *opaque, uint32_t addr)
{
VirtIODevice *vdev = opaque;
uint8_t val;
vdev->get_config(vdev, vdev->config);
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
static uint32_t virtio_config_readw(void *opaque, uint32_t addr)
{
VirtIODevice *vdev = opaque;
uint16_t val;
vdev->get_config(vdev, vdev->config);
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
static uint32_t virtio_config_readl(void *opaque, uint32_t addr)
{
VirtIODevice *vdev = opaque;
uint32_t val;
vdev->get_config(vdev, vdev->config);
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
if (addr > (vdev->config_len - sizeof(val)))
return (uint32_t)-1;
memcpy(&val, vdev->config + addr, sizeof(val));
return val;
}
static void virtio_config_writeb(void *opaque, uint32_t addr, uint32_t data)
{
VirtIODevice *vdev = opaque;
uint8_t val = data;
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
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);
}
static void virtio_config_writew(void *opaque, uint32_t addr, uint32_t data)
{
VirtIODevice *vdev = opaque;
uint16_t val = data;
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
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);
}
static void virtio_config_writel(void *opaque, uint32_t addr, uint32_t data)
{
VirtIODevice *vdev = opaque;
uint32_t val = data;
addr -= vdev->addr + VIRTIO_PCI_CONFIG;
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);
}
static void virtio_map(PCIDevice *pci_dev, int region_num,
uint32_t addr, uint32_t size, int type)
{
VirtIODevice *vdev = to_virtio_device(pci_dev);
int i;
vdev->addr = addr;
for (i = 0; i < 3; i++) {
register_ioport_write(addr, 20, 1 << i, virtio_ioport_write, vdev);
register_ioport_read(addr, 20, 1 << i, virtio_ioport_read, vdev);
}
if (vdev->config_len) {
register_ioport_write(addr + 20, vdev->config_len, 1,
virtio_config_writeb, vdev);
register_ioport_write(addr + 20, vdev->config_len, 2,
virtio_config_writew, vdev);
register_ioport_write(addr + 20, vdev->config_len, 4,
virtio_config_writel, vdev);
register_ioport_read(addr + 20, vdev->config_len, 1,
virtio_config_readb, vdev);
register_ioport_read(addr + 20, vdev->config_len, 2,
virtio_config_readw, vdev);
register_ioport_read(addr + 20, vdev->config_len, 4,
virtio_config_readl, vdev);
vdev->get_config(vdev, vdev->config);
}
}
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_update_irq(vdev);
}
void virtio_notify_config(VirtIODevice *vdev)
{
if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))
return;
vdev->isr |= 0x03;
virtio_update_irq(vdev);
}
void virtio_save(VirtIODevice *vdev, QEMUFile *f)
{
int i;
pci_device_save(&vdev->pci_dev, f);
qemu_put_be32s(f, &vdev->addr);
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_be32s(f, &vdev->vq[i].pfn);
qemu_put_be16s(f, &vdev->vq[i].last_avail_idx);
}
}
void virtio_load(VirtIODevice *vdev, QEMUFile *f)
{
int num, i;
pci_device_load(&vdev->pci_dev, f);
qemu_get_be32s(f, &vdev->addr);
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);
qemu_get_be32s(f, &vdev->vq[i].pfn);
qemu_get_be16s(f, &vdev->vq[i].last_avail_idx);
if (vdev->vq[i].pfn) {
target_phys_addr_t pa;
pa = (ram_addr_t)vdev->vq[i].pfn << VIRTIO_PCI_QUEUE_ADDR_SHIFT;
virtqueue_init(&vdev->vq[i], pa);
}
}
virtio_update_irq(vdev);
}
void virtio_cleanup(VirtIODevice *vdev)
{
if (vdev->config)
qemu_free(vdev->config);
qemu_free(vdev->vq);
}
VirtIODevice *virtio_init_pci(PCIDevice *pci_dev, const char *name,
uint16_t vendor, uint16_t device,
uint16_t subvendor, uint16_t subdevice,
uint16_t class_code, uint8_t pif,
size_t config_size)
{
VirtIODevice *vdev;
uint8_t *config;
uint32_t size;
vdev = to_virtio_device(pci_dev);
vdev->status = 0;
vdev->isr = 0;
vdev->queue_sel = 0;
vdev->vq = qemu_mallocz(sizeof(VirtQueue) * VIRTIO_PCI_QUEUE_MAX);
config = pci_dev->config;
pci_config_set_vendor_id(config, vendor);
pci_config_set_device_id(config, device);
config[0x08] = VIRTIO_PCI_ABI_VERSION;
config[0x09] = pif;
pci_config_set_class(config, class_code);
config[PCI_HEADER_TYPE] = PCI_HEADER_TYPE_NORMAL;
config[0x2c] = subvendor & 0xFF;
config[0x2d] = (subvendor >> 8) & 0xFF;
config[0x2e] = subdevice & 0xFF;
config[0x2f] = (subdevice >> 8) & 0xFF;
config[0x3d] = 1;
vdev->name = name;
vdev->config_len = config_size;
if (vdev->config_len)
vdev->config = qemu_mallocz(config_size);
else
vdev->config = NULL;
size = 20 + config_size;
if (size & (size-1))
size = 1 << qemu_fls(size);
pci_register_io_region(pci_dev, 0, size, PCI_ADDRESS_SPACE_IO,
virtio_map);
qemu_register_reset(virtio_reset, vdev);
return vdev;
}
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