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qemu/hw/syborg_virtio.c
Alex Williamson a697a334b3 virtio-net: Introduce a new bottom half packet TX 
Based on a patch from Mark McLoughlin, this patch introduces a new
bottom half packet transmitter that avoids the latency imposed by
the tx_timer approach.  Rather than scheduling a timer when a TX
packet comes in, schedule a bottom half to be run from the iothread.
The bottom half handler first attempts to flush the queue with
notification disabled (this is where we could race with a guest
without txburst).  If we flush a full burst, reschedule immediately.
If we send short of a full burst, try to re-enable notification.
To avoid a race with TXs that may have occurred, we must then
flush again.  If we find some packets to send, the guest it probably
active, so we can reschedule again.

tx_timer and tx_bh are mutually exclusive, so we can re-use the
tx_waiting flag to indicate one or the other needs to be setup.
This allows us to seamlessly migrate between timer and bh TX
handling.

The bottom half handler becomes the new default and we add a new
tx= option to virtio-net-pci.  Usage:

-device virtio-net-pci,tx=timer # select timer mitigation vs "bh"

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2010-09-07 20:29:29 +03:00

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/*
* Virtio Syborg bindings
*
* Copyright (c) 2009 CodeSourcery
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "syborg.h"
#include "sysbus.h"
#include "virtio.h"
#include "virtio-net.h"
#include "sysemu.h"
//#define DEBUG_SYBORG_VIRTIO
#ifdef DEBUG_SYBORG_VIRTIO
#define DPRINTF(fmt, ...) \
do { printf("syborg_virtio: " fmt , ## __VA_ARGS__); } while (0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "syborg_virtio: error: " fmt , ## __VA_ARGS__); \
exit(1);} while (0)
#else
#define DPRINTF(fmt, ...) do {} while(0)
#define BADF(fmt, ...) \
do { fprintf(stderr, "syborg_virtio: error: " fmt , ## __VA_ARGS__);} while (0)
#endif
enum {
SYBORG_VIRTIO_ID = 0,
SYBORG_VIRTIO_DEVTYPE = 1,
SYBORG_VIRTIO_HOST_FEATURES = 2,
SYBORG_VIRTIO_GUEST_FEATURES = 3,
SYBORG_VIRTIO_QUEUE_BASE = 4,
SYBORG_VIRTIO_QUEUE_NUM = 5,
SYBORG_VIRTIO_QUEUE_SEL = 6,
SYBORG_VIRTIO_QUEUE_NOTIFY = 7,
SYBORG_VIRTIO_STATUS = 8,
SYBORG_VIRTIO_INT_ENABLE = 9,
SYBORG_VIRTIO_INT_STATUS = 10
};
#define SYBORG_VIRTIO_CONFIG 0x100
/* Device independent interface. */
typedef struct {
SysBusDevice busdev;
VirtIODevice *vdev;
qemu_irq irq;
uint32_t int_enable;
uint32_t id;
NICConf nic;
uint32_t host_features;
virtio_net_conf net;
} SyborgVirtIOProxy;
static uint32_t syborg_virtio_readl(void *opaque, target_phys_addr_t offset)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
uint32_t ret;
DPRINTF("readl 0x%x\n", (int)offset);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_readl(vdev, offset - SYBORG_VIRTIO_CONFIG);
}
switch(offset >> 2) {
case SYBORG_VIRTIO_ID:
ret = SYBORG_ID_VIRTIO;
break;
case SYBORG_VIRTIO_DEVTYPE:
ret = s->id;
break;
case SYBORG_VIRTIO_HOST_FEATURES:
ret = s->host_features;
break;
case SYBORG_VIRTIO_GUEST_FEATURES:
ret = vdev->guest_features;
break;
case SYBORG_VIRTIO_QUEUE_BASE:
ret = virtio_queue_get_addr(vdev, vdev->queue_sel);
break;
case SYBORG_VIRTIO_QUEUE_NUM:
ret = virtio_queue_get_num(vdev, vdev->queue_sel);
break;
case SYBORG_VIRTIO_QUEUE_SEL:
ret = vdev->queue_sel;
break;
case SYBORG_VIRTIO_STATUS:
ret = vdev->status;
break;
case SYBORG_VIRTIO_INT_ENABLE:
ret = s->int_enable;
break;
case SYBORG_VIRTIO_INT_STATUS:
ret = vdev->isr;
break;
default:
BADF("Bad read offset 0x%x\n", (int)offset);
return 0;
}
return ret;
}
static void syborg_virtio_writel(void *opaque, target_phys_addr_t offset,
uint32_t value)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
DPRINTF("writel 0x%x = 0x%x\n", (int)offset, value);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_writel(vdev, offset - SYBORG_VIRTIO_CONFIG,
value);
}
switch (offset >> 2) {
case SYBORG_VIRTIO_GUEST_FEATURES:
if (vdev->set_features)
vdev->set_features(vdev, value);
vdev->guest_features = value;
break;
case SYBORG_VIRTIO_QUEUE_BASE:
if (value == 0)
virtio_reset(vdev);
else
virtio_queue_set_addr(vdev, vdev->queue_sel, value);
break;
case SYBORG_VIRTIO_QUEUE_SEL:
if (value < VIRTIO_PCI_QUEUE_MAX)
vdev->queue_sel = value;
break;
case SYBORG_VIRTIO_QUEUE_NOTIFY:
virtio_queue_notify(vdev, value);
break;
case SYBORG_VIRTIO_STATUS:
virtio_set_status(vdev, value & 0xFF);
if (vdev->status == 0)
virtio_reset(vdev);
break;
case SYBORG_VIRTIO_INT_ENABLE:
s->int_enable = value;
virtio_update_irq(vdev);
break;
case SYBORG_VIRTIO_INT_STATUS:
vdev->isr &= ~value;
virtio_update_irq(vdev);
break;
default:
BADF("Bad write offset 0x%x\n", (int)offset);
break;
}
}
static uint32_t syborg_virtio_readw(void *opaque, target_phys_addr_t offset)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
DPRINTF("readw 0x%x\n", (int)offset);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_readw(vdev, offset - SYBORG_VIRTIO_CONFIG);
}
BADF("Bad halfword read offset 0x%x\n", (int)offset);
return -1;
}
static void syborg_virtio_writew(void *opaque, target_phys_addr_t offset,
uint32_t value)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
DPRINTF("writew 0x%x = 0x%x\n", (int)offset, value);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_writew(vdev, offset - SYBORG_VIRTIO_CONFIG,
value);
}
BADF("Bad halfword write offset 0x%x\n", (int)offset);
}
static uint32_t syborg_virtio_readb(void *opaque, target_phys_addr_t offset)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
DPRINTF("readb 0x%x\n", (int)offset);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_readb(vdev, offset - SYBORG_VIRTIO_CONFIG);
}
BADF("Bad byte read offset 0x%x\n", (int)offset);
return -1;
}
static void syborg_virtio_writeb(void *opaque, target_phys_addr_t offset,
uint32_t value)
{
SyborgVirtIOProxy *s = opaque;
VirtIODevice *vdev = s->vdev;
DPRINTF("writeb 0x%x = 0x%x\n", (int)offset, value);
if (offset >= SYBORG_VIRTIO_CONFIG) {
return virtio_config_writeb(vdev, offset - SYBORG_VIRTIO_CONFIG,
value);
}
BADF("Bad byte write offset 0x%x\n", (int)offset);
}
static CPUReadMemoryFunc * const syborg_virtio_readfn[] = {
syborg_virtio_readb,
syborg_virtio_readw,
syborg_virtio_readl
};
static CPUWriteMemoryFunc * const syborg_virtio_writefn[] = {
syborg_virtio_writeb,
syborg_virtio_writew,
syborg_virtio_writel
};
static void syborg_virtio_update_irq(void *opaque, uint16_t vector)
{
SyborgVirtIOProxy *proxy = opaque;
int level;
level = proxy->int_enable & proxy->vdev->isr;
DPRINTF("IRQ %d\n", level);
qemu_set_irq(proxy->irq, level != 0);
}
static unsigned syborg_virtio_get_features(void *opaque)
{
SyborgVirtIOProxy *proxy = opaque;
return proxy->host_features;
}
static VirtIOBindings syborg_virtio_bindings = {
.notify = syborg_virtio_update_irq,
.get_features = syborg_virtio_get_features,
};
static int syborg_virtio_init(SyborgVirtIOProxy *proxy, VirtIODevice *vdev)
{
int iomemtype;
proxy->vdev = vdev;
/* Don't support multiple vectors */
proxy->vdev->nvectors = 0;
sysbus_init_irq(&proxy->busdev, &proxy->irq);
iomemtype = cpu_register_io_memory(syborg_virtio_readfn,
syborg_virtio_writefn, proxy);
sysbus_init_mmio(&proxy->busdev, 0x1000, iomemtype);
proxy->id = ((uint32_t)0x1af4 << 16) | vdev->device_id;
qemu_register_reset(virtio_reset, vdev);
virtio_bind_device(vdev, &syborg_virtio_bindings, proxy);
proxy->host_features |= (0x1 << VIRTIO_F_NOTIFY_ON_EMPTY);
proxy->host_features = vdev->get_features(vdev, proxy->host_features);
return 0;
}
/* Device specific bindings. */
static int syborg_virtio_net_init(SysBusDevice *dev)
{
VirtIODevice *vdev;
SyborgVirtIOProxy *proxy = FROM_SYSBUS(SyborgVirtIOProxy, dev);
vdev = virtio_net_init(&dev->qdev, &proxy->nic, &proxy->net);
return syborg_virtio_init(proxy, vdev);
}
static SysBusDeviceInfo syborg_virtio_net_info = {
.init = syborg_virtio_net_init,
.qdev.name = "syborg,virtio-net",
.qdev.size = sizeof(SyborgVirtIOProxy),
.qdev.props = (Property[]) {
DEFINE_NIC_PROPERTIES(SyborgVirtIOProxy, nic),
DEFINE_VIRTIO_NET_FEATURES(SyborgVirtIOProxy, host_features),
DEFINE_PROP_UINT32("x-txtimer", SyborgVirtIOProxy,
net.txtimer, TX_TIMER_INTERVAL),
DEFINE_PROP_INT32("x-txburst", SyborgVirtIOProxy,
net.txburst, TX_BURST),
DEFINE_PROP_STRING("tx", SyborgVirtIOProxy, net.tx),
DEFINE_PROP_END_OF_LIST(),
}
};
static void syborg_virtio_register_devices(void)
{
sysbus_register_withprop(&syborg_virtio_net_info);
}
device_init(syborg_virtio_register_devices)
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