* [Qemu-devel] [PATCH v2 1/8] raw-posix: add raw_get_aio_fd() for virtio-blk-data-plane
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE Stefan Hajnoczi
` (6 subsequent siblings)
7 siblings, 0 replies; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The raw_get_aio_fd() function allows virtio-blk-data-plane to get the
file descriptor of a raw image file with Linux AIO enabled. This
interface is really a layering violation that can be resolved once the
block layer is able to run outside the global mutex - at that point
virtio-blk-data-plane will switch from custom Linux AIO code to using
the block layer.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
block.h | 9 +++++++++
block/raw-posix.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 43 insertions(+)
diff --git a/block.h b/block.h
index 722c620..2dc6aaf 100644
--- a/block.h
+++ b/block.h
@@ -365,6 +365,15 @@ void bdrv_disable_copy_on_read(BlockDriverState *bs);
void bdrv_set_in_use(BlockDriverState *bs, int in_use);
int bdrv_in_use(BlockDriverState *bs);
+#ifdef CONFIG_LINUX_AIO
+int raw_get_aio_fd(BlockDriverState *bs);
+#else
+static inline int raw_get_aio_fd(BlockDriverState *bs)
+{
+ return -ENOTSUP;
+}
+#endif
+
enum BlockAcctType {
BDRV_ACCT_READ,
BDRV_ACCT_WRITE,
diff --git a/block/raw-posix.c b/block/raw-posix.c
index f2f0404..fc04981 100644
--- a/block/raw-posix.c
+++ b/block/raw-posix.c
@@ -1768,6 +1768,40 @@ static BlockDriver bdrv_host_cdrom = {
};
#endif /* __FreeBSD__ */
+#ifdef CONFIG_LINUX_AIO
+/**
+ * Return the file descriptor for Linux AIO
+ *
+ * This function is a layering violation and should be removed when it becomes
+ * possible to call the block layer outside the global mutex. It allows the
+ * caller to hijack the file descriptor so I/O can be performed outside the
+ * block layer.
+ */
+int raw_get_aio_fd(BlockDriverState *bs)
+{
+ BDRVRawState *s;
+
+ if (!bs->drv) {
+ return -ENOMEDIUM;
+ }
+
+ if (bs->drv == bdrv_find_format("raw")) {
+ bs = bs->file;
+ }
+
+ /* raw-posix has several protocols so just check for raw_aio_readv */
+ if (bs->drv->bdrv_aio_readv != raw_aio_readv) {
+ return -ENOTSUP;
+ }
+
+ s = bs->opaque;
+ if (!s->use_aio) {
+ return -ENOTSUP;
+ }
+ return s->fd;
+}
+#endif /* CONFIG_LINUX_AIO */
+
static void bdrv_file_init(void)
{
/*
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 1/8] raw-posix: add raw_get_aio_fd() for virtio-blk-data-plane Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-21 18:17 ` mdroth
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code Stefan Hajnoczi
` (5 subsequent siblings)
7 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The virtio-blk-data-plane feature only works with Linux AIO. Therefore
add a ./configure option and necessary checks to implement this
dependency.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
configure | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/configure b/configure
index 780b19a..633ba6d 100755
--- a/configure
+++ b/configure
@@ -223,6 +223,7 @@ libiscsi=""
coroutine=""
seccomp=""
glusterfs=""
+virtio_blk_data_plane=""
# parse CC options first
for opt do
@@ -871,6 +872,10 @@ for opt do
;;
--enable-glusterfs) glusterfs="yes"
;;
+ --disable-virtio-blk-data-plane) virtio_blk_data_plane="no"
+ ;;
+ --enable-virtio-blk-data-plane) virtio_blk_data_plane="yes"
+ ;;
*) echo "ERROR: unknown option $opt"; show_help="yes"
;;
esac
@@ -2233,6 +2238,17 @@ EOF
fi
##########################################
+# adjust virtio-blk-data-plane based on linux-aio
+
+if test "$virtio_blk_data_plane" = "yes" -a \
+ "$linux_aio" != "yes" ; then
+ echo "Error: virtio-blk-data-plane requires Linux AIO, please try --enable-linux-aio"
+ exit 1
+elif test -z "$virtio_blk_data_plane" ; then
+ virtio_blk_data_plane=$linux_aio
+fi
+
+##########################################
# attr probe
if test "$attr" != "no" ; then
@@ -3235,6 +3251,7 @@ echo "build guest agent $guest_agent"
echo "seccomp support $seccomp"
echo "coroutine backend $coroutine_backend"
echo "GlusterFS support $glusterfs"
+echo "virtio-blk-data-plane $virtio_blk_data_plane"
if test "$sdl_too_old" = "yes"; then
echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -3581,6 +3598,10 @@ if test "$glusterfs" = "yes" ; then
echo "CONFIG_GLUSTERFS=y" >> $config_host_mak
fi
+if test "$virtio_blk_data_plane" = "yes" ; then
+ echo "CONFIG_VIRTIO_BLK_DATA_PLANE=y" >> $config_host_mak
+fi
+
# USB host support
case "$usb" in
linux)
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE Stefan Hajnoczi
@ 2012-11-21 18:17 ` mdroth
2012-11-21 18:29 ` Stefan Hajnoczi
0 siblings, 1 reply; 21+ messages in thread
From: mdroth @ 2012-11-21 18:17 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 01:31:46PM +0100, Stefan Hajnoczi wrote:
> The virtio-blk-data-plane feature only works with Linux AIO. Therefore
> add a ./configure option and necessary checks to implement this
> dependency.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> configure | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/configure b/configure
> index 780b19a..633ba6d 100755
> --- a/configure
> +++ b/configure
> @@ -223,6 +223,7 @@ libiscsi=""
> coroutine=""
> seccomp=""
> glusterfs=""
> +virtio_blk_data_plane=""
>
> # parse CC options first
> for opt do
> @@ -871,6 +872,10 @@ for opt do
> ;;
> --enable-glusterfs) glusterfs="yes"
> ;;
> + --disable-virtio-blk-data-plane) virtio_blk_data_plane="no"
> + ;;
> + --enable-virtio-blk-data-plane) virtio_blk_data_plane="yes"
> + ;;
> *) echo "ERROR: unknown option $opt"; show_help="yes"
> ;;
> esac
> @@ -2233,6 +2238,17 @@ EOF
> fi
>
> ##########################################
> +# adjust virtio-blk-data-plane based on linux-aio
> +
> +if test "$virtio_blk_data_plane" = "yes" -a \
> + "$linux_aio" != "yes" ; then
> + echo "Error: virtio-blk-data-plane requires Linux AIO, please try --enable-linux-aio"
> + exit 1
> +elif test -z "$virtio_blk_data_plane" ; then
> + virtio_blk_data_plane=$linux_aio
> +fi
$linux_aio gets set automatically if the user has libaio installed and
doesn't specify --disable-linux-aio, so this ends up enabling dataplane by
default in a lot of situations. Since it's experimental I think it should only
be enabled if we pass --enable-virtio-blk-data-plane explicitly.
^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE
2012-11-21 18:17 ` mdroth
@ 2012-11-21 18:29 ` Stefan Hajnoczi
2012-11-21 18:45 ` mdroth
0 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-21 18:29 UTC (permalink / raw)
To: mdroth
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel,
Khoa Huynh, Stefan Hajnoczi, Paolo Bonzini, Asias He
On Wed, Nov 21, 2012 at 7:17 PM, mdroth <mdroth@linux.vnet.ibm.com> wrote:
> On Tue, Nov 20, 2012 at 01:31:46PM +0100, Stefan Hajnoczi wrote:
>> @@ -2233,6 +2238,17 @@ EOF
>> fi
>>
>> ##########################################
>> +# adjust virtio-blk-data-plane based on linux-aio
>> +
>> +if test "$virtio_blk_data_plane" = "yes" -a \
>> + "$linux_aio" != "yes" ; then
>> + echo "Error: virtio-blk-data-plane requires Linux AIO, please try --enable-linux-aio"
>> + exit 1
>> +elif test -z "$virtio_blk_data_plane" ; then
>> + virtio_blk_data_plane=$linux_aio
>> +fi
>
> $linux_aio gets set automatically if the user has libaio installed and
> doesn't specify --disable-linux-aio, so this ends up enabling dataplane by
> default in a lot of situations. Since it's experimental I think it should only
> be enabled if we pass --enable-virtio-blk-data-plane explicitly.
I expect downstreams to enable this feature. Requiring package
maintainers to add --enable-virtio-blk-data-one explicitly is probably
going to cause more work than any benefits of disabling it by default.
The feature has no effect unless -device
virtio-blk-pci,x-data-plane-on is used. Code size is <12 KB on x86_64
and contains nothing especially risky from a security perspective.
That said, if there is a strong feeling this should be disabled by
default, I can switch it to default off.
Stefan
^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE
2012-11-21 18:29 ` Stefan Hajnoczi
@ 2012-11-21 18:45 ` mdroth
0 siblings, 0 replies; 21+ messages in thread
From: mdroth @ 2012-11-21 18:45 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel,
Khoa Huynh, Stefan Hajnoczi, Paolo Bonzini, Asias He
On Wed, Nov 21, 2012 at 07:29:21PM +0100, Stefan Hajnoczi wrote:
> On Wed, Nov 21, 2012 at 7:17 PM, mdroth <mdroth@linux.vnet.ibm.com> wrote:
> > On Tue, Nov 20, 2012 at 01:31:46PM +0100, Stefan Hajnoczi wrote:
> >> @@ -2233,6 +2238,17 @@ EOF
> >> fi
> >>
> >> ##########################################
> >> +# adjust virtio-blk-data-plane based on linux-aio
> >> +
> >> +if test "$virtio_blk_data_plane" = "yes" -a \
> >> + "$linux_aio" != "yes" ; then
> >> + echo "Error: virtio-blk-data-plane requires Linux AIO, please try --enable-linux-aio"
> >> + exit 1
> >> +elif test -z "$virtio_blk_data_plane" ; then
> >> + virtio_blk_data_plane=$linux_aio
> >> +fi
> >
> > $linux_aio gets set automatically if the user has libaio installed and
> > doesn't specify --disable-linux-aio, so this ends up enabling dataplane by
> > default in a lot of situations. Since it's experimental I think it should only
> > be enabled if we pass --enable-virtio-blk-data-plane explicitly.
>
> I expect downstreams to enable this feature. Requiring package
> maintainers to add --enable-virtio-blk-data-one explicitly is probably
> going to cause more work than any benefits of disabling it by default.
>
> The feature has no effect unless -device
> virtio-blk-pci,x-data-plane-on is used. Code size is <12 KB on x86_64
> and contains nothing especially risky from a security perspective.
>
> That said, if there is a strong feeling this should be disabled by
> default, I can switch it to default off.
No, sorry for the noise. I was playing around with it locally and
noticed it enabled by default, but wasn't accounting for the fact that
you still need to enable the x-data-plane option to use it. I don't
think it hurts to compile in the support by default.
>
> Stefan
>
^ permalink raw reply [flat|nested] 21+ messages in thread
* [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 1/8] raw-posix: add raw_get_aio_fd() for virtio-blk-data-plane Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 2/8] configure: add CONFIG_VIRTIO_BLK_DATA_PLANE Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 18:24 ` Don Koch
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 4/8] dataplane: add virtqueue vring code Stefan Hajnoczi
` (4 subsequent siblings)
7 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The data plane thread needs to map guest physical addresses to host
pointers. Normally this is done with cpu_physical_memory_map() but the
function assumes the global mutex is held. The data plane thread does
not touch the global mutex and therefore needs a thread-safe memory
mapping mechanism.
Hostmem registers a MemoryListener similar to how vhost collects and
pushes memory region information into the kernel. There is a
fine-grained lock on the regions list which is held during lookup and
when installing a new regions list.
When the physical memory map changes the MemoryListener callbacks are
invoked. They build up a new list of memory regions which is finally
installed when the list has been completed.
Note that this approach is not safe across memory hotplug because mapped
pointers may still be in used across memory unplug. However, this is
currently a problem for QEMU in general and needs to be addressed in the
future.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/dataplane/Makefile.objs | 3 +
hw/dataplane/hostmem.c | 165 +++++++++++++++++++++++++++++++++++++++++++++
hw/dataplane/hostmem.h | 52 ++++++++++++++
3 files changed, 220 insertions(+)
create mode 100644 hw/dataplane/Makefile.objs
create mode 100644 hw/dataplane/hostmem.c
create mode 100644 hw/dataplane/hostmem.h
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
new file mode 100644
index 0000000..8c8dea1
--- /dev/null
+++ b/hw/dataplane/Makefile.objs
@@ -0,0 +1,3 @@
+ifeq ($(CONFIG_VIRTIO), y)
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o
+endif
diff --git a/hw/dataplane/hostmem.c b/hw/dataplane/hostmem.c
new file mode 100644
index 0000000..ac9d613
--- /dev/null
+++ b/hw/dataplane/hostmem.c
@@ -0,0 +1,165 @@
+/*
+ * Thread-safe guest to host memory mapping
+ *
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "exec-memory.h"
+#include "hostmem.h"
+
+static int hostmem_lookup_cmp(const void *phys_, const void *region_)
+{
+ hwaddr phys = *(const hwaddr *)phys_;
+ const HostmemRegion *region = region_;
+
+ if (phys < region->guest_addr) {
+ return -1;
+ } else if (phys >= region->guest_addr + region->size) {
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+/**
+ * Map guest physical address to host pointer
+ */
+void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write)
+{
+ HostmemRegion *region;
+ void *host_addr = NULL;
+ hwaddr offset_within_region;
+
+ qemu_mutex_lock(&hostmem->current_regions_lock);
+ region = bsearch(&phys, hostmem->current_regions,
+ hostmem->num_current_regions,
+ sizeof(hostmem->current_regions[0]),
+ hostmem_lookup_cmp);
+ if (!region) {
+ goto out;
+ }
+ if (is_write && region->readonly) {
+ goto out;
+ }
+ offset_within_region = phys - region->guest_addr;
+ if (offset_within_region + len <= region->size) {
+ host_addr = region->host_addr + offset_within_region;
+ }
+out:
+ qemu_mutex_unlock(&hostmem->current_regions_lock);
+
+ return host_addr;
+}
+
+/**
+ * Install new regions list
+ */
+static void hostmem_listener_commit(MemoryListener *listener)
+{
+ Hostmem *hostmem = container_of(listener, Hostmem, listener);
+
+ qemu_mutex_lock(&hostmem->current_regions_lock);
+ g_free(hostmem->current_regions);
+ hostmem->current_regions = hostmem->new_regions;
+ hostmem->num_current_regions = hostmem->num_new_regions;
+ qemu_mutex_unlock(&hostmem->current_regions_lock);
+
+ /* Reset new regions list */
+ hostmem->new_regions = NULL;
+ hostmem->num_new_regions = 0;
+}
+
+/**
+ * Add a MemoryRegionSection to the new regions list
+ */
+static void hostmem_append_new_region(Hostmem *hostmem,
+ MemoryRegionSection *section)
+{
+ void *ram_ptr = memory_region_get_ram_ptr(section->mr);
+ size_t num = hostmem->num_new_regions;
+ size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]);
+
+ hostmem->new_regions = g_realloc(hostmem->new_regions, new_size);
+ hostmem->new_regions[num] = (HostmemRegion){
+ .host_addr = ram_ptr + section->offset_within_region,
+ .guest_addr = section->offset_within_address_space,
+ .size = section->size,
+ .readonly = section->readonly,
+ };
+ hostmem->num_new_regions++;
+}
+
+static void hostmem_listener_region_add(MemoryListener *listener,
+ MemoryRegionSection *section)
+{
+ Hostmem *hostmem = container_of(listener, Hostmem, listener);
+
+ if (memory_region_is_ram(section->mr)) {
+ hostmem_append_new_region(hostmem, section);
+ }
+}
+
+/* We don't implement most MemoryListener callbacks, use these nop stubs */
+static void hostmem_listener_nop(MemoryListener *listener)
+{
+}
+
+static void hostmem_listener_section_nop(MemoryListener *listener,
+ MemoryRegionSection *section)
+{
+}
+
+static void hostmem_listener_eventfd_nop(MemoryListener *listener,
+ MemoryRegionSection *section,
+ bool match_data, uint64_t data,
+ EventNotifier *e)
+{
+}
+
+static void hostmem_listener_coalesced_mmio_nop(MemoryListener *listener,
+ MemoryRegionSection *section,
+ hwaddr addr, hwaddr len)
+{
+}
+
+void hostmem_init(Hostmem *hostmem)
+{
+ memset(hostmem, 0, sizeof(*hostmem));
+
+ hostmem->listener = (MemoryListener){
+ .begin = hostmem_listener_nop,
+ .commit = hostmem_listener_commit,
+ .region_add = hostmem_listener_region_add,
+ .region_del = hostmem_listener_section_nop,
+ .region_nop = hostmem_listener_region_add,
+ .log_start = hostmem_listener_section_nop,
+ .log_stop = hostmem_listener_section_nop,
+ .log_sync = hostmem_listener_section_nop,
+ .log_global_start = hostmem_listener_nop,
+ .log_global_stop = hostmem_listener_nop,
+ .eventfd_add = hostmem_listener_eventfd_nop,
+ .eventfd_del = hostmem_listener_eventfd_nop,
+ .coalesced_mmio_add = hostmem_listener_coalesced_mmio_nop,
+ .coalesced_mmio_del = hostmem_listener_coalesced_mmio_nop,
+ .priority = 10,
+ };
+
+ memory_listener_register(&hostmem->listener, &address_space_memory);
+ if (hostmem->num_new_regions > 0) {
+ hostmem_listener_commit(&hostmem->listener);
+ }
+}
+
+void hostmem_finalize(Hostmem *hostmem)
+{
+ memory_listener_unregister(&hostmem->listener);
+ g_free(hostmem->new_regions);
+ g_free(hostmem->current_regions);
+}
diff --git a/hw/dataplane/hostmem.h b/hw/dataplane/hostmem.h
new file mode 100644
index 0000000..a833b74
--- /dev/null
+++ b/hw/dataplane/hostmem.h
@@ -0,0 +1,52 @@
+/*
+ * Thread-safe guest to host memory mapping
+ *
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef HOSTMEM_H
+#define HOSTMEM_H
+
+#include "memory.h"
+#include "qemu-thread.h"
+
+typedef struct {
+ void *host_addr;
+ hwaddr guest_addr;
+ uint64_t size;
+ bool readonly;
+} HostmemRegion;
+
+typedef struct {
+ /* The listener is invoked when regions change and a new list of regions is
+ * built up completely before they are installed.
+ */
+ MemoryListener listener;
+ HostmemRegion *new_regions;
+ size_t num_new_regions;
+
+ /* Current regions are accessed from multiple threads either to lookup
+ * addresses or to install a new list of regions. The lock protects the
+ * pointer and the regions.
+ */
+ QemuMutex current_regions_lock;
+ HostmemRegion *current_regions;
+ size_t num_current_regions;
+} Hostmem;
+
+void hostmem_init(Hostmem *hostmem);
+void hostmem_finalize(Hostmem *hostmem);
+
+/**
+ * Map a guest physical address to a pointer
+ */
+void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write);
+
+#endif /* HOSTMEM_H */
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code Stefan Hajnoczi
@ 2012-11-20 18:24 ` Don Koch
2012-11-21 7:59 ` Stefan Hajnoczi
0 siblings, 1 reply; 21+ messages in thread
From: Don Koch @ 2012-11-20 18:24 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Paolo Bonzini, asias
On 11/20/2012 07:31 AM, Stefan Hajnoczi wrote:
> The data plane thread needs to map guest physical addresses to host
> pointers. Normally this is done with cpu_physical_memory_map() but the
> function assumes the global mutex is held. The data plane thread does
> not touch the global mutex and therefore needs a thread-safe memory
> mapping mechanism.
>
> Hostmem registers a MemoryListener similar to how vhost collects and
> pushes memory region information into the kernel. There is a
> fine-grained lock on the regions list which is held during lookup and
> when installing a new regions list.
>
> When the physical memory map changes the MemoryListener callbacks are
> invoked. They build up a new list of memory regions which is finally
> installed when the list has been completed.
>
> Note that this approach is not safe across memory hotplug because mapped
> pointers may still be in used across memory unplug. However, this is
> currently a problem for QEMU in general and needs to be addressed in the
> future.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/dataplane/Makefile.objs | 3 +
> hw/dataplane/hostmem.c | 165 +++++++++++++++++++++++++++++++++++++++++++++
> hw/dataplane/hostmem.h | 52 ++++++++++++++
> 3 files changed, 220 insertions(+)
> create mode 100644 hw/dataplane/Makefile.objs
> create mode 100644 hw/dataplane/hostmem.c
> create mode 100644 hw/dataplane/hostmem.h
>
> diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
> new file mode 100644
> index 0000000..8c8dea1
> --- /dev/null
> +++ b/hw/dataplane/Makefile.objs
> @@ -0,0 +1,3 @@
> +ifeq ($(CONFIG_VIRTIO), y)
> +common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o
> +endif
> diff --git a/hw/dataplane/hostmem.c b/hw/dataplane/hostmem.c
> new file mode 100644
> index 0000000..ac9d613
> --- /dev/null
> +++ b/hw/dataplane/hostmem.c
> @@ -0,0 +1,165 @@
> +/*
> + * Thread-safe guest to host memory mapping
> + *
> + * Copyright 2012 Red Hat, Inc. and/or its affiliates
> + *
> + * Authors:
> + * Stefan Hajnoczi <stefanha@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "exec-memory.h"
> +#include "hostmem.h"
> +
> +static int hostmem_lookup_cmp(const void *phys_, const void *region_)
> +{
> + hwaddr phys = *(const hwaddr *)phys_;
> + const HostmemRegion *region = region_;
> +
> + if (phys < region->guest_addr) {
> + return -1;
> + } else if (phys >= region->guest_addr + region->size) {
> + return 1;
> + } else {
> + return 0;
> + }
> +}
> +
> +/**
> + * Map guest physical address to host pointer
> + */
> +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write)
> +{
> + HostmemRegion *region;
> + void *host_addr = NULL;
> + hwaddr offset_within_region;
> +
> + qemu_mutex_lock(&hostmem->current_regions_lock);
> + region = bsearch(&phys, hostmem->current_regions,
> + hostmem->num_current_regions,
> + sizeof(hostmem->current_regions[0]),
> + hostmem_lookup_cmp);
> + if (!region) {
> + goto out;
> + }
> + if (is_write && region->readonly) {
> + goto out;
> + }
> + offset_within_region = phys - region->guest_addr;
> + if (offset_within_region + len <= region->size) {
> + host_addr = region->host_addr + offset_within_region;
> + }
> +out:
> + qemu_mutex_unlock(&hostmem->current_regions_lock);
> +
> + return host_addr;
> +}
> +
> +/**
> + * Install new regions list
> + */
> +static void hostmem_listener_commit(MemoryListener *listener)
> +{
> + Hostmem *hostmem = container_of(listener, Hostmem, listener);
> +
> + qemu_mutex_lock(&hostmem->current_regions_lock);
> + g_free(hostmem->current_regions);
> + hostmem->current_regions = hostmem->new_regions;
> + hostmem->num_current_regions = hostmem->num_new_regions;
> + qemu_mutex_unlock(&hostmem->current_regions_lock);
> +
> + /* Reset new regions list */
> + hostmem->new_regions = NULL;
> + hostmem->num_new_regions = 0;
> +}
> +
> +/**
> + * Add a MemoryRegionSection to the new regions list
> + */
> +static void hostmem_append_new_region(Hostmem *hostmem,
> + MemoryRegionSection *section)
> +{
> + void *ram_ptr = memory_region_get_ram_ptr(section->mr);
> + size_t num = hostmem->num_new_regions;
> + size_t new_size = (num + 1) * sizeof(hostmem->new_regions[0]);
> +
> + hostmem->new_regions = g_realloc(hostmem->new_regions, new_size);
> + hostmem->new_regions[num] = (HostmemRegion){
> + .host_addr = ram_ptr + section->offset_within_region,
> + .guest_addr = section->offset_within_address_space,
> + .size = section->size,
> + .readonly = section->readonly,
> + };
> + hostmem->num_new_regions++;
> +}
> +
> +static void hostmem_listener_region_add(MemoryListener *listener,
> + MemoryRegionSection *section)
> +{
> + Hostmem *hostmem = container_of(listener, Hostmem, listener);
> +
> + if (memory_region_is_ram(section->mr)) {
> + hostmem_append_new_region(hostmem, section);
> + }
> +}
> +
> +/* We don't implement most MemoryListener callbacks, use these nop stubs */
> +static void hostmem_listener_nop(MemoryListener *listener)
> +{
> +}
> +
> +static void hostmem_listener_section_nop(MemoryListener *listener,
> + MemoryRegionSection *section)
> +{
> +}
> +
> +static void hostmem_listener_eventfd_nop(MemoryListener *listener,
> + MemoryRegionSection *section,
> + bool match_data, uint64_t data,
> + EventNotifier *e)
> +{
> +}
> +
> +static void hostmem_listener_coalesced_mmio_nop(MemoryListener *listener,
> + MemoryRegionSection *section,
> + hwaddr addr, hwaddr len)
> +{
> +}
> +
> +void hostmem_init(Hostmem *hostmem)
> +{
> + memset(hostmem, 0, sizeof(*hostmem));
> +
> + hostmem->listener = (MemoryListener){
> + .begin = hostmem_listener_nop,
> + .commit = hostmem_listener_commit,
> + .region_add = hostmem_listener_region_add,
> + .region_del = hostmem_listener_section_nop,
> + .region_nop = hostmem_listener_region_add,
Really?
> + .log_start = hostmem_listener_section_nop,
> + .log_stop = hostmem_listener_section_nop,
> + .log_sync = hostmem_listener_section_nop,
> + .log_global_start = hostmem_listener_nop,
> + .log_global_stop = hostmem_listener_nop,
> + .eventfd_add = hostmem_listener_eventfd_nop,
> + .eventfd_del = hostmem_listener_eventfd_nop,
> + .coalesced_mmio_add = hostmem_listener_coalesced_mmio_nop,
> + .coalesced_mmio_del = hostmem_listener_coalesced_mmio_nop,
> + .priority = 10,
> + };
> +
> + memory_listener_register(&hostmem->listener, &address_space_memory);
> + if (hostmem->num_new_regions > 0) {
> + hostmem_listener_commit(&hostmem->listener);
> + }
> +}
> +
> +void hostmem_finalize(Hostmem *hostmem)
> +{
> + memory_listener_unregister(&hostmem->listener);
> + g_free(hostmem->new_regions);
> + g_free(hostmem->current_regions);
> +}
> diff --git a/hw/dataplane/hostmem.h b/hw/dataplane/hostmem.h
> new file mode 100644
> index 0000000..a833b74
> --- /dev/null
> +++ b/hw/dataplane/hostmem.h
> @@ -0,0 +1,52 @@
> +/*
> + * Thread-safe guest to host memory mapping
> + *
> + * Copyright 2012 Red Hat, Inc. and/or its affiliates
> + *
> + * Authors:
> + * Stefan Hajnoczi <stefanha@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef HOSTMEM_H
> +#define HOSTMEM_H
> +
> +#include "memory.h"
> +#include "qemu-thread.h"
> +
> +typedef struct {
> + void *host_addr;
> + hwaddr guest_addr;
> + uint64_t size;
> + bool readonly;
> +} HostmemRegion;
> +
> +typedef struct {
> + /* The listener is invoked when regions change and a new list of regions is
> + * built up completely before they are installed.
> + */
> + MemoryListener listener;
> + HostmemRegion *new_regions;
> + size_t num_new_regions;
> +
> + /* Current regions are accessed from multiple threads either to lookup
> + * addresses or to install a new list of regions. The lock protects the
> + * pointer and the regions.
> + */
> + QemuMutex current_regions_lock;
> + HostmemRegion *current_regions;
> + size_t num_current_regions;
> +} Hostmem;
> +
> +void hostmem_init(Hostmem *hostmem);
> +void hostmem_finalize(Hostmem *hostmem);
> +
> +/**
> + * Map a guest physical address to a pointer
> + */
> +void *hostmem_lookup(Hostmem *hostmem, hwaddr phys, hwaddr len, bool is_write);
> +
> +#endif /* HOSTMEM_H */
-d
^ permalink raw reply [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code
2012-11-20 18:24 ` Don Koch
@ 2012-11-21 7:59 ` Stefan Hajnoczi
2012-11-26 15:31 ` Don Koch
0 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-21 7:59 UTC (permalink / raw)
To: Don Koch
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 01:24:08PM -0500, Don Koch wrote:
> On 11/20/2012 07:31 AM, Stefan Hajnoczi wrote:
> > +void hostmem_init(Hostmem *hostmem)
> > +{
> > + memset(hostmem, 0, sizeof(*hostmem));
> > +
> > + hostmem->listener = (MemoryListener){
> > + .begin = hostmem_listener_nop,
> > + .commit = hostmem_listener_commit,
> > + .region_add = hostmem_listener_region_add,
> > + .region_del = hostmem_listener_section_nop,
> > + .region_nop = hostmem_listener_region_add,
> Really?
Yes. I will rename the function in the next version of the patch to
make it clear this is correct.
Since we rebuild the entire regions list on every update transaction, we
care about the "nop" (unchanged) regions too. They need to be added to
the new list we're building.
The deleted regions are ignored because we're building a new regions
list from scratch anyway.
Stefan
^ permalink raw reply [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code
2012-11-21 7:59 ` Stefan Hajnoczi
@ 2012-11-26 15:31 ` Don Koch
0 siblings, 0 replies; 21+ messages in thread
From: Don Koch @ 2012-11-26 15:31 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
On 11/21/2012 02:59 AM, Stefan Hajnoczi wrote:
> On Tue, Nov 20, 2012 at 01:24:08PM -0500, Don Koch wrote:
>> On 11/20/2012 07:31 AM, Stefan Hajnoczi wrote:
>>> +void hostmem_init(Hostmem *hostmem)
>>> +{
>>> + memset(hostmem, 0, sizeof(*hostmem));
>>> +
>>> + hostmem->listener = (MemoryListener){
>>> + .begin = hostmem_listener_nop,
>>> + .commit = hostmem_listener_commit,
>>> + .region_add = hostmem_listener_region_add,
>>> + .region_del = hostmem_listener_section_nop,
>>> + .region_nop = hostmem_listener_region_add,
>> Really?
> Yes. I will rename the function in the next version of the patch to
> make it clear this is correct.
>
> Since we rebuild the entire regions list on every update transaction, we
> care about the "nop" (unchanged) regions too. They need to be added to
> the new list we're building.
>
> The deleted regions are ignored because we're building a new regions
> list from scratch anyway.
>
> Stefan
Ah, OK. I caught this mail later than my last response (for whatever
reason, the last patch you sent
went to my inbox, this response got dumped in my qemu folder - go figure).
-d
^ permalink raw reply [flat|nested] 21+ messages in thread
* [Qemu-devel] [PATCH v2 4/8] dataplane: add virtqueue vring code
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
` (2 preceding siblings ...)
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 3/8] dataplane: add host memory mapping code Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 5/8] dataplane: add event loop Stefan Hajnoczi
` (3 subsequent siblings)
7 siblings, 0 replies; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The virtio-blk-data-plane cannot access memory using the usual QEMU
functions since it executes outside the global mutex and the memory APIs
are this time are not thread-safe.
This patch introduces a virtqueue module based on the kernel's vhost
vring code. The trick is that we map guest memory ahead of time and
access it cheaply outside the global mutex.
Once the hardware emulation code can execute outside the global mutex it
will be possible to drop this code.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/Makefile.objs | 2 +-
hw/dataplane/Makefile.objs | 2 +-
hw/dataplane/vring.c | 344 +++++++++++++++++++++++++++++++++++++++++++++
hw/dataplane/vring.h | 56 ++++++++
trace-events | 3 +
5 files changed, 405 insertions(+), 2 deletions(-)
create mode 100644 hw/dataplane/vring.c
create mode 100644 hw/dataplane/vring.h
diff --git a/hw/Makefile.objs b/hw/Makefile.objs
index ea46f81..db87fbf 100644
--- a/hw/Makefile.objs
+++ b/hw/Makefile.objs
@@ -1,4 +1,4 @@
-common-obj-y = usb/ ide/
+common-obj-y = usb/ ide/ dataplane/
common-obj-y += loader.o
common-obj-$(CONFIG_VIRTIO) += virtio-console.o
common-obj-$(CONFIG_VIRTIO) += virtio-rng.o
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
index 8c8dea1..34e6d57 100644
--- a/hw/dataplane/Makefile.objs
+++ b/hw/dataplane/Makefile.objs
@@ -1,3 +1,3 @@
ifeq ($(CONFIG_VIRTIO), y)
-common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o
endif
diff --git a/hw/dataplane/vring.c b/hw/dataplane/vring.c
new file mode 100644
index 0000000..2632fbd
--- /dev/null
+++ b/hw/dataplane/vring.c
@@ -0,0 +1,344 @@
+/* Copyright 2012 Red Hat, Inc.
+ * Copyright IBM, Corp. 2012
+ *
+ * Based on Linux vhost code:
+ * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2006 Rusty Russell IBM Corporation
+ *
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * Inspiration, some code, and most witty comments come from
+ * Documentation/virtual/lguest/lguest.c, by Rusty Russell
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#include "trace.h"
+#include "hw/dataplane/vring.h"
+
+/* Map the guest's vring to host memory */
+bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
+{
+ hwaddr vring_addr = virtio_queue_get_ring_addr(vdev, n);
+ hwaddr vring_size = virtio_queue_get_ring_size(vdev, n);
+ void *vring_ptr;
+
+ vring->broken = false;
+
+ hostmem_init(&vring->hostmem);
+ vring_ptr = hostmem_lookup(&vring->hostmem, vring_addr, vring_size, true);
+ if (!vring_ptr) {
+ error_report("Failed to map vring "
+ "addr %#" HWADDR_PRIx " size %" HWADDR_PRIu,
+ vring_addr, vring_size);
+ vring->broken = true;
+ return false;
+ }
+
+ vring_init(&vring->vr, virtio_queue_get_num(vdev, n), vring_ptr, 4096);
+
+ vring->last_avail_idx = 0;
+ vring->last_used_idx = 0;
+ vring->signalled_used = 0;
+ vring->signalled_used_valid = false;
+
+ trace_vring_setup(virtio_queue_get_ring_addr(vdev, n),
+ vring->vr.desc, vring->vr.avail, vring->vr.used);
+ return true;
+}
+
+void vring_teardown(Vring *vring)
+{
+ hostmem_finalize(&vring->hostmem);
+}
+
+/* Toggle guest->host notifies */
+void vring_set_notification(VirtIODevice *vdev, Vring *vring, bool enable)
+{
+ if (vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
+ if (enable) {
+ vring_avail_event(&vring->vr) = vring->vr.avail->idx;
+ }
+ } else if (enable) {
+ vring->vr.used->flags &= ~VRING_USED_F_NO_NOTIFY;
+ } else {
+ vring->vr.used->flags |= VRING_USED_F_NO_NOTIFY;
+ }
+}
+
+/* This is stolen from linux/drivers/vhost/vhost.c:vhost_notify() */
+bool vring_should_notify(VirtIODevice *vdev, Vring *vring)
+{
+ uint16_t old, new;
+ bool v;
+ /* Flush out used index updates. This is paired
+ * with the barrier that the Guest executes when enabling
+ * interrupts. */
+ smp_mb();
+
+ if ((vdev->guest_features & VIRTIO_F_NOTIFY_ON_EMPTY) &&
+ unlikely(vring->vr.avail->idx == vring->last_avail_idx)) {
+ return true;
+ }
+
+ if (!(vdev->guest_features & VIRTIO_RING_F_EVENT_IDX)) {
+ return !(vring->vr.avail->flags & VRING_AVAIL_F_NO_INTERRUPT);
+ }
+ old = vring->signalled_used;
+ v = vring->signalled_used_valid;
+ new = vring->signalled_used = vring->last_used_idx;
+ vring->signalled_used_valid = true;
+
+ if (unlikely(!v)) {
+ return true;
+ }
+
+ return vring_need_event(vring_used_event(&vring->vr), new, old);
+}
+
+/* This is stolen from linux-2.6/drivers/vhost/vhost.c. */
+static int get_indirect(Vring *vring,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vring_desc *indirect)
+{
+ struct vring_desc desc;
+ unsigned int i = 0, count, found = 0;
+
+ /* Sanity check */
+ if (unlikely(indirect->len % sizeof desc)) {
+ error_report("Invalid length in indirect descriptor: "
+ "len %#x not multiple of %#zx",
+ indirect->len, sizeof desc);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ count = indirect->len / sizeof desc;
+ /* Buffers are chained via a 16 bit next field, so
+ * we can have at most 2^16 of these. */
+ if (unlikely(count > USHRT_MAX + 1)) {
+ error_report("Indirect buffer length too big: %d", indirect->len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ /* Point to translate indirect desc chain */
+ indirect = hostmem_lookup(&vring->hostmem, indirect->addr, indirect->len,
+ false);
+ if (!indirect) {
+ error_report("Failed to map indirect desc chain "
+ "addr %#" PRIx64 " len %u",
+ (uint64_t)indirect->addr, indirect->len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ /* We will use the result as an address to read from, so most
+ * architectures only need a compiler barrier here. */
+ barrier(); /* read_barrier_depends(); */
+
+ do {
+ if (unlikely(++found > count)) {
+ error_report("Loop detected: last one at %u "
+ "indirect size %u", i, count);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ desc = *indirect++;
+ if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
+ error_report("Nested indirect descriptor");
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ /* Stop for now if there are not enough iovecs available. */
+ if (iov >= iov_end) {
+ return -ENOBUFS;
+ }
+
+ iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
+ desc.flags & VRING_DESC_F_WRITE);
+ if (!iov->iov_base) {
+ error_report("Failed to map indirect descriptor"
+ "addr %#" PRIx64 " len %u",
+ (uint64_t)desc.addr, desc.len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ iov->iov_len = desc.len;
+ iov++;
+
+ /* If this is an input descriptor, increment that count. */
+ if (desc.flags & VRING_DESC_F_WRITE) {
+ *in_num += 1;
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (unlikely(*in_num)) {
+ error_report("Indirect descriptor "
+ "has out after in: idx %d", i);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ *out_num += 1;
+ }
+ i = desc.next;
+ } while (desc.flags & VRING_DESC_F_NEXT);
+ return 0;
+}
+
+/* This looks in the virtqueue and for the first available buffer, and converts
+ * it to an iovec for convenient access. Since descriptors consist of some
+ * number of output then some number of input descriptors, it's actually two
+ * iovecs, but we pack them into one and note how many of each there were.
+ *
+ * This function returns the descriptor number found, or vq->num (which is
+ * never a valid descriptor number) if none was found. A negative code is
+ * returned on error.
+ *
+ * Stolen from linux-2.6/drivers/vhost/vhost.c.
+ */
+int vring_pop(VirtIODevice *vdev, Vring *vring,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num)
+{
+ struct vring_desc desc;
+ unsigned int i, head, found = 0, num = vring->vr.num;
+ uint16_t avail_idx, last_avail_idx;
+
+ /* If there was a fatal error then refuse operation */
+ if (vring->broken) {
+ return -EFAULT;
+ }
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ last_avail_idx = vring->last_avail_idx;
+ avail_idx = vring->vr.avail->idx;
+
+ if (unlikely((uint16_t)(avail_idx - last_avail_idx) > num)) {
+ error_report("Guest moved used index from %u to %u",
+ last_avail_idx, avail_idx);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ /* If there's nothing new since last we looked. */
+ if (avail_idx == last_avail_idx) {
+ return -EAGAIN;
+ }
+
+ /* Only get avail ring entries after they have been exposed by guest. */
+ smp_rmb();
+
+ /* Grab the next descriptor number they're advertising, and increment
+ * the index we've seen. */
+ head = vring->vr.avail->ring[last_avail_idx % num];
+
+ /* If their number is silly, that's an error. */
+ if (unlikely(head >= num)) {
+ error_report("Guest says index %u > %u is available", head, num);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ if (vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
+ vring_avail_event(&vring->vr) = vring->vr.avail->idx;
+ }
+
+ /* When we start there are none of either input nor output. */
+ *out_num = *in_num = 0;
+
+ i = head;
+ do {
+ if (unlikely(i >= num)) {
+ error_report("Desc index is %u > %u, head = %u", i, num, head);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ if (unlikely(++found > num)) {
+ error_report("Loop detected: last one at %u vq size %u head %u",
+ i, num, head);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ desc = vring->vr.desc[i];
+ if (desc.flags & VRING_DESC_F_INDIRECT) {
+ int ret = get_indirect(vring, iov, iov_end, out_num, in_num, &desc);
+ if (ret < 0) {
+ return ret;
+ }
+ continue;
+ }
+
+ /* If there are not enough iovecs left, stop for now. The caller
+ * should check if there are more descs available once they have dealt
+ * with the current set.
+ */
+ if (iov >= iov_end) {
+ return -ENOBUFS;
+ }
+
+ iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
+ desc.flags & VRING_DESC_F_WRITE);
+ if (!iov->iov_base) {
+ error_report("Failed to map vring desc addr %#" PRIx64 " len %u",
+ (uint64_t)desc.addr, desc.len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ iov->iov_len = desc.len;
+ iov++;
+
+ if (desc.flags & VRING_DESC_F_WRITE) {
+ /* If this is an input descriptor,
+ * increment that count. */
+ *in_num += 1;
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (unlikely(*in_num)) {
+ error_report("Descriptor has out after in: idx %d", i);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ *out_num += 1;
+ }
+ i = desc.next;
+ } while (desc.flags & VRING_DESC_F_NEXT);
+
+ /* On success, increment avail index. */
+ vring->last_avail_idx++;
+ return head;
+}
+
+/* After we've used one of their buffers, we tell them about it.
+ *
+ * Stolen from linux-2.6/drivers/vhost/vhost.c.
+ */
+void vring_push(Vring *vring, unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+ uint16_t new;
+
+ /* Don't touch vring if a fatal error occurred */
+ if (vring->broken) {
+ return;
+ }
+
+ /* The virtqueue contains a ring of used buffers. Get a pointer to the
+ * next entry in that used ring. */
+ used = &vring->vr.used->ring[vring->last_used_idx % vring->vr.num];
+ used->id = head;
+ used->len = len;
+
+ /* Make sure buffer is written before we update index. */
+ smp_wmb();
+
+ new = vring->vr.used->idx = ++vring->last_used_idx;
+ if (unlikely((int16_t)(new - vring->signalled_used) < (uint16_t)1)) {
+ vring->signalled_used_valid = false;
+ }
+}
diff --git a/hw/dataplane/vring.h b/hw/dataplane/vring.h
new file mode 100644
index 0000000..2339b33
--- /dev/null
+++ b/hw/dataplane/vring.h
@@ -0,0 +1,56 @@
+/* Copyright 2012 Red Hat, Inc. and/or its affiliates
+ * Copyright IBM, Corp. 2012
+ *
+ * Based on Linux vhost code:
+ * Copyright (C) 2009 Red Hat, Inc.
+ * Copyright (C) 2006 Rusty Russell IBM Corporation
+ *
+ * Author: Michael S. Tsirkin <mst@redhat.com>
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * Inspiration, some code, and most witty comments come from
+ * Documentation/virtual/lguest/lguest.c, by Rusty Russell
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ */
+
+#ifndef VRING_H
+#define VRING_H
+
+#include <linux/virtio_ring.h>
+#include "qemu-common.h"
+#include "qemu-barrier.h"
+#include "hw/dataplane/hostmem.h"
+#include "hw/virtio.h"
+
+typedef struct {
+ Hostmem hostmem; /* guest memory mapper */
+ struct vring vr; /* virtqueue vring mapped to host memory */
+ uint16_t last_avail_idx; /* last processed avail ring index */
+ uint16_t last_used_idx; /* last processed used ring index */
+ uint16_t signalled_used; /* EVENT_IDX state */
+ bool signalled_used_valid;
+ bool broken; /* was there a fatal error? */
+} Vring;
+
+static inline unsigned int vring_get_num(Vring *vring)
+{
+ return vring->vr.num;
+}
+
+/* Are there more descriptors available? */
+static inline bool vring_more_avail(Vring *vring)
+{
+ return vring->vr.avail->idx != vring->last_avail_idx;
+}
+
+bool vring_setup(Vring *vring, VirtIODevice *vdev, int n);
+void vring_teardown(Vring *vring);
+void vring_set_notification(VirtIODevice *vdev, Vring *vring, bool enable);
+bool vring_should_notify(VirtIODevice *vdev, Vring *vring);
+int vring_pop(VirtIODevice *vdev, Vring *vring,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num);
+void vring_push(Vring *vring, unsigned int head, int len);
+
+#endif /* VRING_H */
diff --git a/trace-events b/trace-events
index 6c6cbf1..a9a791b 100644
--- a/trace-events
+++ b/trace-events
@@ -98,6 +98,9 @@ virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
virtio_blk_handle_write(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
virtio_blk_handle_read(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
+# hw/dataplane/vring.c
+vring_setup(uint64_t physical, void *desc, void *avail, void *used) "vring physical %#"PRIx64" desc %p avail %p used %p"
+
# thread-pool.c
thread_pool_submit(void *req, void *opaque) "req %p opaque %p"
thread_pool_complete(void *req, void *opaque, int ret) "req %p opaque %p ret %d"
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* [Qemu-devel] [PATCH v2 5/8] dataplane: add event loop
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
` (3 preceding siblings ...)
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 4/8] dataplane: add virtqueue vring code Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 6/8] dataplane: add Linux AIO request queue Stefan Hajnoczi
` (2 subsequent siblings)
7 siblings, 0 replies; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
Outside the safety of the global mutex we need to poll on file
descriptors. I found epoll(2) is a convenient way to do that, although
other options could replace this module in the future (such as an
AioContext-based loop or glib's GMainLoop).
One important feature of this small event loop implementation is that
the loop can be terminated in a thread-safe way. This allows QEMU to
stop the data plane thread cleanly.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/dataplane/Makefile.objs | 2 +-
hw/dataplane/event-poll.c | 109 +++++++++++++++++++++++++++++++++++++++++++++
hw/dataplane/event-poll.h | 40 +++++++++++++++++
3 files changed, 150 insertions(+), 1 deletion(-)
create mode 100644 hw/dataplane/event-poll.c
create mode 100644 hw/dataplane/event-poll.h
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
index 34e6d57..e26bd7d 100644
--- a/hw/dataplane/Makefile.objs
+++ b/hw/dataplane/Makefile.objs
@@ -1,3 +1,3 @@
ifeq ($(CONFIG_VIRTIO), y)
-common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o
endif
diff --git a/hw/dataplane/event-poll.c b/hw/dataplane/event-poll.c
new file mode 100644
index 0000000..4a53d48
--- /dev/null
+++ b/hw/dataplane/event-poll.c
@@ -0,0 +1,109 @@
+/*
+ * Event loop with file descriptor polling
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include <sys/epoll.h>
+#include "hw/dataplane/event-poll.h"
+
+/* Add an event notifier and its callback for polling */
+void event_poll_add(EventPoll *poll, EventHandler *handler,
+ EventNotifier *notifier, EventCallback *callback)
+{
+ struct epoll_event event = {
+ .events = EPOLLIN,
+ .data.ptr = handler,
+ };
+ handler->notifier = notifier;
+ handler->callback = callback;
+ if (epoll_ctl(poll->epoll_fd, EPOLL_CTL_ADD,
+ event_notifier_get_fd(notifier), &event) != 0) {
+ fprintf(stderr, "failed to add event handler to epoll: %m\n");
+ exit(1);
+ }
+}
+
+/* Event callback for stopping the event_poll_run() loop */
+static bool handle_stop(EventHandler *handler)
+{
+ return false; /* stop event loop */
+}
+
+void event_poll_init(EventPoll *poll)
+{
+ /* Create epoll file descriptor */
+ poll->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+ if (poll->epoll_fd < 0) {
+ fprintf(stderr, "epoll_create1 failed: %m\n");
+ exit(1);
+ }
+
+ /* Set up stop notifier */
+ if (event_notifier_init(&poll->stop_notifier, 0) < 0) {
+ fprintf(stderr, "failed to init stop notifier\n");
+ exit(1);
+ }
+ event_poll_add(poll, &poll->stop_handler,
+ &poll->stop_notifier, handle_stop);
+}
+
+void event_poll_cleanup(EventPoll *poll)
+{
+ event_notifier_cleanup(&poll->stop_notifier);
+ close(poll->epoll_fd);
+ poll->epoll_fd = -1;
+}
+
+/* Block until the next event and invoke its callback
+ *
+ * Signals must be masked, EINTR should never happen. This is true for QEMU
+ * threads.
+ */
+static bool event_poll(EventPoll *poll)
+{
+ EventHandler *handler;
+ struct epoll_event event;
+ int nevents;
+
+ /* Wait for the next event. Only do one event per call to keep the
+ * function simple, this could be changed later. */
+ nevents = epoll_wait(poll->epoll_fd, &event, 1, -1);
+ if (unlikely(nevents != 1)) {
+ fprintf(stderr, "epoll_wait failed: %m\n");
+ exit(1); /* should never happen */
+ }
+
+ /* Find out which event handler has become active */
+ handler = event.data.ptr;
+
+ /* Clear the eventfd */
+ event_notifier_test_and_clear(handler->notifier);
+
+ /* Handle the event */
+ return handler->callback(handler);
+}
+
+void event_poll_run(EventPoll *poll)
+{
+ while (event_poll(poll)) {
+ /* do nothing */
+ }
+}
+
+/* Stop the event_poll_run() loop
+ *
+ * This function can be used from another thread.
+ */
+void event_poll_stop(EventPoll *poll)
+{
+ event_notifier_set(&poll->stop_notifier);
+}
diff --git a/hw/dataplane/event-poll.h b/hw/dataplane/event-poll.h
new file mode 100644
index 0000000..5e1771f
--- /dev/null
+++ b/hw/dataplane/event-poll.h
@@ -0,0 +1,40 @@
+/*
+ * Event loop with file descriptor polling
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef EVENT_POLL_H
+#define EVENT_POLL_H
+
+#include "event_notifier.h"
+
+typedef struct EventHandler EventHandler;
+typedef bool EventCallback(EventHandler *handler);
+struct EventHandler {
+ EventNotifier *notifier; /* eventfd */
+ EventCallback *callback; /* callback function */
+};
+
+typedef struct {
+ int epoll_fd; /* epoll(2) file descriptor */
+ EventNotifier stop_notifier; /* stop poll notifier */
+ EventHandler stop_handler; /* stop poll handler */
+} EventPoll;
+
+void event_poll_add(EventPoll *poll, EventHandler *handler,
+ EventNotifier *notifier, EventCallback *callback);
+void event_poll_init(EventPoll *poll);
+void event_poll_cleanup(EventPoll *poll);
+void event_poll_run(EventPoll *poll);
+void event_poll_stop(EventPoll *poll);
+
+#endif /* EVENT_POLL_H */
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* [Qemu-devel] [PATCH v2 6/8] dataplane: add Linux AIO request queue
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
` (4 preceding siblings ...)
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 5/8] dataplane: add event loop Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code Stefan Hajnoczi
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature Stefan Hajnoczi
7 siblings, 0 replies; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The IOQueue has a pool of iocb structs and a function to add new
read/write requests. Multiple requests can be added before calling the
submit function to actually tell the host kernel to begin I/O. This
allows callers to batch requests and submit them in one go.
The actual I/O is performed using Linux AIO.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/dataplane/Makefile.objs | 2 +-
hw/dataplane/ioq.c | 118 +++++++++++++++++++++++++++++++++++++++++++++
hw/dataplane/ioq.h | 57 ++++++++++++++++++++++
3 files changed, 176 insertions(+), 1 deletion(-)
create mode 100644 hw/dataplane/ioq.c
create mode 100644 hw/dataplane/ioq.h
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
index e26bd7d..abd408f 100644
--- a/hw/dataplane/Makefile.objs
+++ b/hw/dataplane/Makefile.objs
@@ -1,3 +1,3 @@
ifeq ($(CONFIG_VIRTIO), y)
-common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o
endif
diff --git a/hw/dataplane/ioq.c b/hw/dataplane/ioq.c
new file mode 100644
index 0000000..7adeb5d
--- /dev/null
+++ b/hw/dataplane/ioq.c
@@ -0,0 +1,118 @@
+/*
+ * Linux AIO request queue
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "hw/dataplane/ioq.h"
+
+void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs)
+{
+ int rc;
+
+ ioq->fd = fd;
+ ioq->max_reqs = max_reqs;
+
+ memset(&ioq->io_ctx, 0, sizeof ioq->io_ctx);
+ rc = io_setup(max_reqs, &ioq->io_ctx);
+ if (rc != 0) {
+ fprintf(stderr, "ioq io_setup failed %d\n", rc);
+ exit(1);
+ }
+
+ rc = event_notifier_init(&ioq->io_notifier, 0);
+ if (rc != 0) {
+ fprintf(stderr, "ioq io event notifier creation failed %d\n", rc);
+ exit(1);
+ }
+
+ ioq->freelist = g_malloc0(sizeof ioq->freelist[0] * max_reqs);
+ ioq->freelist_idx = 0;
+
+ ioq->queue = g_malloc0(sizeof ioq->queue[0] * max_reqs);
+ ioq->queue_idx = 0;
+}
+
+void ioq_cleanup(IOQueue *ioq)
+{
+ g_free(ioq->freelist);
+ g_free(ioq->queue);
+
+ event_notifier_cleanup(&ioq->io_notifier);
+ io_destroy(ioq->io_ctx);
+}
+
+EventNotifier *ioq_get_notifier(IOQueue *ioq)
+{
+ return &ioq->io_notifier;
+}
+
+struct iocb *ioq_get_iocb(IOQueue *ioq)
+{
+ if (unlikely(ioq->freelist_idx == 0)) {
+ fprintf(stderr, "ioq underflow\n");
+ exit(1);
+ }
+ struct iocb *iocb = ioq->freelist[--ioq->freelist_idx];
+ ioq->queue[ioq->queue_idx++] = iocb;
+ return iocb;
+}
+
+void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb)
+{
+ if (unlikely(ioq->freelist_idx == ioq->max_reqs)) {
+ fprintf(stderr, "ioq overflow\n");
+ exit(1);
+ }
+ ioq->freelist[ioq->freelist_idx++] = iocb;
+}
+
+struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
+ unsigned int count, long long offset)
+{
+ struct iocb *iocb = ioq_get_iocb(ioq);
+
+ if (read) {
+ io_prep_preadv(iocb, ioq->fd, iov, count, offset);
+ } else {
+ io_prep_pwritev(iocb, ioq->fd, iov, count, offset);
+ }
+ io_set_eventfd(iocb, event_notifier_get_fd(&ioq->io_notifier));
+ return iocb;
+}
+
+int ioq_submit(IOQueue *ioq)
+{
+ int rc = io_submit(ioq->io_ctx, ioq->queue_idx, ioq->queue);
+ ioq->queue_idx = 0; /* reset */
+ return rc;
+}
+
+int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
+ void *opaque)
+{
+ struct io_event events[ioq->max_reqs];
+ int nevents, i;
+
+ nevents = io_getevents(ioq->io_ctx, 0, ioq->max_reqs, events, NULL);
+ if (unlikely(nevents < 0)) {
+ fprintf(stderr, "io_getevents failed %d\n", nevents);
+ exit(1);
+ }
+
+ for (i = 0; i < nevents; i++) {
+ ssize_t ret = ((uint64_t)events[i].res2 << 32) | events[i].res;
+
+ completion(events[i].obj, ret, opaque);
+ ioq_put_iocb(ioq, events[i].obj);
+ }
+ return nevents;
+}
diff --git a/hw/dataplane/ioq.h b/hw/dataplane/ioq.h
new file mode 100644
index 0000000..890db22
--- /dev/null
+++ b/hw/dataplane/ioq.h
@@ -0,0 +1,57 @@
+/*
+ * Linux AIO request queue
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef IOQ_H
+#define IOQ_H
+
+#include <libaio.h>
+#include "event_notifier.h"
+
+typedef struct {
+ int fd; /* file descriptor */
+ unsigned int max_reqs; /* max length of freelist and queue */
+
+ io_context_t io_ctx; /* Linux AIO context */
+ EventNotifier io_notifier; /* Linux AIO eventfd */
+
+ /* Requests can complete in any order so a free list is necessary to manage
+ * available iocbs.
+ */
+ struct iocb **freelist; /* free iocbs */
+ unsigned int freelist_idx;
+
+ /* Multiple requests are queued up before submitting them all in one go */
+ struct iocb **queue; /* queued iocbs */
+ unsigned int queue_idx;
+} IOQueue;
+
+void ioq_init(IOQueue *ioq, int fd, unsigned int max_reqs);
+void ioq_cleanup(IOQueue *ioq);
+EventNotifier *ioq_get_notifier(IOQueue *ioq);
+struct iocb *ioq_get_iocb(IOQueue *ioq);
+void ioq_put_iocb(IOQueue *ioq, struct iocb *iocb);
+struct iocb *ioq_rdwr(IOQueue *ioq, bool read, struct iovec *iov,
+ unsigned int count, long long offset);
+int ioq_submit(IOQueue *ioq);
+
+static inline unsigned int ioq_num_queued(IOQueue *ioq)
+{
+ return ioq->queue_idx;
+}
+
+typedef void IOQueueCompletion(struct iocb *iocb, ssize_t ret, void *opaque);
+int ioq_run_completion(IOQueue *ioq, IOQueueCompletion *completion,
+ void *opaque);
+
+#endif /* IOQ_H */
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
` (5 preceding siblings ...)
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 6/8] dataplane: add Linux AIO request queue Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 13:04 ` Michael S. Tsirkin
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature Stefan Hajnoczi
7 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
virtio-blk-data-plane is a subset implementation of virtio-blk. It only
handles read, write, and flush requests. It does this using a dedicated
thread that executes an epoll(2)-based event loop and processes I/O
using Linux AIO.
This approach performs very well but can be used for raw image files
only. The number of IOPS achieved has been reported to be several times
higher than the existing virtio-blk implementation.
Eventually it should be possible to unify virtio-blk-data-plane with the
main body of QEMU code once the block layer and hardware emulation is
able to run outside the global mutex.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/dataplane/Makefile.objs | 2 +-
hw/dataplane/virtio-blk.c | 418 +++++++++++++++++++++++++++++++++++++++++++++
hw/dataplane/virtio-blk.h | 41 +++++
trace-events | 6 +
4 files changed, 466 insertions(+), 1 deletion(-)
create mode 100644 hw/dataplane/virtio-blk.c
create mode 100644 hw/dataplane/virtio-blk.h
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
index abd408f..682aa9e 100644
--- a/hw/dataplane/Makefile.objs
+++ b/hw/dataplane/Makefile.objs
@@ -1,3 +1,3 @@
ifeq ($(CONFIG_VIRTIO), y)
-common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o virtio-blk.o
endif
diff --git a/hw/dataplane/virtio-blk.c b/hw/dataplane/virtio-blk.c
new file mode 100644
index 0000000..5dcc872
--- /dev/null
+++ b/hw/dataplane/virtio-blk.c
@@ -0,0 +1,418 @@
+/*
+ * Dedicated thread for virtio-blk I/O processing
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "trace.h"
+#include "event-poll.h"
+#include "qemu-thread.h"
+#include "vring.h"
+#include "ioq.h"
+#include "hw/virtio-blk.h"
+#include "hw/dataplane/virtio-blk.h"
+
+enum {
+ SEG_MAX = 126, /* maximum number of I/O segments */
+ VRING_MAX = SEG_MAX + 2, /* maximum number of vring descriptors */
+ REQ_MAX = VRING_MAX, /* maximum number of requests in the vring,
+ * is VRING_MAX / 2 with traditional and
+ * VRING_MAX with indirect descriptors */
+};
+
+typedef struct {
+ struct iocb iocb; /* Linux AIO control block */
+ unsigned char *status; /* virtio block status code */
+ unsigned int head; /* vring descriptor index */
+} VirtIOBlockRequest;
+
+struct VirtIOBlockDataPlane {
+ bool started;
+ QEMUBH *start_bh;
+ QemuThread thread;
+
+ int fd; /* image file descriptor */
+
+ VirtIODevice *vdev;
+ Vring vring; /* virtqueue vring */
+ EventNotifier *guest_notifier; /* irq */
+
+ EventPoll event_poll; /* event poller */
+ EventHandler io_handler; /* Linux AIO completion handler */
+ EventHandler notify_handler; /* virtqueue notify handler */
+
+ IOQueue ioqueue; /* Linux AIO queue (should really be per
+ dataplane thread) */
+ VirtIOBlockRequest requests[REQ_MAX]; /* pool of requests, managed by the
+ queue */
+
+ unsigned int num_reqs;
+ QemuMutex num_reqs_lock;
+ QemuCond no_reqs_cond;
+};
+
+/* Raise an interrupt to signal guest, if necessary */
+static void notify_guest(VirtIOBlockDataPlane *s)
+{
+ if (!vring_should_notify(s->vdev, &s->vring)) {
+ return;
+ }
+
+ event_notifier_set(s->guest_notifier);
+}
+
+static void complete_request(struct iocb *iocb, ssize_t ret, void *opaque)
+{
+ VirtIOBlockDataPlane *s = opaque;
+ VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
+ int len;
+
+ if (likely(ret >= 0)) {
+ *req->status = VIRTIO_BLK_S_OK;
+ len = ret;
+ } else {
+ *req->status = VIRTIO_BLK_S_IOERR;
+ len = 0;
+ }
+
+ trace_virtio_blk_data_plane_complete_request(s, req->head, ret);
+
+ /* According to the virtio specification len should be the number of bytes
+ * written to, but for virtio-blk it seems to be the number of bytes
+ * transferred plus the status bytes.
+ */
+ vring_push(&s->vring, req->head, len + sizeof(*req->status));
+
+ qemu_mutex_lock(&s->num_reqs_lock);
+ if (--s->num_reqs == 0) {
+ qemu_cond_broadcast(&s->no_reqs_cond);
+ }
+ qemu_mutex_unlock(&s->num_reqs_lock);
+}
+
+static void process_request(IOQueue *ioq, struct iovec iov[],
+ unsigned int out_num, unsigned int in_num,
+ unsigned int head)
+{
+ /* Virtio block requests look like this: */
+ struct virtio_blk_outhdr *outhdr; /* iov[0] */
+ /* data[] ... */
+ struct virtio_blk_inhdr *inhdr; /* iov[out_num + in_num - 1] */
+
+ if (unlikely(out_num == 0 || in_num == 0 ||
+ iov[0].iov_len != sizeof *outhdr ||
+ iov[out_num + in_num - 1].iov_len != sizeof *inhdr)) {
+ fprintf(stderr, "virtio-blk invalid request\n");
+ exit(1);
+ }
+
+ outhdr = iov[0].iov_base;
+ inhdr = iov[out_num + in_num - 1].iov_base;
+
+ /* TODO Linux sets the barrier bit even when not advertised! */
+ uint32_t type = outhdr->type & ~VIRTIO_BLK_T_BARRIER;
+ struct iocb *iocb;
+ switch (type & (VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_SCSI_CMD |
+ VIRTIO_BLK_T_FLUSH)) {
+ case VIRTIO_BLK_T_IN:
+ if (unlikely(out_num != 1)) {
+ fprintf(stderr, "virtio-blk invalid read request\n");
+ exit(1);
+ }
+ iocb = ioq_rdwr(ioq, true, &iov[1], in_num - 1, outhdr->sector * 512);
+ break;
+
+ case VIRTIO_BLK_T_OUT:
+ if (unlikely(in_num != 1)) {
+ fprintf(stderr, "virtio-blk invalid write request\n");
+ exit(1);
+ }
+ iocb = ioq_rdwr(ioq, false, &iov[1], out_num - 1, outhdr->sector * 512);
+ break;
+
+ case VIRTIO_BLK_T_SCSI_CMD:
+ if (unlikely(in_num == 0)) {
+ fprintf(stderr, "virtio-blk invalid SCSI command request\n");
+ exit(1);
+ }
+
+ /* TODO support SCSI commands */
+ {
+ VirtIOBlockDataPlane *s = container_of(ioq, VirtIOBlockDataPlane,
+ ioqueue);
+ inhdr->status = VIRTIO_BLK_S_UNSUPP;
+ vring_push(&s->vring, head, sizeof *inhdr);
+ notify_guest(s);
+ }
+ return;
+
+ case VIRTIO_BLK_T_FLUSH:
+ if (unlikely(in_num != 1 || out_num != 1)) {
+ fprintf(stderr, "virtio-blk invalid flush request\n");
+ exit(1);
+ }
+
+ /* TODO fdsync not supported by Linux AIO, do it synchronously here! */
+ {
+ VirtIOBlockDataPlane *s = container_of(ioq, VirtIOBlockDataPlane,
+ ioqueue);
+ fdatasync(s->fd);
+ inhdr->status = VIRTIO_BLK_S_OK;
+ vring_push(&s->vring, head, sizeof *inhdr);
+ notify_guest(s);
+ }
+ return;
+
+ default:
+ fprintf(stderr, "virtio-blk unsupported request type %#x\n",
+ outhdr->type);
+ exit(1);
+ }
+
+ /* Fill in virtio block metadata needed for completion */
+ VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
+ req->head = head;
+ req->status = &inhdr->status;
+}
+
+static bool handle_notify(EventHandler *handler)
+{
+ VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
+ notify_handler);
+
+ /* There is one array of iovecs into which all new requests are extracted
+ * from the vring. Requests are read from the vring and the translated
+ * descriptors are written to the iovecs array. The iovecs do not have to
+ * persist across handle_notify() calls because the kernel copies the
+ * iovecs on io_submit().
+ *
+ * Handling io_submit() EAGAIN may require storing the requests across
+ * handle_notify() calls until the kernel has sufficient resources to
+ * accept more I/O. This is not implemented yet.
+ */
+ struct iovec iovec[VRING_MAX];
+ struct iovec *end = &iovec[VRING_MAX];
+ struct iovec *iov = iovec;
+
+ /* When a request is read from the vring, the index of the first descriptor
+ * (aka head) is returned so that the completed request can be pushed onto
+ * the vring later.
+ *
+ * The number of hypervisor read-only iovecs is out_num. The number of
+ * hypervisor write-only iovecs is in_num.
+ */
+ int head;
+ unsigned int out_num = 0, in_num = 0;
+ unsigned int num_queued;
+
+ for (;;) {
+ /* Disable guest->host notifies to avoid unnecessary vmexits */
+ vring_set_notification(s->vdev, &s->vring, false);
+
+ for (;;) {
+ head = vring_pop(s->vdev, &s->vring, iov, end, &out_num, &in_num);
+ if (head < 0) {
+ break; /* no more requests */
+ }
+
+ trace_virtio_blk_data_plane_process_request(s, out_num, in_num,
+ head);
+
+ process_request(&s->ioqueue, iov, out_num, in_num, head);
+ iov += out_num + in_num;
+ }
+
+ if (likely(head == -EAGAIN)) { /* vring emptied */
+ /* Re-enable guest->host notifies and stop processing the vring.
+ * But if the guest has snuck in more descriptors, keep processing.
+ */
+ vring_set_notification(s->vdev, &s->vring, true);
+ smp_mb();
+ if (!vring_more_avail(&s->vring)) {
+ break;
+ }
+ } else { /* head == -ENOBUFS or fatal error, iovecs[] is depleted */
+ /* Since there are no iovecs[] left, stop processing for now. Do
+ * not re-enable guest->host notifies since the I/O completion
+ * handler knows to check for more vring descriptors anyway.
+ */
+ break;
+ }
+ }
+
+ num_queued = ioq_num_queued(&s->ioqueue);
+ if (num_queued > 0) {
+ qemu_mutex_lock(&s->num_reqs_lock);
+ s->num_reqs += num_queued;
+ qemu_mutex_unlock(&s->num_reqs_lock);
+
+ int rc = ioq_submit(&s->ioqueue);
+ if (unlikely(rc < 0)) {
+ fprintf(stderr, "ioq_submit failed %d\n", rc);
+ exit(1);
+ }
+ }
+ return true;
+}
+
+static bool handle_io(EventHandler *handler)
+{
+ VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
+ io_handler);
+
+ if (ioq_run_completion(&s->ioqueue, complete_request, s) > 0) {
+ notify_guest(s);
+ }
+
+ /* If there were more requests than iovecs, the vring will not be empty yet
+ * so check again. There should now be enough resources to process more
+ * requests.
+ */
+ if (unlikely(vring_more_avail(&s->vring))) {
+ return handle_notify(&s->notify_handler);
+ }
+
+ return true;
+}
+
+static void *data_plane_thread(void *opaque)
+{
+ VirtIOBlockDataPlane *s = opaque;
+ event_poll_run(&s->event_poll);
+ return NULL;
+}
+
+static void start_data_plane_bh(void *opaque)
+{
+ VirtIOBlockDataPlane *s = opaque;
+
+ qemu_bh_delete(s->start_bh);
+ s->start_bh = NULL;
+ qemu_thread_create(&s->thread, data_plane_thread,
+ s, QEMU_THREAD_JOINABLE);
+}
+
+VirtIOBlockDataPlane *virtio_blk_data_plane_create(VirtIODevice *vdev, int fd)
+{
+ VirtIOBlockDataPlane *s;
+
+ s = g_new0(VirtIOBlockDataPlane, 1);
+ s->vdev = vdev;
+ s->fd = fd;
+ return s;
+}
+
+void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
+{
+ if (!s) {
+ return;
+ }
+ virtio_blk_data_plane_stop(s);
+ g_free(s);
+}
+
+/* Block until pending requests have completed
+ *
+ * The vring continues to be serviced so ensure no new requests will be added
+ * to avoid races.
+ */
+void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s)
+{
+ qemu_mutex_lock(&s->num_reqs_lock);
+ while (s->num_reqs > 0) {
+ qemu_cond_wait(&s->no_reqs_cond, &s->num_reqs_lock);
+ }
+ qemu_mutex_unlock(&s->num_reqs_lock);
+}
+
+void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
+{
+ VirtQueue *vq;
+ int i;
+
+ if (s->started) {
+ return;
+ }
+
+ vq = virtio_get_queue(s->vdev, 0);
+ if (!vring_setup(&s->vring, s->vdev, 0)) {
+ return;
+ }
+
+ event_poll_init(&s->event_poll);
+
+ /* Set up guest notifier (irq) */
+ if (s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque,
+ true) != 0) {
+ fprintf(stderr, "virtio-blk failed to set guest notifier, "
+ "ensure -enable-kvm is set\n");
+ exit(1);
+ }
+ s->guest_notifier = virtio_queue_get_guest_notifier(vq);
+
+ /* Set up virtqueue notify */
+ if (s->vdev->binding->set_host_notifier(s->vdev->binding_opaque,
+ 0, true) != 0) {
+ fprintf(stderr, "virtio-blk failed to set host notifier\n");
+ exit(1);
+ }
+ event_poll_add(&s->event_poll, &s->notify_handler,
+ virtio_queue_get_host_notifier(vq),
+ handle_notify);
+
+ /* Set up ioqueue */
+ ioq_init(&s->ioqueue, s->fd, REQ_MAX);
+ for (i = 0; i < ARRAY_SIZE(s->requests); i++) {
+ ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
+ }
+ event_poll_add(&s->event_poll, &s->io_handler,
+ ioq_get_notifier(&s->ioqueue), handle_io);
+
+ s->started = true;
+ trace_virtio_blk_data_plane_start(s);
+
+ /* Kick right away to begin processing requests already in vring */
+ event_notifier_set(virtio_queue_get_host_notifier(vq));
+
+ /* Spawn thread in BH so it inherits iothread cpusets */
+ s->start_bh = qemu_bh_new(start_data_plane_bh, s);
+ qemu_bh_schedule(s->start_bh);
+}
+
+void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
+{
+ if (!s->started) {
+ return;
+ }
+ s->started = false;
+ trace_virtio_blk_data_plane_stop(s);
+
+ /* Stop thread or cancel pending thread creation BH */
+ if (s->start_bh) {
+ qemu_bh_delete(s->start_bh);
+ s->start_bh = NULL;
+ } else {
+ virtio_blk_data_plane_drain(s);
+ event_poll_stop(&s->event_poll);
+ qemu_thread_join(&s->thread);
+ }
+
+ ioq_cleanup(&s->ioqueue);
+
+ s->vdev->binding->set_host_notifier(s->vdev->binding_opaque, 0, false);
+
+ event_poll_cleanup(&s->event_poll);
+
+ /* Clean up guest notifier (irq) */
+ s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque, false);
+
+ vring_teardown(&s->vring);
+}
diff --git a/hw/dataplane/virtio-blk.h b/hw/dataplane/virtio-blk.h
new file mode 100644
index 0000000..ddf1115
--- /dev/null
+++ b/hw/dataplane/virtio-blk.h
@@ -0,0 +1,41 @@
+/*
+ * Dedicated thread for virtio-blk I/O processing
+ *
+ * Copyright 2012 IBM, Corp.
+ * Copyright 2012 Red Hat, Inc. and/or its affiliates
+ *
+ * Authors:
+ * Stefan Hajnoczi <stefanha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef HW_DATAPLANE_VIRTIO_BLK_H
+#define HW_DATAPLANE_VIRTIO_BLK_H
+
+#include "hw/virtio.h"
+
+typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
+
+#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
+VirtIOBlockDataPlane *virtio_blk_data_plane_create(VirtIODevice *vdev, int fd);
+void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);
+void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s);
+#else
+static inline VirtIOBlockDataPlane *virtio_blk_data_plane_create(
+ VirtIODevice *vdev, int fd)
+{
+ return NULL;
+}
+
+static inline void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) {}
+static inline void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) {}
+static inline void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s) {}
+static inline void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s) {}
+#endif
+
+#endif /* HW_DATAPLANE_VIRTIO_BLK_H */
diff --git a/trace-events b/trace-events
index a9a791b..1edc2ae 100644
--- a/trace-events
+++ b/trace-events
@@ -98,6 +98,12 @@ virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
virtio_blk_handle_write(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
virtio_blk_handle_read(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
+# hw/dataplane/virtio-blk.c
+virtio_blk_data_plane_start(void *s) "dataplane %p"
+virtio_blk_data_plane_stop(void *s) "dataplane %p"
+virtio_blk_data_plane_process_request(void *s, unsigned int out_num, unsigned int in_num, unsigned int head) "dataplane %p out_num %u in_num %u head %u"
+virtio_blk_data_plane_complete_request(void *s, unsigned int head, int ret) "dataplane %p head %u ret %d"
+
# hw/dataplane/vring.c
vring_setup(uint64_t physical, void *desc, void *avail, void *used) "vring physical %#"PRIx64" desc %p avail %p used %p"
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code Stefan Hajnoczi
@ 2012-11-20 13:04 ` Michael S. Tsirkin
2012-11-20 13:54 ` Stefan Hajnoczi
0 siblings, 1 reply; 21+ messages in thread
From: Michael S. Tsirkin @ 2012-11-20 13:04 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, rusty, qemu-devel, khoa,
Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 01:31:51PM +0100, Stefan Hajnoczi wrote:
> virtio-blk-data-plane is a subset implementation of virtio-blk. It only
> handles read, write, and flush requests. It does this using a dedicated
> thread that executes an epoll(2)-based event loop and processes I/O
> using Linux AIO.
>
> This approach performs very well but can be used for raw image files
> only. The number of IOPS achieved has been reported to be several times
> higher than the existing virtio-blk implementation.
>
> Eventually it should be possible to unify virtio-blk-data-plane with the
> main body of QEMU code once the block layer and hardware emulation is
> able to run outside the global mutex.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/dataplane/Makefile.objs | 2 +-
> hw/dataplane/virtio-blk.c | 418 +++++++++++++++++++++++++++++++++++++++++++++
> hw/dataplane/virtio-blk.h | 41 +++++
> trace-events | 6 +
> 4 files changed, 466 insertions(+), 1 deletion(-)
> create mode 100644 hw/dataplane/virtio-blk.c
> create mode 100644 hw/dataplane/virtio-blk.h
>
> diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
> index abd408f..682aa9e 100644
> --- a/hw/dataplane/Makefile.objs
> +++ b/hw/dataplane/Makefile.objs
> @@ -1,3 +1,3 @@
> ifeq ($(CONFIG_VIRTIO), y)
> -common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o
> +common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o event-poll.o ioq.o virtio-blk.o
> endif
> diff --git a/hw/dataplane/virtio-blk.c b/hw/dataplane/virtio-blk.c
> new file mode 100644
> index 0000000..5dcc872
> --- /dev/null
> +++ b/hw/dataplane/virtio-blk.c
> @@ -0,0 +1,418 @@
> +/*
> + * Dedicated thread for virtio-blk I/O processing
> + *
> + * Copyright 2012 IBM, Corp.
> + * Copyright 2012 Red Hat, Inc. and/or its affiliates
> + *
> + * Authors:
> + * Stefan Hajnoczi <stefanha@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#include "trace.h"
> +#include "event-poll.h"
> +#include "qemu-thread.h"
> +#include "vring.h"
> +#include "ioq.h"
> +#include "hw/virtio-blk.h"
> +#include "hw/dataplane/virtio-blk.h"
> +
> +enum {
> + SEG_MAX = 126, /* maximum number of I/O segments */
> + VRING_MAX = SEG_MAX + 2, /* maximum number of vring descriptors */
> + REQ_MAX = VRING_MAX, /* maximum number of requests in the vring,
> + * is VRING_MAX / 2 with traditional and
> + * VRING_MAX with indirect descriptors */
> +};
> +
> +typedef struct {
> + struct iocb iocb; /* Linux AIO control block */
> + unsigned char *status; /* virtio block status code */
> + unsigned int head; /* vring descriptor index */
> +} VirtIOBlockRequest;
> +
> +struct VirtIOBlockDataPlane {
> + bool started;
> + QEMUBH *start_bh;
> + QemuThread thread;
> +
> + int fd; /* image file descriptor */
> +
> + VirtIODevice *vdev;
> + Vring vring; /* virtqueue vring */
> + EventNotifier *guest_notifier; /* irq */
> +
> + EventPoll event_poll; /* event poller */
> + EventHandler io_handler; /* Linux AIO completion handler */
> + EventHandler notify_handler; /* virtqueue notify handler */
> +
> + IOQueue ioqueue; /* Linux AIO queue (should really be per
> + dataplane thread) */
> + VirtIOBlockRequest requests[REQ_MAX]; /* pool of requests, managed by the
> + queue */
> +
> + unsigned int num_reqs;
> + QemuMutex num_reqs_lock;
> + QemuCond no_reqs_cond;
> +};
> +
> +/* Raise an interrupt to signal guest, if necessary */
> +static void notify_guest(VirtIOBlockDataPlane *s)
> +{
> + if (!vring_should_notify(s->vdev, &s->vring)) {
> + return;
> + }
> +
> + event_notifier_set(s->guest_notifier);
> +}
> +
> +static void complete_request(struct iocb *iocb, ssize_t ret, void *opaque)
> +{
> + VirtIOBlockDataPlane *s = opaque;
> + VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
> + int len;
> +
> + if (likely(ret >= 0)) {
> + *req->status = VIRTIO_BLK_S_OK;
> + len = ret;
> + } else {
> + *req->status = VIRTIO_BLK_S_IOERR;
> + len = 0;
> + }
> +
> + trace_virtio_blk_data_plane_complete_request(s, req->head, ret);
> +
> + /* According to the virtio specification len should be the number of bytes
> + * written to, but for virtio-blk it seems to be the number of bytes
> + * transferred plus the status bytes.
> + */
> + vring_push(&s->vring, req->head, len + sizeof(*req->status));
> +
> + qemu_mutex_lock(&s->num_reqs_lock);
> + if (--s->num_reqs == 0) {
> + qemu_cond_broadcast(&s->no_reqs_cond);
> + }
> + qemu_mutex_unlock(&s->num_reqs_lock);
> +}
> +
> +static void process_request(IOQueue *ioq, struct iovec iov[],
> + unsigned int out_num, unsigned int in_num,
> + unsigned int head)
> +{
> + /* Virtio block requests look like this: */
> + struct virtio_blk_outhdr *outhdr; /* iov[0] */
> + /* data[] ... */
> + struct virtio_blk_inhdr *inhdr; /* iov[out_num + in_num - 1] */
> +
> + if (unlikely(out_num == 0 || in_num == 0 ||
> + iov[0].iov_len != sizeof *outhdr ||
> + iov[out_num + in_num - 1].iov_len != sizeof *inhdr)) {
> + fprintf(stderr, "virtio-blk invalid request\n");
> + exit(1);
> + }
> +
> + outhdr = iov[0].iov_base;
> + inhdr = iov[out_num + in_num - 1].iov_base;
> +
Rusty is trying to get rid of hard-coded layout assumptions,
let's not add any more if we can help it.
> + /* TODO Linux sets the barrier bit even when not advertised! */
> + uint32_t type = outhdr->type & ~VIRTIO_BLK_T_BARRIER;
> + struct iocb *iocb;
> + switch (type & (VIRTIO_BLK_T_OUT | VIRTIO_BLK_T_SCSI_CMD |
> + VIRTIO_BLK_T_FLUSH)) {
> + case VIRTIO_BLK_T_IN:
> + if (unlikely(out_num != 1)) {
> + fprintf(stderr, "virtio-blk invalid read request\n");
> + exit(1);
> + }
> + iocb = ioq_rdwr(ioq, true, &iov[1], in_num - 1, outhdr->sector * 512);
> + break;
> +
> + case VIRTIO_BLK_T_OUT:
> + if (unlikely(in_num != 1)) {
> + fprintf(stderr, "virtio-blk invalid write request\n");
> + exit(1);
> + }
> + iocb = ioq_rdwr(ioq, false, &iov[1], out_num - 1, outhdr->sector * 512);
> + break;
> +
> + case VIRTIO_BLK_T_SCSI_CMD:
> + if (unlikely(in_num == 0)) {
> + fprintf(stderr, "virtio-blk invalid SCSI command request\n");
> + exit(1);
> + }
> +
> + /* TODO support SCSI commands */
> + {
> + VirtIOBlockDataPlane *s = container_of(ioq, VirtIOBlockDataPlane,
> + ioqueue);
> + inhdr->status = VIRTIO_BLK_S_UNSUPP;
> + vring_push(&s->vring, head, sizeof *inhdr);
> + notify_guest(s);
> + }
> + return;
> +
> + case VIRTIO_BLK_T_FLUSH:
> + if (unlikely(in_num != 1 || out_num != 1)) {
> + fprintf(stderr, "virtio-blk invalid flush request\n");
> + exit(1);
> + }
> +
> + /* TODO fdsync not supported by Linux AIO, do it synchronously here! */
> + {
> + VirtIOBlockDataPlane *s = container_of(ioq, VirtIOBlockDataPlane,
> + ioqueue);
> + fdatasync(s->fd);
> + inhdr->status = VIRTIO_BLK_S_OK;
> + vring_push(&s->vring, head, sizeof *inhdr);
> + notify_guest(s);
> + }
> + return;
> +
> + default:
> + fprintf(stderr, "virtio-blk unsupported request type %#x\n",
> + outhdr->type);
> + exit(1);
> + }
> +
> + /* Fill in virtio block metadata needed for completion */
> + VirtIOBlockRequest *req = container_of(iocb, VirtIOBlockRequest, iocb);
> + req->head = head;
> + req->status = &inhdr->status;
> +}
> +
> +static bool handle_notify(EventHandler *handler)
> +{
> + VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
> + notify_handler);
> +
> + /* There is one array of iovecs into which all new requests are extracted
> + * from the vring. Requests are read from the vring and the translated
> + * descriptors are written to the iovecs array. The iovecs do not have to
> + * persist across handle_notify() calls because the kernel copies the
> + * iovecs on io_submit().
> + *
> + * Handling io_submit() EAGAIN may require storing the requests across
> + * handle_notify() calls until the kernel has sufficient resources to
> + * accept more I/O. This is not implemented yet.
> + */
> + struct iovec iovec[VRING_MAX];
> + struct iovec *end = &iovec[VRING_MAX];
> + struct iovec *iov = iovec;
> +
> + /* When a request is read from the vring, the index of the first descriptor
> + * (aka head) is returned so that the completed request can be pushed onto
> + * the vring later.
> + *
> + * The number of hypervisor read-only iovecs is out_num. The number of
> + * hypervisor write-only iovecs is in_num.
> + */
> + int head;
> + unsigned int out_num = 0, in_num = 0;
> + unsigned int num_queued;
> +
> + for (;;) {
> + /* Disable guest->host notifies to avoid unnecessary vmexits */
> + vring_set_notification(s->vdev, &s->vring, false);
> +
> + for (;;) {
> + head = vring_pop(s->vdev, &s->vring, iov, end, &out_num, &in_num);
> + if (head < 0) {
> + break; /* no more requests */
> + }
> +
> + trace_virtio_blk_data_plane_process_request(s, out_num, in_num,
> + head);
> +
> + process_request(&s->ioqueue, iov, out_num, in_num, head);
> + iov += out_num + in_num;
> + }
> +
> + if (likely(head == -EAGAIN)) { /* vring emptied */
> + /* Re-enable guest->host notifies and stop processing the vring.
> + * But if the guest has snuck in more descriptors, keep processing.
> + */
> + vring_set_notification(s->vdev, &s->vring, true);
> + smp_mb();
> + if (!vring_more_avail(&s->vring)) {
> + break;
> + }
> + } else { /* head == -ENOBUFS or fatal error, iovecs[] is depleted */
> + /* Since there are no iovecs[] left, stop processing for now. Do
> + * not re-enable guest->host notifies since the I/O completion
> + * handler knows to check for more vring descriptors anyway.
> + */
> + break;
> + }
> + }
> +
> + num_queued = ioq_num_queued(&s->ioqueue);
> + if (num_queued > 0) {
> + qemu_mutex_lock(&s->num_reqs_lock);
> + s->num_reqs += num_queued;
> + qemu_mutex_unlock(&s->num_reqs_lock);
> +
> + int rc = ioq_submit(&s->ioqueue);
> + if (unlikely(rc < 0)) {
> + fprintf(stderr, "ioq_submit failed %d\n", rc);
> + exit(1);
> + }
> + }
> + return true;
> +}
> +
> +static bool handle_io(EventHandler *handler)
> +{
> + VirtIOBlockDataPlane *s = container_of(handler, VirtIOBlockDataPlane,
> + io_handler);
> +
> + if (ioq_run_completion(&s->ioqueue, complete_request, s) > 0) {
> + notify_guest(s);
> + }
> +
> + /* If there were more requests than iovecs, the vring will not be empty yet
> + * so check again. There should now be enough resources to process more
> + * requests.
> + */
> + if (unlikely(vring_more_avail(&s->vring))) {
> + return handle_notify(&s->notify_handler);
> + }
> +
> + return true;
> +}
> +
> +static void *data_plane_thread(void *opaque)
> +{
> + VirtIOBlockDataPlane *s = opaque;
> + event_poll_run(&s->event_poll);
> + return NULL;
> +}
> +
> +static void start_data_plane_bh(void *opaque)
> +{
> + VirtIOBlockDataPlane *s = opaque;
> +
> + qemu_bh_delete(s->start_bh);
> + s->start_bh = NULL;
> + qemu_thread_create(&s->thread, data_plane_thread,
> + s, QEMU_THREAD_JOINABLE);
> +}
> +
> +VirtIOBlockDataPlane *virtio_blk_data_plane_create(VirtIODevice *vdev, int fd)
> +{
> + VirtIOBlockDataPlane *s;
> +
> + s = g_new0(VirtIOBlockDataPlane, 1);
> + s->vdev = vdev;
> + s->fd = fd;
> + return s;
> +}
> +
> +void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s)
> +{
> + if (!s) {
> + return;
> + }
> + virtio_blk_data_plane_stop(s);
> + g_free(s);
> +}
> +
> +/* Block until pending requests have completed
> + *
> + * The vring continues to be serviced so ensure no new requests will be added
> + * to avoid races.
> + */
> +void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s)
> +{
> + qemu_mutex_lock(&s->num_reqs_lock);
> + while (s->num_reqs > 0) {
> + qemu_cond_wait(&s->no_reqs_cond, &s->num_reqs_lock);
> + }
> + qemu_mutex_unlock(&s->num_reqs_lock);
> +}
> +
> +void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s)
> +{
> + VirtQueue *vq;
> + int i;
> +
> + if (s->started) {
> + return;
> + }
> +
> + vq = virtio_get_queue(s->vdev, 0);
> + if (!vring_setup(&s->vring, s->vdev, 0)) {
> + return;
> + }
> +
> + event_poll_init(&s->event_poll);
> +
> + /* Set up guest notifier (irq) */
> + if (s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque,
> + true) != 0) {
> + fprintf(stderr, "virtio-blk failed to set guest notifier, "
> + "ensure -enable-kvm is set\n");
> + exit(1);
> + }
> + s->guest_notifier = virtio_queue_get_guest_notifier(vq);
> +
> + /* Set up virtqueue notify */
> + if (s->vdev->binding->set_host_notifier(s->vdev->binding_opaque,
> + 0, true) != 0) {
> + fprintf(stderr, "virtio-blk failed to set host notifier\n");
> + exit(1);
> + }
> + event_poll_add(&s->event_poll, &s->notify_handler,
> + virtio_queue_get_host_notifier(vq),
> + handle_notify);
> +
> + /* Set up ioqueue */
> + ioq_init(&s->ioqueue, s->fd, REQ_MAX);
> + for (i = 0; i < ARRAY_SIZE(s->requests); i++) {
> + ioq_put_iocb(&s->ioqueue, &s->requests[i].iocb);
> + }
> + event_poll_add(&s->event_poll, &s->io_handler,
> + ioq_get_notifier(&s->ioqueue), handle_io);
> +
> + s->started = true;
> + trace_virtio_blk_data_plane_start(s);
> +
> + /* Kick right away to begin processing requests already in vring */
> + event_notifier_set(virtio_queue_get_host_notifier(vq));
> +
> + /* Spawn thread in BH so it inherits iothread cpusets */
> + s->start_bh = qemu_bh_new(start_data_plane_bh, s);
> + qemu_bh_schedule(s->start_bh);
> +}
> +
> +void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s)
> +{
> + if (!s->started) {
> + return;
> + }
> + s->started = false;
> + trace_virtio_blk_data_plane_stop(s);
> +
> + /* Stop thread or cancel pending thread creation BH */
> + if (s->start_bh) {
> + qemu_bh_delete(s->start_bh);
> + s->start_bh = NULL;
> + } else {
> + virtio_blk_data_plane_drain(s);
> + event_poll_stop(&s->event_poll);
> + qemu_thread_join(&s->thread);
> + }
> +
> + ioq_cleanup(&s->ioqueue);
> +
> + s->vdev->binding->set_host_notifier(s->vdev->binding_opaque, 0, false);
> +
> + event_poll_cleanup(&s->event_poll);
> +
> + /* Clean up guest notifier (irq) */
> + s->vdev->binding->set_guest_notifiers(s->vdev->binding_opaque, false);
> +
> + vring_teardown(&s->vring);
> +}
> diff --git a/hw/dataplane/virtio-blk.h b/hw/dataplane/virtio-blk.h
> new file mode 100644
> index 0000000..ddf1115
> --- /dev/null
> +++ b/hw/dataplane/virtio-blk.h
> @@ -0,0 +1,41 @@
> +/*
> + * Dedicated thread for virtio-blk I/O processing
> + *
> + * Copyright 2012 IBM, Corp.
> + * Copyright 2012 Red Hat, Inc. and/or its affiliates
> + *
> + * Authors:
> + * Stefan Hajnoczi <stefanha@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + *
> + */
> +
> +#ifndef HW_DATAPLANE_VIRTIO_BLK_H
> +#define HW_DATAPLANE_VIRTIO_BLK_H
> +
> +#include "hw/virtio.h"
> +
> +typedef struct VirtIOBlockDataPlane VirtIOBlockDataPlane;
> +
> +#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
> +VirtIOBlockDataPlane *virtio_blk_data_plane_create(VirtIODevice *vdev, int fd);
> +void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s);
> +void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s);
> +void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s);
> +void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s);
> +#else
> +static inline VirtIOBlockDataPlane *virtio_blk_data_plane_create(
> + VirtIODevice *vdev, int fd)
> +{
> + return NULL;
> +}
> +
> +static inline void virtio_blk_data_plane_destroy(VirtIOBlockDataPlane *s) {}
> +static inline void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) {}
> +static inline void virtio_blk_data_plane_stop(VirtIOBlockDataPlane *s) {}
> +static inline void virtio_blk_data_plane_drain(VirtIOBlockDataPlane *s) {}
> +#endif
> +
> +#endif /* HW_DATAPLANE_VIRTIO_BLK_H */
> diff --git a/trace-events b/trace-events
> index a9a791b..1edc2ae 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -98,6 +98,12 @@ virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
> virtio_blk_handle_write(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
> virtio_blk_handle_read(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
>
> +# hw/dataplane/virtio-blk.c
> +virtio_blk_data_plane_start(void *s) "dataplane %p"
> +virtio_blk_data_plane_stop(void *s) "dataplane %p"
> +virtio_blk_data_plane_process_request(void *s, unsigned int out_num, unsigned int in_num, unsigned int head) "dataplane %p out_num %u in_num %u head %u"
> +virtio_blk_data_plane_complete_request(void *s, unsigned int head, int ret) "dataplane %p head %u ret %d"
> +
> # hw/dataplane/vring.c
> vring_setup(uint64_t physical, void *desc, void *avail, void *used) "vring physical %#"PRIx64" desc %p avail %p used %p"
>
> --
> 1.8.0
^ permalink raw reply [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code
2012-11-20 13:04 ` Michael S. Tsirkin
@ 2012-11-20 13:54 ` Stefan Hajnoczi
0 siblings, 0 replies; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 13:54 UTC (permalink / raw)
To: Michael S. Tsirkin
Cc: Kevin Wolf, Anthony Liguori, rusty, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 03:04:53PM +0200, Michael S. Tsirkin wrote:
> On Tue, Nov 20, 2012 at 01:31:51PM +0100, Stefan Hajnoczi wrote:
> > +static void process_request(IOQueue *ioq, struct iovec iov[],
> > + unsigned int out_num, unsigned int in_num,
> > + unsigned int head)
> > +{
> > + /* Virtio block requests look like this: */
> > + struct virtio_blk_outhdr *outhdr; /* iov[0] */
> > + /* data[] ... */
> > + struct virtio_blk_inhdr *inhdr; /* iov[out_num + in_num - 1] */
> > +
> > + if (unlikely(out_num == 0 || in_num == 0 ||
> > + iov[0].iov_len != sizeof *outhdr ||
> > + iov[out_num + in_num - 1].iov_len != sizeof *inhdr)) {
> > + fprintf(stderr, "virtio-blk invalid request\n");
> > + exit(1);
> > + }
> > +
> > + outhdr = iov[0].iov_base;
> > + inhdr = iov[out_num + in_num - 1].iov_base;
> > +
>
> Rusty is trying to get rid of hard-coded layout assumptions,
> let's not add any more if we can help it.
Will try to abstract the iov arrays in the next version. Still not a
fan of doing this because it complicates the code for little gain.
Stefan
^ permalink raw reply [flat|nested] 21+ messages in thread
* [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature
2012-11-20 12:31 [Qemu-devel] [PATCH v2 0/8] virtio: virtio-blk data plane Stefan Hajnoczi
` (6 preceding siblings ...)
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 7/8] dataplane: add virtio-blk data plane code Stefan Hajnoczi
@ 2012-11-20 12:31 ` Stefan Hajnoczi
2012-11-20 12:37 ` Daniel P. Berrange
7 siblings, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 12:31 UTC (permalink / raw)
To: qemu-devel
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
The virtio-blk-data-plane feature is easy to integrate into
hw/virtio-blk.c. The data plane can be started and stopped similar to
vhost-net.
Users can take advantage of the virtio-blk-data-plane feature using the
new -device virtio-blk-pci,x-data-plane=on property.
The x-data-plane name was chosen because at this stage the feature is
experimental and likely to see changes in the future.
If the VM configuration does not support virtio-blk-data-plane an error
message is printed. Although we could fall back to regular virtio-blk,
I prefer the explicit approach since it prompts the user to fix their
configuration if they want the performance benefit of
virtio-blk-data-plane.
Limitations:
* Only format=raw is supported
* Live migration is not supported
* Block jobs, hot unplug, and other operations fail with -EBUSY
* I/O throttling limits are ignored
* Only Linux hosts are supported due to Linux AIO usage
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
hw/virtio-blk.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
hw/virtio-blk.h | 1 +
hw/virtio-pci.c | 3 +++
3 files changed, 62 insertions(+), 1 deletion(-)
diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index e25cc96..7f6004e 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -17,6 +17,8 @@
#include "hw/block-common.h"
#include "blockdev.h"
#include "virtio-blk.h"
+#include "hw/dataplane/virtio-blk.h"
+#include "migration.h"
#include "scsi-defs.h"
#ifdef __linux__
# include <scsi/sg.h>
@@ -33,6 +35,8 @@ typedef struct VirtIOBlock
VirtIOBlkConf *blk;
unsigned short sector_mask;
DeviceState *qdev;
+ VirtIOBlockDataPlane *dataplane;
+ Error *migration_blocker;
} VirtIOBlock;
static VirtIOBlock *to_virtio_blk(VirtIODevice *vdev)
@@ -407,6 +411,14 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, VirtQueue *vq)
.num_writes = 0,
};
+ /* Some guests kick before setting VIRTIO_CONFIG_S_DRIVER_OK so start
+ * dataplane here instead of waiting for .set_status().
+ */
+ if (s->dataplane) {
+ virtio_blk_data_plane_start(s->dataplane);
+ return;
+ }
+
while ((req = virtio_blk_get_request(s))) {
virtio_blk_handle_request(req, &mrb);
}
@@ -446,8 +458,13 @@ static void virtio_blk_dma_restart_cb(void *opaque, int running,
{
VirtIOBlock *s = opaque;
- if (!running)
+ if (!running) {
+ /* qemu_drain_all() doesn't know about data plane, quiesce here */
+ if (s->dataplane) {
+ virtio_blk_data_plane_drain(s->dataplane);
+ }
return;
+ }
if (!s->bh) {
s->bh = qemu_bh_new(virtio_blk_dma_restart_bh, s);
@@ -538,6 +555,10 @@ static void virtio_blk_set_status(VirtIODevice *vdev, uint8_t status)
VirtIOBlock *s = to_virtio_blk(vdev);
uint32_t features;
+ if (s->dataplane && !(status & VIRTIO_CONFIG_S_DRIVER)) {
+ virtio_blk_data_plane_stop(s->dataplane);
+ }
+
if (!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
return;
}
@@ -604,6 +625,7 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
{
VirtIOBlock *s;
static int virtio_blk_id;
+ int fd = -1;
if (!blk->conf.bs) {
error_report("drive property not set");
@@ -619,6 +641,21 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
return NULL;
}
+ if (blk->data_plane) {
+ if (blk->scsi) {
+ error_report("device is incompatible with x-data-plane, "
+ "use scsi=off");
+ return NULL;
+ }
+
+ fd = raw_get_aio_fd(blk->conf.bs);
+ if (fd < 0) {
+ error_report("drive is incompatible with x-data-plane, "
+ "use format=raw,cache=none,aio=native");
+ return NULL;
+ }
+ }
+
s = (VirtIOBlock *)virtio_common_init("virtio-blk", VIRTIO_ID_BLOCK,
sizeof(struct virtio_blk_config),
sizeof(VirtIOBlock));
@@ -636,6 +673,17 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
s->vq = virtio_add_queue(&s->vdev, 128, virtio_blk_handle_output);
+ if (fd >= 0) {
+ s->dataplane = virtio_blk_data_plane_create(&s->vdev, fd);
+
+ /* Prevent block operations that conflict with data plane thread */
+ bdrv_set_in_use(s->bs, 1);
+
+ error_setg(&s->migration_blocker,
+ "x-data-plane does not support migration");
+ migrate_add_blocker(s->migration_blocker);
+ }
+
qemu_add_vm_change_state_handler(virtio_blk_dma_restart_cb, s);
s->qdev = dev;
register_savevm(dev, "virtio-blk", virtio_blk_id++, 2,
@@ -652,6 +700,15 @@ VirtIODevice *virtio_blk_init(DeviceState *dev, VirtIOBlkConf *blk)
void virtio_blk_exit(VirtIODevice *vdev)
{
VirtIOBlock *s = to_virtio_blk(vdev);
+
+ if (s->dataplane) {
+ migrate_del_blocker(s->migration_blocker);
+ error_free(s->migration_blocker);
+ bdrv_set_in_use(s->bs, 0);
+ virtio_blk_data_plane_destroy(s->dataplane);
+ s->dataplane = NULL;
+ }
+
unregister_savevm(s->qdev, "virtio-blk", s);
blockdev_mark_auto_del(s->bs);
virtio_cleanup(vdev);
diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h
index f0740d0..53d7971 100644
--- a/hw/virtio-blk.h
+++ b/hw/virtio-blk.h
@@ -105,6 +105,7 @@ struct VirtIOBlkConf
char *serial;
uint32_t scsi;
uint32_t config_wce;
+ uint32_t data_plane;
};
#define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 71f4fb5..32cc910 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -897,6 +897,9 @@ static Property virtio_blk_properties[] = {
#endif
DEFINE_PROP_BIT("config-wce", VirtIOPCIProxy, blk.config_wce, 0, true),
DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
+#ifdef CONFIG_VIRTIO_BLK_DATA_PLANE
+ DEFINE_PROP_BIT("x-data-plane", VirtIOPCIProxy, blk.data_plane, 0, false),
+#endif
DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),
DEFINE_PROP_END_OF_LIST(),
--
1.8.0
^ permalink raw reply related [flat|nested] 21+ messages in thread* Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature
2012-11-20 12:31 ` [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature Stefan Hajnoczi
@ 2012-11-20 12:37 ` Daniel P. Berrange
2012-11-20 12:53 ` Kevin Wolf
2012-11-20 13:50 ` Stefan Hajnoczi
0 siblings, 2 replies; 21+ messages in thread
From: Daniel P. Berrange @ 2012-11-20 12:37 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 01:31:52PM +0100, Stefan Hajnoczi wrote:
> The virtio-blk-data-plane feature is easy to integrate into
> hw/virtio-blk.c. The data plane can be started and stopped similar to
> vhost-net.
>
> Users can take advantage of the virtio-blk-data-plane feature using the
> new -device virtio-blk-pci,x-data-plane=on property.
>
> The x-data-plane name was chosen because at this stage the feature is
> experimental and likely to see changes in the future.
Can you give some indication of how it is likely to change, since
this has a bearing on any libvirt use of this feature ?
Daniel
--
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|: http://libvirt.org -o- http://virt-manager.org :|
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^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature
2012-11-20 12:37 ` Daniel P. Berrange
@ 2012-11-20 12:53 ` Kevin Wolf
2012-11-20 13:50 ` Stefan Hajnoczi
1 sibling, 0 replies; 21+ messages in thread
From: Kevin Wolf @ 2012-11-20 12:53 UTC (permalink / raw)
To: Daniel P. Berrange
Cc: Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
Am 20.11.2012 13:37, schrieb Daniel P. Berrange:
> On Tue, Nov 20, 2012 at 01:31:52PM +0100, Stefan Hajnoczi wrote:
>> The virtio-blk-data-plane feature is easy to integrate into
>> hw/virtio-blk.c. The data plane can be started and stopped similar to
>> vhost-net.
>>
>> Users can take advantage of the virtio-blk-data-plane feature using the
>> new -device virtio-blk-pci,x-data-plane=on property.
>>
>> The x-data-plane name was chosen because at this stage the feature is
>> experimental and likely to see changes in the future.
>
> Can you give some indication of how it is likely to change, since
> this has a bearing on any libvirt use of this feature ?
I suppose the intended semantics is "libvirt, don't touch this!"
Maybe we could document the x-... prefix for experimental features that
may be changed in incompatible ways or removed in future versions, and
that no management tools should use.
Kevin
^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature
2012-11-20 12:37 ` Daniel P. Berrange
2012-11-20 12:53 ` Kevin Wolf
@ 2012-11-20 13:50 ` Stefan Hajnoczi
2012-11-20 14:34 ` Daniel P. Berrange
1 sibling, 1 reply; 21+ messages in thread
From: Stefan Hajnoczi @ 2012-11-20 13:50 UTC (permalink / raw)
To: Daniel P. Berrange
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 12:37:08PM +0000, Daniel P. Berrange wrote:
> On Tue, Nov 20, 2012 at 01:31:52PM +0100, Stefan Hajnoczi wrote:
> > The virtio-blk-data-plane feature is easy to integrate into
> > hw/virtio-blk.c. The data plane can be started and stopped similar to
> > vhost-net.
> >
> > Users can take advantage of the virtio-blk-data-plane feature using the
> > new -device virtio-blk-pci,x-data-plane=on property.
> >
> > The x-data-plane name was chosen because at this stage the feature is
> > experimental and likely to see changes in the future.
>
> Can you give some indication of how it is likely to change, since
> this has a bearing on any libvirt use of this feature ?
The following expectations:
1. This is an experimental feature. It can be enabled through libvirt
using <qemu:commandline>.
2. There is ongoing work to break down the global mutex in QEMU, which
will allow virtio-blk-data-plane functionality to become the
virtio-blk emulation default. At that point no command-line options
will be necessary (migration and image formats will be supported).
So I think there's no need for libvirt to do anything here.
Stefan
^ permalink raw reply [flat|nested] 21+ messages in thread
* Re: [Qemu-devel] [PATCH v2 8/8] virtio-blk: add x-data-plane=on|off performance feature
2012-11-20 13:50 ` Stefan Hajnoczi
@ 2012-11-20 14:34 ` Daniel P. Berrange
0 siblings, 0 replies; 21+ messages in thread
From: Daniel P. Berrange @ 2012-11-20 14:34 UTC (permalink / raw)
To: Stefan Hajnoczi
Cc: Kevin Wolf, Anthony Liguori, Michael S. Tsirkin, qemu-devel, khoa,
Stefan Hajnoczi, Paolo Bonzini, asias
On Tue, Nov 20, 2012 at 02:50:02PM +0100, Stefan Hajnoczi wrote:
> On Tue, Nov 20, 2012 at 12:37:08PM +0000, Daniel P. Berrange wrote:
> > On Tue, Nov 20, 2012 at 01:31:52PM +0100, Stefan Hajnoczi wrote:
> > > The virtio-blk-data-plane feature is easy to integrate into
> > > hw/virtio-blk.c. The data plane can be started and stopped similar to
> > > vhost-net.
> > >
> > > Users can take advantage of the virtio-blk-data-plane feature using the
> > > new -device virtio-blk-pci,x-data-plane=on property.
> > >
> > > The x-data-plane name was chosen because at this stage the feature is
> > > experimental and likely to see changes in the future.
> >
> > Can you give some indication of how it is likely to change, since
> > this has a bearing on any libvirt use of this feature ?
>
> The following expectations:
>
> 1. This is an experimental feature. It can be enabled through libvirt
> using <qemu:commandline>.
>
> 2. There is ongoing work to break down the global mutex in QEMU, which
> will allow virtio-blk-data-plane functionality to become the
> virtio-blk emulation default. At that point no command-line options
> will be necessary (migration and image formats will be supported).
>
> So I think there's no need for libvirt to do anything here.
Thanks for clarifying, Kevin / Stefan. Based on this info, we'll do nothing
with this in libvirt, in the expection that it'll become the default when
QEMU is ready for it.
Daniel
--
|: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :|
|: http://libvirt.org -o- http://virt-manager.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
^ permalink raw reply [flat|nested] 21+ messages in thread