Patchwork [PATCHv6,08/11] vhost: vhost net support

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Submitter Michael S. Tsirkin
Date March 17, 2010, 11:08 a.m.
Message ID <057ffaff8c6520537b8f0cc0647bb291862d3456.1268823114.git.mst@redhat.com>
Download mbox | patch
Permalink /patch/47939/
State New
Headers show

Comments

Michael S. Tsirkin - March 17, 2010, 11:08 a.m.
This adds vhost net device support in qemu. Will be tied to tap device
and virtio by following patches.  Raw backend is currently missing,
will be worked on/submitted separately.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 Makefile.target |    2 +
 configure       |   37 +++
 hw/vhost.c      |  711 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 hw/vhost.h      |   48 ++++
 hw/vhost_net.c  |  195 +++++++++++++++
 hw/vhost_net.h  |   19 ++
 6 files changed, 1012 insertions(+), 0 deletions(-)
 create mode 100644 hw/vhost.c
 create mode 100644 hw/vhost.h
 create mode 100644 hw/vhost_net.c
 create mode 100644 hw/vhost_net.h
Anthony Liguori - March 22, 2010, 8:58 p.m.
On 03/17/2010 06:08 AM, Michael S. Tsirkin wrote:
> This adds vhost net device support in qemu. Will be tied to tap device
> and virtio by following patches.  Raw backend is currently missing,
> will be worked on/submitted separately.
>
> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
> ---
>   Makefile.target |    2 +
>   configure       |   37 +++
>   hw/vhost.c      |  711 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>   hw/vhost.h      |   48 ++++
>   hw/vhost_net.c  |  195 +++++++++++++++
>   hw/vhost_net.h  |   19 ++
>   6 files changed, 1012 insertions(+), 0 deletions(-)
>   create mode 100644 hw/vhost.c
>   create mode 100644 hw/vhost.h
>   create mode 100644 hw/vhost_net.c
>   create mode 100644 hw/vhost_net.h
>
> diff --git a/Makefile.target b/Makefile.target
> index 004a703..ea5207c 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -176,6 +176,8 @@ obj-y = vl.o async.o monitor.o pci.o pci_host.o pcie_host.o machine.o gdbstub.o
>   # need to fix this properly
>   obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o virtio-serial-bus.o
>   obj-y += event_notifier.o
> +obj-y += vhost_net.o
> +obj-$(CONFIG_VHOST_NET) += vhost.o
>   obj-y += rwhandler.o
>   obj-$(CONFIG_KVM) += kvm.o kvm-all.o
>   obj-$(CONFIG_ISA_MMIO) += isa_mmio.o
> diff --git a/configure b/configure
> index d728799..93015e3 100755
> --- a/configure
> +++ b/configure
> @@ -263,6 +263,7 @@ vnc_tls=""
>   vnc_sasl=""
>   xen=""
>   linux_aio=""
> +vhost_net=""
>
>   gprof="no"
>   debug_tcg="no"
> @@ -651,6 +652,10 @@ for opt do
>     ;;
>     --enable-docs) docs="yes"
>     ;;
> +  --disable-vhost-net) vhost_net="no"
> +  ;;
> +  --enable-vhost-net) vhost_net="yes"
> +  ;;
>     *) echo "ERROR: unknown option $opt"; show_help="yes"
>     ;;
>     esac
> @@ -806,6 +811,8 @@ echo "  --disable-blobs          disable installing provided firmware blobs"
>   echo "  --kerneldir=PATH         look for kernel includes in PATH"
>   echo "  --enable-docs            enable documentation build"
>   echo "  --disable-docs           disable documentation build"
> +echo "  --disable-vhost-net      disable vhost-net acceleration support"
> +echo "  --enable-vhost-net       enable vhost-net acceleration support"
>   echo ""
>   echo "NOTE: The object files are built at the place where configure is launched"
>   exit 1
> @@ -1498,6 +1505,32 @@ EOF
>   fi
>
>   ##########################################
> +# test for vhost net
> +
> +if test "$vhost_net" != "no"; then
> +    if test "$kvm" != "no"; then
> +            cat>  $TMPC<<EOF
> +    #include<linux/vhost.h>
> +    int main(void) { return 0; }
> +EOF
> +            if compile_prog "$kvm_cflags" "" ; then
> +                vhost_net=yes
> +            else
> +                if "$vhost_net" == "yes" ; then
> +                    feature_not_found "vhost-net"
> +                fi
> +                vhost_net=no
> +            fi
> +    else
> +            if "$vhost_net" == "yes" ; then
> +                echo -e "NOTE: vhost-net feature requires KVM (--enable-kvm)."
> +                feature_not_found "vhost-net"
> +            fi
>    

The indent is quite a bit off here but more importantly, if "$vhost_net" 
== "yes" is not a valid shell command.  Instead, it ought to be:

if test "$vhost_net" = "yes" ; then

And likewise for the earlier check.  I'll fold this fix into your series 
unless you'd like to respin for some reason.

Regards,

Anthony Liguori+ cpu_physical_memory_set_dirty(addr + bit * VHOST_LOG_PAGE);
Michael S. Tsirkin - March 22, 2010, 9:11 p.m.
On Mon, Mar 22, 2010 at 03:58:58PM -0500, Anthony Liguori wrote:
> On 03/17/2010 06:08 AM, Michael S. Tsirkin wrote:
>> This adds vhost net device support in qemu. Will be tied to tap device
>> and virtio by following patches.  Raw backend is currently missing,
>> will be worked on/submitted separately.
>>
>> Signed-off-by: Michael S. Tsirkin<mst@redhat.com>
>> ---
>>   Makefile.target |    2 +
>>   configure       |   37 +++
>>   hw/vhost.c      |  711 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>   hw/vhost.h      |   48 ++++
>>   hw/vhost_net.c  |  195 +++++++++++++++
>>   hw/vhost_net.h  |   19 ++
>>   6 files changed, 1012 insertions(+), 0 deletions(-)
>>   create mode 100644 hw/vhost.c
>>   create mode 100644 hw/vhost.h
>>   create mode 100644 hw/vhost_net.c
>>   create mode 100644 hw/vhost_net.h
>>
>> diff --git a/Makefile.target b/Makefile.target
>> index 004a703..ea5207c 100644
>> --- a/Makefile.target
>> +++ b/Makefile.target
>> @@ -176,6 +176,8 @@ obj-y = vl.o async.o monitor.o pci.o pci_host.o pcie_host.o machine.o gdbstub.o
>>   # need to fix this properly
>>   obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o virtio-serial-bus.o
>>   obj-y += event_notifier.o
>> +obj-y += vhost_net.o
>> +obj-$(CONFIG_VHOST_NET) += vhost.o
>>   obj-y += rwhandler.o
>>   obj-$(CONFIG_KVM) += kvm.o kvm-all.o
>>   obj-$(CONFIG_ISA_MMIO) += isa_mmio.o
>> diff --git a/configure b/configure
>> index d728799..93015e3 100755
>> --- a/configure
>> +++ b/configure
>> @@ -263,6 +263,7 @@ vnc_tls=""
>>   vnc_sasl=""
>>   xen=""
>>   linux_aio=""
>> +vhost_net=""
>>
>>   gprof="no"
>>   debug_tcg="no"
>> @@ -651,6 +652,10 @@ for opt do
>>     ;;
>>     --enable-docs) docs="yes"
>>     ;;
>> +  --disable-vhost-net) vhost_net="no"
>> +  ;;
>> +  --enable-vhost-net) vhost_net="yes"
>> +  ;;
>>     *) echo "ERROR: unknown option $opt"; show_help="yes"
>>     ;;
>>     esac
>> @@ -806,6 +811,8 @@ echo "  --disable-blobs          disable installing provided firmware blobs"
>>   echo "  --kerneldir=PATH         look for kernel includes in PATH"
>>   echo "  --enable-docs            enable documentation build"
>>   echo "  --disable-docs           disable documentation build"
>> +echo "  --disable-vhost-net      disable vhost-net acceleration support"
>> +echo "  --enable-vhost-net       enable vhost-net acceleration support"
>>   echo ""
>>   echo "NOTE: The object files are built at the place where configure is launched"
>>   exit 1
>> @@ -1498,6 +1505,32 @@ EOF
>>   fi
>>
>>   ##########################################
>> +# test for vhost net
>> +
>> +if test "$vhost_net" != "no"; then
>> +    if test "$kvm" != "no"; then
>> +            cat>  $TMPC<<EOF
>> +    #include<linux/vhost.h>
>> +    int main(void) { return 0; }
>> +EOF
>> +            if compile_prog "$kvm_cflags" "" ; then
>> +                vhost_net=yes
>> +            else
>> +                if "$vhost_net" == "yes" ; then
>> +                    feature_not_found "vhost-net"
>> +                fi
>> +                vhost_net=no
>> +            fi
>> +    else
>> +            if "$vhost_net" == "yes" ; then
>> +                echo -e "NOTE: vhost-net feature requires KVM (--enable-kvm)."
>> +                feature_not_found "vhost-net"
>> +            fi
>>    
>
> The indent is quite a bit off here but more importantly, if "$vhost_net"  
> == "yes" is not a valid shell command.  Instead, it ought to be:
>
> if test "$vhost_net" = "yes" ; then
>
> And likewise for the earlier check.  I'll fold this fix into your series  
> unless you'd like to respin for some reason.

So you fixed this yourself? Sure, thanks a lot!

> Regards,
>
> Anthony Liguori+ cpu_physical_memory_set_dirty(addr + bit * VHOST_LOG_PAGE);

Cool new sig.

Patch

diff --git a/Makefile.target b/Makefile.target
index 004a703..ea5207c 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -176,6 +176,8 @@  obj-y = vl.o async.o monitor.o pci.o pci_host.o pcie_host.o machine.o gdbstub.o
 # need to fix this properly
 obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o virtio-serial-bus.o
 obj-y += event_notifier.o
+obj-y += vhost_net.o
+obj-$(CONFIG_VHOST_NET) += vhost.o
 obj-y += rwhandler.o
 obj-$(CONFIG_KVM) += kvm.o kvm-all.o
 obj-$(CONFIG_ISA_MMIO) += isa_mmio.o
diff --git a/configure b/configure
index d728799..93015e3 100755
--- a/configure
+++ b/configure
@@ -263,6 +263,7 @@  vnc_tls=""
 vnc_sasl=""
 xen=""
 linux_aio=""
+vhost_net=""
 
 gprof="no"
 debug_tcg="no"
@@ -651,6 +652,10 @@  for opt do
   ;;
   --enable-docs) docs="yes"
   ;;
+  --disable-vhost-net) vhost_net="no"
+  ;;
+  --enable-vhost-net) vhost_net="yes"
+  ;;
   *) echo "ERROR: unknown option $opt"; show_help="yes"
   ;;
   esac
@@ -806,6 +811,8 @@  echo "  --disable-blobs          disable installing provided firmware blobs"
 echo "  --kerneldir=PATH         look for kernel includes in PATH"
 echo "  --enable-docs            enable documentation build"
 echo "  --disable-docs           disable documentation build"
+echo "  --disable-vhost-net      disable vhost-net acceleration support"
+echo "  --enable-vhost-net       enable vhost-net acceleration support"
 echo ""
 echo "NOTE: The object files are built at the place where configure is launched"
 exit 1
@@ -1498,6 +1505,32 @@  EOF
 fi
 
 ##########################################
+# test for vhost net
+
+if test "$vhost_net" != "no"; then
+    if test "$kvm" != "no"; then
+            cat > $TMPC <<EOF
+    #include <linux/vhost.h>
+    int main(void) { return 0; }
+EOF
+            if compile_prog "$kvm_cflags" "" ; then
+                vhost_net=yes
+            else
+                if "$vhost_net" == "yes" ; then
+                    feature_not_found "vhost-net"
+                fi
+                vhost_net=no
+            fi
+    else
+            if "$vhost_net" == "yes" ; then
+                echo -e "NOTE: vhost-net feature requires KVM (--enable-kvm)."
+                feature_not_found "vhost-net"
+            fi
+            vhost_net=no
+    fi
+fi
+
+##########################################
 # pthread probe
 PTHREADLIBS_LIST="-lpthread -lpthreadGC2"
 
@@ -1968,6 +2001,7 @@  echo "fdt support       $fdt"
 echo "preadv support    $preadv"
 echo "fdatasync         $fdatasync"
 echo "uuid support      $uuid"
+echo "vhost-net support $vhost_net"
 
 if test $sdl_too_old = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -2492,6 +2526,9 @@  case "$target_arch2" in
       if test "$kvm_para" = "yes"; then
         echo "CONFIG_KVM_PARA=y" >> $config_target_mak
       fi
+      if test $vhost_net = "yes" ; then
+        echo "CONFIG_VHOST_NET=y" >> $config_target_mak
+      fi
     fi
 esac
 if test "$target_bigendian" = "yes" ; then
diff --git a/hw/vhost.c b/hw/vhost.c
new file mode 100644
index 0000000..1e5bc69
--- /dev/null
+++ b/hw/vhost.c
@@ -0,0 +1,711 @@ 
+/*
+ * vhost support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include <linux/vhost.h>
+#include <sys/ioctl.h>
+#include <sys/eventfd.h>
+#include "vhost.h"
+#include "hw/hw.h"
+/* For range_get_last */
+#include "pci.h"
+
+static void vhost_dev_sync_region(struct vhost_dev *dev,
+                                  uint64_t mfirst, uint64_t mlast,
+                                  uint64_t rfirst, uint64_t rlast)
+{
+    uint64_t start = MAX(mfirst, rfirst);
+    uint64_t end = MIN(mlast, rlast);
+    vhost_log_chunk_t *from = dev->log + start / VHOST_LOG_CHUNK;
+    vhost_log_chunk_t *to = dev->log + end / VHOST_LOG_CHUNK + 1;
+    uint64_t addr = (start / VHOST_LOG_CHUNK) * VHOST_LOG_CHUNK;
+
+    assert(end / VHOST_LOG_CHUNK < dev->log_size);
+    assert(start / VHOST_LOG_CHUNK < dev->log_size);
+    if (end < start) {
+        return;
+    }
+    for (;from < to; ++from) {
+        vhost_log_chunk_t log;
+        int bit;
+        /* We first check with non-atomic: much cheaper,
+         * and we expect non-dirty to be the common case. */
+        if (!*from) {
+            continue;
+        }
+        /* Data must be read atomically. We don't really
+         * need the barrier semantics of __sync
+         * builtins, but it's easier to use them than
+         * roll our own. */
+        log = __sync_fetch_and_and(from, 0);
+        while ((bit = sizeof(log) > sizeof(int) ?
+                ffsll(log) : ffs(log))) {
+            bit -= 1;
+            cpu_physical_memory_set_dirty(addr + bit * VHOST_LOG_PAGE);
+            log &= ~(0x1ull << bit);
+        }
+        addr += VHOST_LOG_CHUNK;
+    }
+}
+
+static int vhost_client_sync_dirty_bitmap(CPUPhysMemoryClient *client,
+                                          target_phys_addr_t start_addr,
+                                          target_phys_addr_t end_addr)
+{
+    struct vhost_dev *dev = container_of(client, struct vhost_dev, client);
+    int i;
+    if (!dev->log_enabled || !dev->started) {
+        return 0;
+    }
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        vhost_dev_sync_region(dev, start_addr, end_addr,
+                              reg->guest_phys_addr,
+                              range_get_last(reg->guest_phys_addr,
+                                             reg->memory_size));
+    }
+    for (i = 0; i < dev->nvqs; ++i) {
+        struct vhost_virtqueue *vq = dev->vqs + i;
+        vhost_dev_sync_region(dev, start_addr, end_addr, vq->used_phys,
+                              range_get_last(vq->used_phys, vq->used_size));
+    }
+    return 0;
+}
+
+/* Assign/unassign. Keep an unsorted array of non-overlapping
+ * memory regions in dev->mem. */
+static void vhost_dev_unassign_memory(struct vhost_dev *dev,
+                                      uint64_t start_addr,
+                                      uint64_t size)
+{
+    int from, to, n = dev->mem->nregions;
+    /* Track overlapping/split regions for sanity checking. */
+    int overlap_start = 0, overlap_end = 0, overlap_middle = 0, split = 0;
+
+    for (from = 0, to = 0; from < n; ++from, ++to) {
+        struct vhost_memory_region *reg = dev->mem->regions + to;
+        uint64_t reglast;
+        uint64_t memlast;
+        uint64_t change;
+
+        /* clone old region */
+        if (to != from) {
+            memcpy(reg, dev->mem->regions + from, sizeof *reg);
+        }
+
+        /* No overlap is simple */
+        if (!ranges_overlap(reg->guest_phys_addr, reg->memory_size,
+                            start_addr, size)) {
+            continue;
+        }
+
+        /* Split only happens if supplied region
+         * is in the middle of an existing one. Thus it can not
+         * overlap with any other existing region. */
+        assert(!split);
+
+        reglast = range_get_last(reg->guest_phys_addr, reg->memory_size);
+        memlast = range_get_last(start_addr, size);
+
+        /* Remove whole region */
+        if (start_addr <= reg->guest_phys_addr && memlast >= reglast) {
+            --dev->mem->nregions;
+            --to;
+            assert(to >= 0);
+            ++overlap_middle;
+            continue;
+        }
+
+        /* Shrink region */
+        if (memlast >= reglast) {
+            reg->memory_size = start_addr - reg->guest_phys_addr;
+            assert(reg->memory_size);
+            assert(!overlap_end);
+            ++overlap_end;
+            continue;
+        }
+
+        /* Shift region */
+        if (start_addr <= reg->guest_phys_addr) {
+            change = memlast + 1 - reg->guest_phys_addr;
+            reg->memory_size -= change;
+            reg->guest_phys_addr += change;
+            reg->userspace_addr += change;
+            assert(reg->memory_size);
+            assert(!overlap_start);
+            ++overlap_start;
+            continue;
+        }
+
+        /* This only happens if supplied region
+         * is in the middle of an existing one. Thus it can not
+         * overlap with any other existing region. */
+        assert(!overlap_start);
+        assert(!overlap_end);
+        assert(!overlap_middle);
+        /* Split region: shrink first part, shift second part. */
+        memcpy(dev->mem->regions + n, reg, sizeof *reg);
+        reg->memory_size = start_addr - reg->guest_phys_addr;
+        assert(reg->memory_size);
+        change = memlast + 1 - reg->guest_phys_addr;
+        reg = dev->mem->regions + n;
+        reg->memory_size -= change;
+        assert(reg->memory_size);
+        reg->guest_phys_addr += change;
+        reg->userspace_addr += change;
+        /* Never add more than 1 region */
+        assert(dev->mem->nregions == n);
+        ++dev->mem->nregions;
+        ++split;
+    }
+}
+
+/* Called after unassign, so no regions overlap the given range. */
+static void vhost_dev_assign_memory(struct vhost_dev *dev,
+                                    uint64_t start_addr,
+                                    uint64_t size,
+                                    uint64_t uaddr)
+{
+    int from, to;
+    struct vhost_memory_region *merged = NULL;
+    for (from = 0, to = 0; from < dev->mem->nregions; ++from, ++to) {
+        struct vhost_memory_region *reg = dev->mem->regions + to;
+        uint64_t prlast, urlast;
+        uint64_t pmlast, umlast;
+        uint64_t s, e, u;
+
+        /* clone old region */
+        if (to != from) {
+            memcpy(reg, dev->mem->regions + from, sizeof *reg);
+        }
+        prlast = range_get_last(reg->guest_phys_addr, reg->memory_size);
+        pmlast = range_get_last(start_addr, size);
+        urlast = range_get_last(reg->userspace_addr, reg->memory_size);
+        umlast = range_get_last(uaddr, size);
+
+        /* check for overlapping regions: should never happen. */
+        assert(prlast < start_addr || pmlast < reg->guest_phys_addr);
+        /* Not an adjacent or overlapping region - do not merge. */
+        if ((prlast + 1 != start_addr || urlast + 1 != uaddr) &&
+            (pmlast + 1 != reg->guest_phys_addr ||
+             umlast + 1 != reg->userspace_addr)) {
+            continue;
+        }
+
+        if (merged) {
+            --to;
+            assert(to >= 0);
+        } else {
+            merged = reg;
+        }
+        u = MIN(uaddr, reg->userspace_addr);
+        s = MIN(start_addr, reg->guest_phys_addr);
+        e = MAX(pmlast, prlast);
+        uaddr = merged->userspace_addr = u;
+        start_addr = merged->guest_phys_addr = s;
+        size = merged->memory_size = e - s + 1;
+        assert(merged->memory_size);
+    }
+
+    if (!merged) {
+        struct vhost_memory_region *reg = dev->mem->regions + to;
+        memset(reg, 0, sizeof *reg);
+        reg->memory_size = size;
+        assert(reg->memory_size);
+        reg->guest_phys_addr = start_addr;
+        reg->userspace_addr = uaddr;
+        ++to;
+    }
+    assert(to <= dev->mem->nregions + 1);
+    dev->mem->nregions = to;
+}
+
+static uint64_t vhost_get_log_size(struct vhost_dev *dev)
+{
+    uint64_t log_size = 0;
+    int i;
+    for (i = 0; i < dev->mem->nregions; ++i) {
+        struct vhost_memory_region *reg = dev->mem->regions + i;
+        uint64_t last = range_get_last(reg->guest_phys_addr,
+                                       reg->memory_size);
+        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);
+    }
+    for (i = 0; i < dev->nvqs; ++i) {
+        struct vhost_virtqueue *vq = dev->vqs + i;
+        uint64_t last = vq->used_phys + vq->used_size - 1;
+        log_size = MAX(log_size, last / VHOST_LOG_CHUNK + 1);
+    }
+    return log_size;
+}
+
+static inline void vhost_dev_log_resize(struct vhost_dev* dev, uint64_t size)
+{
+    vhost_log_chunk_t *log;
+    uint64_t log_base;
+    int r;
+    if (size) {
+        log = qemu_mallocz(size * sizeof *log);
+    } else {
+        log = NULL;
+    }
+    log_base = (uint64_t)(unsigned long)log;
+    r = ioctl(dev->control, VHOST_SET_LOG_BASE, &log_base);
+    assert(r >= 0);
+    vhost_client_sync_dirty_bitmap(&dev->client, 0,
+                                   (target_phys_addr_t)~0x0ull);
+    if (dev->log) {
+        qemu_free(dev->log);
+    }
+    dev->log = log;
+    dev->log_size = size;
+}
+
+static int vhost_verify_ring_mappings(struct vhost_dev *dev,
+                                      uint64_t start_addr,
+                                      uint64_t size)
+{
+    int i;
+    for (i = 0; i < dev->nvqs; ++i) {
+        struct vhost_virtqueue *vq = dev->vqs + i;
+        target_phys_addr_t l;
+        void *p;
+
+        if (!ranges_overlap(start_addr, size, vq->ring_phys, vq->ring_size)) {
+            continue;
+        }
+        l = vq->ring_size;
+        p = cpu_physical_memory_map(vq->ring_phys, &l, 1);
+        if (!p || l != vq->ring_size) {
+            fprintf(stderr, "Unable to map ring buffer for ring %d\n", i);
+            return -ENOMEM;
+        }
+        if (p != vq->ring) {
+            fprintf(stderr, "Ring buffer relocated for ring %d\n", i);
+            return -EBUSY;
+        }
+        cpu_physical_memory_unmap(p, l, 0, 0);
+    }
+    return 0;
+}
+
+static void vhost_client_set_memory(CPUPhysMemoryClient *client,
+                                    target_phys_addr_t start_addr,
+                                    ram_addr_t size,
+                                    ram_addr_t phys_offset)
+{
+    struct vhost_dev *dev = container_of(client, struct vhost_dev, client);
+    ram_addr_t flags = phys_offset & ~TARGET_PAGE_MASK;
+    int s = offsetof(struct vhost_memory, regions) +
+        (dev->mem->nregions + 1) * sizeof dev->mem->regions[0];
+    uint64_t log_size;
+    int r;
+    dev->mem = qemu_realloc(dev->mem, s);
+
+    assert(size);
+
+    vhost_dev_unassign_memory(dev, start_addr, size);
+    if (flags == IO_MEM_RAM) {
+        /* Add given mapping, merging adjacent regions if any */
+        vhost_dev_assign_memory(dev, start_addr, size,
+                                (uintptr_t)qemu_get_ram_ptr(phys_offset));
+    } else {
+        /* Remove old mapping for this memory, if any. */
+        vhost_dev_unassign_memory(dev, start_addr, size);
+    }
+
+    if (!dev->started) {
+        return;
+    }
+
+    if (dev->started) {
+        r = vhost_verify_ring_mappings(dev, start_addr, size);
+        assert(r >= 0);
+    }
+
+    if (!dev->log_enabled) {
+        r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
+        assert(r >= 0);
+        return;
+    }
+    log_size = vhost_get_log_size(dev);
+    /* We allocate an extra 4K bytes to log,
+     * to reduce the * number of reallocations. */
+#define VHOST_LOG_BUFFER (0x1000 / sizeof *dev->log)
+    /* To log more, must increase log size before table update. */
+    if (dev->log_size < log_size) {
+        vhost_dev_log_resize(dev, log_size + VHOST_LOG_BUFFER);
+    }
+    r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
+    assert(r >= 0);
+    /* To log less, can only decrease log size after table update. */
+    if (dev->log_size > log_size + VHOST_LOG_BUFFER) {
+        vhost_dev_log_resize(dev, log_size);
+    }
+}
+
+static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
+                                    struct vhost_virtqueue *vq,
+                                    unsigned idx, bool enable_log)
+{
+    struct vhost_vring_addr addr = {
+        .index = idx,
+        .desc_user_addr = (u_int64_t)(unsigned long)vq->desc,
+        .avail_user_addr = (u_int64_t)(unsigned long)vq->avail,
+        .used_user_addr = (u_int64_t)(unsigned long)vq->used,
+        .log_guest_addr = vq->used_phys,
+        .flags = enable_log ? (1 << VHOST_VRING_F_LOG) : 0,
+    };
+    int r = ioctl(dev->control, VHOST_SET_VRING_ADDR, &addr);
+    if (r < 0) {
+        return -errno;
+    }
+    return 0;
+}
+
+static int vhost_dev_set_features(struct vhost_dev *dev, bool enable_log)
+{
+    uint64_t features = dev->acked_features;
+    int r;
+    if (enable_log) {
+        features |= 0x1 << VHOST_F_LOG_ALL;
+    }
+    r = ioctl(dev->control, VHOST_SET_FEATURES, &features);
+    return r < 0 ? -errno : 0;
+}
+
+static int vhost_dev_set_log(struct vhost_dev *dev, bool enable_log)
+{
+    int r, t, i;
+    r = vhost_dev_set_features(dev, enable_log);
+    if (r < 0) {
+        goto err_features;
+    }
+    for (i = 0; i < dev->nvqs; ++i) {
+        r = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,
+                                     enable_log);
+        if (r < 0) {
+            goto err_vq;
+        }
+    }
+    return 0;
+err_vq:
+    for (; i >= 0; --i) {
+        t = vhost_virtqueue_set_addr(dev, dev->vqs + i, i,
+                                     dev->log_enabled);
+        assert(t >= 0);
+    }
+    t = vhost_dev_set_features(dev, dev->log_enabled);
+    assert(t >= 0);
+err_features:
+    return r;
+}
+
+static int vhost_client_migration_log(CPUPhysMemoryClient *client,
+                                      int enable)
+{
+    struct vhost_dev *dev = container_of(client, struct vhost_dev, client);
+    int r;
+    if (!!enable == dev->log_enabled) {
+        return 0;
+    }
+    if (!dev->started) {
+        dev->log_enabled = enable;
+        return 0;
+    }
+    if (!enable) {
+        r = vhost_dev_set_log(dev, false);
+        if (r < 0) {
+            return r;
+        }
+        if (dev->log) {
+            qemu_free(dev->log);
+        }
+        dev->log = NULL;
+        dev->log_size = 0;
+    } else {
+        vhost_dev_log_resize(dev, vhost_get_log_size(dev));
+        r = vhost_dev_set_log(dev, true);
+        if (r < 0) {
+            return r;
+        }
+    }
+    dev->log_enabled = enable;
+    return 0;
+}
+
+static int vhost_virtqueue_init(struct vhost_dev *dev,
+                                struct VirtIODevice *vdev,
+                                struct vhost_virtqueue *vq,
+                                unsigned idx)
+{
+    target_phys_addr_t s, l, a;
+    int r;
+    struct vhost_vring_file file = {
+        .index = idx,
+    };
+    struct vhost_vring_state state = {
+        .index = idx,
+    };
+    struct VirtQueue *vvq = virtio_get_queue(vdev, idx);
+
+    if (!vdev->binding->set_guest_notifier) {
+        fprintf(stderr, "binding does not support guest notifiers\n");
+        return -ENOSYS;
+    }
+
+    if (!vdev->binding->set_host_notifier) {
+        fprintf(stderr, "binding does not support host notifiers\n");
+        return -ENOSYS;
+    }
+
+    vq->num = state.num = virtio_queue_get_num(vdev, idx);
+    r = ioctl(dev->control, VHOST_SET_VRING_NUM, &state);
+    if (r) {
+        return -errno;
+    }
+
+    state.num = virtio_queue_get_last_avail_idx(vdev, idx);
+    r = ioctl(dev->control, VHOST_SET_VRING_BASE, &state);
+    if (r) {
+        return -errno;
+    }
+
+    s = l = virtio_queue_get_desc_size(vdev, idx);
+    a = virtio_queue_get_desc_addr(vdev, idx);
+    vq->desc = cpu_physical_memory_map(a, &l, 0);
+    if (!vq->desc || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_desc;
+    }
+    s = l = virtio_queue_get_avail_size(vdev, idx);
+    a = virtio_queue_get_avail_addr(vdev, idx);
+    vq->avail = cpu_physical_memory_map(a, &l, 0);
+    if (!vq->avail || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_avail;
+    }
+    vq->used_size = s = l = virtio_queue_get_used_size(vdev, idx);
+    vq->used_phys = a = virtio_queue_get_used_addr(vdev, idx);
+    vq->used = cpu_physical_memory_map(a, &l, 1);
+    if (!vq->used || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_used;
+    }
+
+    vq->ring_size = s = l = virtio_queue_get_ring_size(vdev, idx);
+    vq->ring_phys = a = virtio_queue_get_ring_addr(vdev, idx);
+    vq->ring = cpu_physical_memory_map(a, &l, 1);
+    if (!vq->ring || l != s) {
+        r = -ENOMEM;
+        goto fail_alloc_ring;
+    }
+
+    r = vhost_virtqueue_set_addr(dev, vq, idx, dev->log_enabled);
+    if (r < 0) {
+        r = -errno;
+        goto fail_alloc;
+    }
+    r = vdev->binding->set_guest_notifier(vdev->binding_opaque, idx, true);
+    if (r < 0) {
+        fprintf(stderr, "Error binding guest notifier: %d\n", -r);
+        goto fail_guest_notifier;
+    }
+
+    r = vdev->binding->set_host_notifier(vdev->binding_opaque, idx, true);
+    if (r < 0) {
+        fprintf(stderr, "Error binding host notifier: %d\n", -r);
+        goto fail_host_notifier;
+    }
+
+    file.fd = event_notifier_get_fd(virtio_queue_get_host_notifier(vvq));
+    r = ioctl(dev->control, VHOST_SET_VRING_KICK, &file);
+    if (r) {
+        goto fail_kick;
+    }
+
+    file.fd = event_notifier_get_fd(virtio_queue_get_guest_notifier(vvq));
+    r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);
+    if (r) {
+        goto fail_call;
+    }
+
+    return 0;
+
+fail_call:
+fail_kick:
+    vdev->binding->set_host_notifier(vdev->binding_opaque, idx, false);
+fail_host_notifier:
+    vdev->binding->set_guest_notifier(vdev->binding_opaque, idx, false);
+fail_guest_notifier:
+fail_alloc:
+    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
+                              0, 0);
+fail_alloc_ring:
+    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
+                              0, 0);
+fail_alloc_used:
+    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),
+                              0, 0);
+fail_alloc_avail:
+    cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),
+                              0, 0);
+fail_alloc_desc:
+    return r;
+}
+
+static void vhost_virtqueue_cleanup(struct vhost_dev *dev,
+                                    struct VirtIODevice *vdev,
+                                    struct vhost_virtqueue *vq,
+                                    unsigned idx)
+{
+    struct vhost_vring_state state = {
+        .index = idx,
+    };
+    int r;
+    r = vdev->binding->set_guest_notifier(vdev->binding_opaque, idx, false);
+    if (r < 0) {
+        fprintf(stderr, "vhost VQ %d guest cleanup failed: %d\n", idx, r);
+        fflush(stderr);
+    }
+    assert (r >= 0);
+
+    r = vdev->binding->set_host_notifier(vdev->binding_opaque, idx, false);
+    if (r < 0) {
+        fprintf(stderr, "vhost VQ %d host cleanup failed: %d\n", idx, r);
+        fflush(stderr);
+    }
+    assert (r >= 0);
+    r = ioctl(dev->control, VHOST_GET_VRING_BASE, &state);
+    if (r < 0) {
+        fprintf(stderr, "vhost VQ %d ring restore failed: %d\n", idx, r);
+        fflush(stderr);
+    }
+    virtio_queue_set_last_avail_idx(vdev, idx, state.num);
+    assert (r >= 0);
+    cpu_physical_memory_unmap(vq->ring, virtio_queue_get_ring_size(vdev, idx),
+                              0, virtio_queue_get_ring_size(vdev, idx));
+    cpu_physical_memory_unmap(vq->used, virtio_queue_get_used_size(vdev, idx),
+                              1, virtio_queue_get_used_size(vdev, idx));
+    cpu_physical_memory_unmap(vq->avail, virtio_queue_get_avail_size(vdev, idx),
+                              0, virtio_queue_get_avail_size(vdev, idx));
+    cpu_physical_memory_unmap(vq->desc, virtio_queue_get_desc_size(vdev, idx),
+                              0, virtio_queue_get_desc_size(vdev, idx));
+}
+
+int vhost_dev_init(struct vhost_dev *hdev, int devfd)
+{
+    uint64_t features;
+    int r;
+    if (devfd >= 0) {
+        hdev->control = devfd;
+    } else {
+        hdev->control = open("/dev/vhost-net", O_RDWR);
+        if (hdev->control < 0) {
+            return -errno;
+        }
+    }
+    r = ioctl(hdev->control, VHOST_SET_OWNER, NULL);
+    if (r < 0) {
+        goto fail;
+    }
+
+    r = ioctl(hdev->control, VHOST_GET_FEATURES, &features);
+    if (r < 0) {
+        goto fail;
+    }
+    hdev->features = features;
+
+    hdev->client.set_memory = vhost_client_set_memory;
+    hdev->client.sync_dirty_bitmap = vhost_client_sync_dirty_bitmap;
+    hdev->client.migration_log = vhost_client_migration_log;
+    hdev->mem = qemu_mallocz(offsetof(struct vhost_memory, regions));
+    hdev->log = NULL;
+    hdev->log_size = 0;
+    hdev->log_enabled = false;
+    hdev->started = false;
+    cpu_register_phys_memory_client(&hdev->client);
+    return 0;
+fail:
+    r = -errno;
+    close(hdev->control);
+    return r;
+}
+
+void vhost_dev_cleanup(struct vhost_dev *hdev)
+{
+    cpu_unregister_phys_memory_client(&hdev->client);
+    qemu_free(hdev->mem);
+    close(hdev->control);
+}
+
+int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
+{
+    int i, r;
+
+    r = vhost_dev_set_features(hdev, hdev->log_enabled);
+    if (r < 0) {
+        goto fail;
+    }
+    r = ioctl(hdev->control, VHOST_SET_MEM_TABLE, hdev->mem);
+    if (r < 0) {
+        r = -errno;
+        goto fail;
+    }
+    if (hdev->log_enabled) {
+        hdev->log_size = vhost_get_log_size(hdev);
+        hdev->log = hdev->log_size ?
+            qemu_mallocz(hdev->log_size * sizeof *hdev->log) : NULL;
+        r = ioctl(hdev->control, VHOST_SET_LOG_BASE,
+                  (uint64_t)(unsigned long)hdev->log);
+        if (r < 0) {
+            r = -errno;
+            goto fail;
+        }
+    }
+
+    for (i = 0; i < hdev->nvqs; ++i) {
+        r = vhost_virtqueue_init(hdev,
+                                 vdev,
+                                 hdev->vqs + i,
+                                 i);
+        if (r < 0) {
+            goto fail_vq;
+        }
+    }
+    hdev->started = true;
+
+    return 0;
+fail_vq:
+    while (--i >= 0) {
+        vhost_virtqueue_cleanup(hdev,
+                                vdev,
+                                hdev->vqs + i,
+                                i);
+    }
+fail:
+    return r;
+}
+
+void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev)
+{
+    int i;
+    for (i = 0; i < hdev->nvqs; ++i) {
+        vhost_virtqueue_cleanup(hdev,
+                                vdev,
+                                hdev->vqs + i,
+                                i);
+    }
+    vhost_client_sync_dirty_bitmap(&hdev->client, 0,
+                                   (target_phys_addr_t)~0x0ull);
+    hdev->started = false;
+    qemu_free(hdev->log);
+    hdev->log_size = 0;
+}
diff --git a/hw/vhost.h b/hw/vhost.h
new file mode 100644
index 0000000..86dd834
--- /dev/null
+++ b/hw/vhost.h
@@ -0,0 +1,48 @@ 
+#ifndef VHOST_H
+#define VHOST_H
+
+#include "hw/hw.h"
+#include "hw/virtio.h"
+
+/* Generic structures common for any vhost based device. */
+struct vhost_virtqueue {
+    int kick;
+    int call;
+    void *desc;
+    void *avail;
+    void *used;
+    int num;
+    unsigned long long used_phys;
+    unsigned used_size;
+    void *ring;
+    unsigned long long ring_phys;
+    unsigned ring_size;
+};
+
+typedef unsigned long vhost_log_chunk_t;
+#define VHOST_LOG_PAGE 0x1000
+#define VHOST_LOG_BITS (8 * sizeof(vhost_log_chunk_t))
+#define VHOST_LOG_CHUNK (VHOST_LOG_PAGE * VHOST_LOG_BITS)
+
+struct vhost_memory;
+struct vhost_dev {
+    CPUPhysMemoryClient client;
+    int control;
+    struct vhost_memory *mem;
+    struct vhost_virtqueue *vqs;
+    int nvqs;
+    unsigned long long features;
+    unsigned long long acked_features;
+    unsigned long long backend_features;
+    bool started;
+    bool log_enabled;
+    vhost_log_chunk_t *log;
+    unsigned long long log_size;
+};
+
+int vhost_dev_init(struct vhost_dev *hdev, int devfd);
+void vhost_dev_cleanup(struct vhost_dev *hdev);
+int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev);
+void vhost_dev_stop(struct vhost_dev *hdev, VirtIODevice *vdev);
+
+#endif
diff --git a/hw/vhost_net.c b/hw/vhost_net.c
new file mode 100644
index 0000000..39643f1
--- /dev/null
+++ b/hw/vhost_net.c
@@ -0,0 +1,195 @@ 
+/*
+ * vhost-net support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "net.h"
+#include "net/tap.h"
+
+#include "virtio-net.h"
+#include "vhost_net.h"
+
+#include "config.h"
+
+#ifdef CONFIG_VHOST_NET
+#include <linux/vhost.h>
+#include <sys/eventfd.h>
+#include <sys/socket.h>
+#include <linux/kvm.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/virtio_ring.h>
+#include <netpacket/packet.h>
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <netinet/in.h>
+
+#include <stdio.h>
+
+#include "vhost.h"
+
+struct vhost_net {
+    struct vhost_dev dev;
+    struct vhost_virtqueue vqs[2];
+    int backend;
+    VLANClientState *vc;
+};
+
+unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
+{
+    /* Clear features not supported by host kernel. */
+    if (!(net->dev.features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY))) {
+        features &= ~(1 << VIRTIO_F_NOTIFY_ON_EMPTY);
+    }
+    if (!(net->dev.features & (1 << VIRTIO_RING_F_INDIRECT_DESC))) {
+        features &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC);
+    }
+    return features;
+}
+
+void vhost_net_ack_features(struct vhost_net *net, unsigned features)
+{
+    net->dev.acked_features = net->dev.backend_features;
+    if (features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) {
+        net->dev.acked_features |= (1 << VIRTIO_F_NOTIFY_ON_EMPTY);
+    }
+    if (features & (1 << VIRTIO_RING_F_INDIRECT_DESC)) {
+        net->dev.acked_features |= (1 << VIRTIO_RING_F_INDIRECT_DESC);
+    }
+}
+
+static int vhost_net_get_fd(VLANClientState *backend)
+{
+    switch (backend->info->type) {
+    case NET_CLIENT_TYPE_TAP:
+        return tap_get_fd(backend);
+    default:
+        fprintf(stderr, "vhost-net requires tap backend\n");
+        return -EBADFD;
+    }
+}
+
+struct vhost_net *vhost_net_init(VLANClientState *backend, int devfd)
+{
+    int r;
+    struct vhost_net *net = qemu_malloc(sizeof *net);
+    if (!backend) {
+        fprintf(stderr, "vhost-net requires backend to be setup\n");
+        goto fail;
+    }
+    r = vhost_net_get_fd(backend);
+    if (r < 0) {
+        goto fail;
+    }
+    net->vc = backend;
+    net->dev.backend_features = tap_has_vnet_hdr(backend) ? 0 :
+        (1 << VHOST_NET_F_VIRTIO_NET_HDR);
+    net->backend = r;
+
+    r = vhost_dev_init(&net->dev, devfd);
+    if (r < 0) {
+        goto fail;
+    }
+    if (~net->dev.features & net->dev.backend_features) {
+        fprintf(stderr, "vhost lacks feature mask %llu for backend\n",
+                ~net->dev.features & net->dev.backend_features);
+        vhost_dev_cleanup(&net->dev);
+        goto fail;
+    }
+
+    /* Set sane init value. Override when guest acks. */
+    vhost_net_ack_features(net, 0);
+    return net;
+fail:
+    qemu_free(net);
+    return NULL;
+}
+
+int vhost_net_start(struct vhost_net *net,
+                    VirtIODevice *dev)
+{
+    struct vhost_vring_file file = { };
+    int r;
+
+    net->dev.nvqs = 2;
+    net->dev.vqs = net->vqs;
+    r = vhost_dev_start(&net->dev, dev);
+    if (r < 0) {
+        return r;
+    }
+
+    net->vc->info->poll(net->vc, false);
+    qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
+    file.fd = net->backend;
+    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
+        r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        if (r < 0) {
+            r = -errno;
+            goto fail;
+        }
+    }
+    return 0;
+fail:
+    file.fd = -1;
+    while (--file.index >= 0) {
+        int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        assert(r >= 0);
+    }
+    net->vc->info->poll(net->vc, true);
+    vhost_dev_stop(&net->dev, dev);
+    return r;
+}
+
+void vhost_net_stop(struct vhost_net *net,
+                    VirtIODevice *dev)
+{
+    struct vhost_vring_file file = { .fd = -1 };
+
+    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
+        int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        assert(r >= 0);
+    }
+    net->vc->info->poll(net->vc, true);
+    vhost_dev_stop(&net->dev, dev);
+}
+
+void vhost_net_cleanup(struct vhost_net *net)
+{
+    vhost_dev_cleanup(&net->dev);
+    qemu_free(net);
+}
+#else
+struct vhost_net *vhost_net_init(VLANClientState *backend, int devfd)
+{
+	return NULL;
+}
+
+int vhost_net_start(struct vhost_net *net,
+		    VirtIODevice *dev)
+{
+	return -ENOSYS;
+}
+void vhost_net_stop(struct vhost_net *net,
+		    VirtIODevice *dev)
+{
+}
+
+void vhost_net_cleanup(struct vhost_net *net)
+{
+}
+
+unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
+{
+	return features;
+}
+void vhost_net_ack_features(struct vhost_net *net, unsigned features)
+{
+}
+#endif
diff --git a/hw/vhost_net.h b/hw/vhost_net.h
new file mode 100644
index 0000000..6c18ff7
--- /dev/null
+++ b/hw/vhost_net.h
@@ -0,0 +1,19 @@ 
+#ifndef VHOST_NET_H
+#define VHOST_NET_H
+
+#include "net.h"
+
+struct vhost_net;
+typedef struct vhost_net VHostNetState;
+
+VHostNetState *vhost_net_init(VLANClientState *backend, int devfd);
+
+int vhost_net_start(VHostNetState *net, VirtIODevice *dev);
+void vhost_net_stop(VHostNetState *net, VirtIODevice *dev);
+
+void vhost_net_cleanup(VHostNetState *net);
+
+unsigned vhost_net_get_features(VHostNetState *net, unsigned features);
+void vhost_net_ack_features(VHostNetState *net, unsigned features);
+
+#endif