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Subject[RFC PATCH] vhost: Enable vhost-blk support
Date
From: Liu Yuan <tailai.ly@taobao.com>

vhost-blk is an in-kernel accelerator for virtio-blk
device. This patch is the counterpart of the vhost-blk
module in the kernel. It basically does setup of the
vhost-blk, pass on the virtio buffer information via
/dev/vhost-blk.

Useage:
$:qemu -drvie file=path/to/image,if=virtio,aio=native...

Signed-off-by: Liu Yuan <tailai.ly@taobao.com>
---
Makefile.target | 2 +-
hw/vhost_blk.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
hw/vhost_blk.h | 44 ++++++++++++++++++++++++++++
hw/virtio-blk.c | 74 ++++++++++++++++++++++++++++++++++++++----------
hw/virtio-blk.h | 15 ++++++++++
hw/virtio-pci.c | 12 ++++++-
6 files changed, 213 insertions(+), 18 deletions(-)
create mode 100644 hw/vhost_blk.c
create mode 100644 hw/vhost_blk.h
diff --git a/Makefile.target b/Makefile.target
index c511010..0f62d7e 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -198,7 +198,7 @@ obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o vl.o balloon.o
obj-$(CONFIG_NO_PCI) += pci-stub.o
obj-$(CONFIG_PCI) += pci.o
obj-$(CONFIG_VIRTIO) += virtio-blk.o virtio-balloon.o virtio-net.o virtio-serial-bus.o
-obj-y += vhost_net.o
+obj-y += vhost_net.o vhost_blk.o
obj-$(CONFIG_VHOST_NET) += vhost.o
obj-$(CONFIG_REALLY_VIRTFS) += 9pfs/virtio-9p-device.o
obj-y += rwhandler.o
diff --git a/hw/vhost_blk.c b/hw/vhost_blk.c
new file mode 100644
index 0000000..31fb11f
--- /dev/null
+++ b/hw/vhost_blk.c
@@ -0,0 +1,84 @@
+#if 1
+#include <linux/vhost.h>
+#include <linux/kvm.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/virtio_ring.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "vhost.h"
+#include "vhost_blk.h"
+
+struct vhost_blk * vhost_blk_init(void)
+{
+ struct vhost_blk *blk = qemu_mallocz(sizeof *blk);
+ int err;
+
+ err = open("/dev/vhost-blk", O_RDWR);
+ if (err < 0)
+ goto err_open;
+ blk->fd = err;
+ err = vhost_dev_init(&blk->dev, err, 1);
+ if (err < 0)
+ goto err_init;
+
+ blk->dev.vqs = blk->vqs;
+ blk->dev.nvqs = blk_vq_max;
+ return blk;
+err_init:
+ close(blk->fd);
+err_open:
+ perror("vhost_blk_init");
+ qemu_free(blk);
+ return NULL;
+}
+
+typedef struct BDRVRawState {
+ int fd;
+ int type;
+ int open_flags;
+#if defined(__linux__)
+ /* linux floppy specific */
+ int64_t fd_open_time;
+ int64_t fd_error_time;
+ int fd_got_error;
+ int fd_media_changed;
+#endif
+#ifdef CONFIG_LINUX_AIO
+ int use_aio;
+ void *aio_ctx;
+#endif
+ uint8_t *aligned_buf;
+ unsigned aligned_buf_size;
+#ifdef CONFIG_XFS
+ bool is_xfs : 1;
+#endif
+} BDRVRawState;
+
+int vhost_blk_start(struct vhost_blk *blk, VirtIODevice *device)
+{
+ VirtIOBlock *iob = (VirtIOBlock *)device;
+ BDRVRawState *raw = iob->bs->file->opaque;
+ struct vhost_vring_file f = {blk_vq_idx, raw->fd};
+ static int i = 0;
+ int ret;
+
+ ret = vhost_dev_start(&blk->dev, device);
+ if (ret < 0)
+ goto err_start;
+
+ ret = ioctl(blk->fd, VHOST_NET_SET_BACKEND, &f);
+ if (ret <0)
+ goto err_ioctl;
+
+ printf("%s: vhost-blk get started successfully (%d)\n", __func__, i++);
+ return ret;
+
+err_ioctl:
+ vhost_dev_stop(&blk->dev, device);
+err_start:
+ return ret;
+}
+#endif
diff --git a/hw/vhost_blk.h b/hw/vhost_blk.h
new file mode 100644
index 0000000..f437af5
--- /dev/null
+++ b/hw/vhost_blk.h
@@ -0,0 +1,44 @@
+#ifndef VHOST_BLK_H
+#define VHOST_BLK_H
+
+#include <errno.h>
+
+#include "virtio-blk.h"
+#include "vhost.h"
+
+enum {
+ blk_vq_idx = 0,
+ blk_vq_max = 1,
+};
+
+struct vhost_blk {
+ struct vhost_dev dev;
+ struct vhost_virtqueue vqs[blk_vq_max];
+ int fd;
+};
+
+# if 1
+extern struct vhost_blk * vhost_blk_init(void);
+extern int vhost_blk_start(struct vhost_blk *blk, VirtIODevice *device);
+static inline struct vhost_blk * to_vhost_blk(VirtIODevice *device)
+{
+ VirtIOBlock * iob = (VirtIOBlock *)device;
+ return iob->vblk;
+}
+# else
+static inline struct vhost_blk * vhost_blk_init(void);
+{
+ return NULL;
+}
+
+static inline int vhost_blk_start(struct vhost_blk *vblk, VirtIODevice *device)
+{
+ return -1;
+}
+
+static inline struct vhost_blk * to_vhost_blk(VirtIODevice *device)
+{
+ return NULL;
+}
+#endif
+#endif /* VHOST_BLK_H */
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 6471ac8..a5f3a27 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -16,23 +16,32 @@
#include "trace.h"
#include "blockdev.h"
#include "virtio-blk.h"
+#include "vhost_blk.h"
#ifdef __linux__
# include <scsi/sg.h>
#endif

-typedef struct VirtIOBlock
-{
- VirtIODevice vdev;
- BlockDriverState *bs;
- VirtQueue *vq;
- void *rq;
- QEMUBH *bh;
- BlockConf *conf;
- char *serial;
- unsigned short sector_mask;
- DeviceState *qdev;
-} VirtIOBlock;
-
+typedef struct BDRVRawState {
+ int fd;
+ int type;
+ int open_flags;
+#if defined(__linux__)
+ /* linux floppy specific */
+ int64_t fd_open_time;
+ int64_t fd_error_time;
+ int fd_got_error;
+ int fd_media_changed;
+#endif
+#ifdef CONFIG_LINUX_AIO
+ int use_aio;
+ void *aio_ctx;
+#endif
+ uint8_t *aligned_buf;
+ unsigned aligned_buf_size;
+#ifdef CONFIG_XFS
+ bool is_xfs : 1;
+#endif
+} BDRVRawState;
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
{
return (VirtIOBlock *)vdev;
@@ -436,6 +445,29 @@ static void virtio_blk_dma_restart_cb(void *opaque, int running, int reason)
}
}

+#include <sys/ioctl.h>
+#include <linux/vhost.h>
+static void vhost_blk_reset(VirtIODevice *device)
+{
+ //int err;
+ struct vhost_blk *vblk = to_vhost_blk(device);
+
+ if (!vblk)
+ return;
+
+ if (!vblk->dev.started)
+ return;
+
+ vhost_dev_stop(&vblk->dev, device);
+ if (!ioctl(vblk->fd, VHOST_RESET_OWNER, NULL) &&
+ !ioctl(vblk->fd, VHOST_SET_OWNER, NULL))
+ vblk->dev.acked_features = 0;
+ else
+ printf("%s %d fd %d\n", __func__, -errno, vblk->fd);
+
+ return;
+}
+
static void virtio_blk_reset(VirtIODevice *vdev)
{
/*
@@ -443,6 +475,7 @@ static void virtio_blk_reset(VirtIODevice *vdev)
* are per-device request lists.
*/
qemu_aio_flush();
+ vhost_blk_reset(vdev);
}

/* coalesce internal state, copy to pci i/o region 0
@@ -482,20 +515,29 @@ static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features)

if (bdrv_enable_write_cache(s->bs))
features |= (1 << VIRTIO_BLK_F_WCACHE);
-
+
if (bdrv_is_read_only(s->bs))
features |= 1 << VIRTIO_BLK_F_RO;

return features;
}

+static void virtio_blk_set_features(VirtIODevice *vdev, uint32_t val)
+{
+ VirtIOBlock *s = to_virtio_blk(vdev);
+ if (s->vblk) {
+ val &= ~(1 << VIRTIO_BLK_F_WCACHE);
+ s->vblk->dev.acked_features = val;
+ }
+}
+
static void virtio_blk_save(QEMUFile *f, void *opaque)
{
VirtIOBlock *s = opaque;
VirtIOBlockReq *req = s->rq;

virtio_save(&s->vdev, f);
-
+
while (req) {
qemu_put_sbyte(f, 1);
qemu_put_buffer(f, (unsigned char*)&req->elem, sizeof(req->elem));
@@ -567,6 +609,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf,

s->vdev.get_config = virtio_blk_update_config;
s->vdev.get_features = virtio_blk_get_features;
+ s->vdev.set_features = virtio_blk_set_features;
s->vdev.reset = virtio_blk_reset;
s->bs = conf->bs;
s->conf = conf;
@@ -587,6 +630,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, BlockConf *conf,

add_boot_device_path(conf->bootindex, dev, "/disk@0,0");

+ s->vblk = vhost_blk_init();
return &s->vdev;
}

diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
index 5645d2b..cdaa0ef 100644
--- a/hw/virtio-blk.h
+++ b/hw/virtio-blk.h
@@ -16,6 +16,7 @@

#include "virtio.h"
#include "block.h"
+#include "blockdev.h"

/* from Linux's linux/virtio_blk.h */

@@ -97,6 +98,20 @@ struct virtio_scsi_inhdr
uint32_t residual;
};

+typedef struct VirtIOBlock
+{
+ VirtIODevice vdev;
+ BlockDriverState *bs;
+ VirtQueue *vq;
+ void *rq;
+ QEMUBH *bh;
+ BlockConf *conf;
+ char *serial;
+ unsigned short sector_mask;
+ DeviceState *qdev;
+ struct vhost_blk *vblk;
+} VirtIOBlock;
+
#ifdef __linux__
#define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \
DEFINE_VIRTIO_COMMON_FEATURES(_state, _field), \
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index c5bfb62..f653014 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -27,6 +27,8 @@
#include "kvm.h"
#include "blockdev.h"
#include "virtio-pci.h"
+#include "vhost_blk.h"
+#include "vhost.h"

/* from Linux's linux/virtio_pci.h */

@@ -162,6 +164,7 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
VirtQueue *vq = virtio_get_queue(proxy->vdev, n);
EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
int r;
+
if (assign) {
r = event_notifier_init(notifier, 1);
if (r < 0) {
@@ -190,7 +193,7 @@ static int virtio_pci_set_host_notifier_internal(VirtIOPCIProxy *proxy,
/* Handle the race condition where the guest kicked and we deassigned
* before we got around to handling the kick.
*/
- if (event_notifier_test_and_clear(notifier)) {
+ if (proxy->ioeventfd_started && event_notifier_test_and_clear(notifier)) {
virtio_queue_notify_vq(vq);
}

@@ -337,7 +340,12 @@ static void virtio_ioport_write(void *opaque, uint32_t addr, uint32_t val)
virtio_set_status(vdev, val & 0xFF);

if (val & VIRTIO_CONFIG_S_DRIVER_OK) {
- virtio_pci_start_ioeventfd(proxy);
+ struct vhost_blk *vblk = to_vhost_blk(vdev);
+ if (vblk) {
+ if (!vblk->dev.started)
+ vhost_blk_start(to_vhost_blk(vdev), vdev);
+ } else
+ virtio_pci_start_ioeventfd(proxy);
}

if (vdev->status == 0) {
--
1.7.5.1


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