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[Qemu-devel] [RFC v2 08/32] postcopy: Add vhost-user flag for postcopy a
From: |
Dr. David Alan Gilbert (git) |
Subject: |
[Qemu-devel] [RFC v2 08/32] postcopy: Add vhost-user flag for postcopy and check it |
Date: |
Thu, 24 Aug 2017 20:27:06 +0100 |
From: "Dr. David Alan Gilbert" <address@hidden>
Add a vhost feature flag for postcopy support, and
use the postcopy notifier to check it before allowing postcopy.
Signed-off-by: Dr. David Alan Gilbert <address@hidden>
---
contrib/libvhost-user/libvhost-user.h | 1 +
docs/interop/vhost-user.txt | 10 +++++++++
hw/virtio/vhost-user.c | 40 ++++++++++++++++++++++++++++++++++-
3 files changed, 50 insertions(+), 1 deletion(-)
diff --git a/contrib/libvhost-user/libvhost-user.h
b/contrib/libvhost-user/libvhost-user.h
index acd019876d..95d0d34a28 100644
--- a/contrib/libvhost-user/libvhost-user.h
+++ b/contrib/libvhost-user/libvhost-user.h
@@ -34,6 +34,7 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_MQ = 0,
VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
VHOST_USER_PROTOCOL_F_RARP = 2,
+ VHOST_USER_PROTOCOL_F_PAGEFAULT = 7,
VHOST_USER_PROTOCOL_F_MAX
};
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index 954771d0d8..a279560eb0 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -273,6 +273,15 @@ Once the source has finished migration, rings will be
stopped by
the source. No further update must be done before rings are
restarted.
+In postcopy migration the slave is started before all the memory has been
+received from the source host, and care must be taken to avoid accessing pages
+that have yet to be received. The slave opens a 'userfault'-fd and registers
+the memory with it; this fd is then passed back over to the master.
+The master services requests on the userfaultfd for pages that are accessed
+and when the page is available it performs WAKE ioctl's on the userfaultfd
+to wake the stalled slave. The client indicates support for this via the
+VHOST_USER_PROTOCOL_F_PAGEFAULT feature.
+
IOMMU support
-------------
@@ -327,6 +336,7 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_MTU 4
#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
#define VHOST_USER_PROTOCOL_F_CROSS_ENDIAN 6
+#define VHOST_USER_PROTOCOL_F_PAGEFAULT 7
Master message types
--------------------
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 093675ed98..c51bbd1296 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -17,6 +17,8 @@
#include "sysemu/kvm.h"
#include "qemu/error-report.h"
#include "qemu/sockets.h"
+#include "migration/migration.h"
+#include "migration/postcopy-ram.h"
#include <sys/ioctl.h>
#include <sys/socket.h>
@@ -34,7 +36,7 @@ enum VhostUserProtocolFeature {
VHOST_USER_PROTOCOL_F_NET_MTU = 4,
VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
-
+ VHOST_USER_PROTOCOL_F_PAGEFAULT = 7,
VHOST_USER_PROTOCOL_F_MAX
};
@@ -123,8 +125,10 @@ static VhostUserMsg m __attribute__ ((unused));
#define VHOST_USER_VERSION (0x1)
struct vhost_user {
+ struct vhost_dev *dev;
CharBackend *chr;
int slave_fd;
+ NotifierWithReturn postcopy_notifier;
};
static bool ioeventfd_enabled(void)
@@ -720,6 +724,33 @@ out:
return ret;
}
+static int vhost_user_postcopy_notifier(NotifierWithReturn *notifier,
+ void *opaque)
+{
+ struct PostcopyNotifyData *pnd = opaque;
+ struct vhost_user *u = container_of(notifier, struct vhost_user,
+ postcopy_notifier);
+ struct vhost_dev *dev = u->dev;
+
+ switch (pnd->reason) {
+ case POSTCOPY_NOTIFY_PROBE:
+ if (!virtio_has_feature(dev->protocol_features,
+ VHOST_USER_PROTOCOL_F_PAGEFAULT)) {
+ /* TODO: Get the device name into this error somehow */
+ error_setg(pnd->errp,
+ "vhost-user backend not capable of postcopy");
+ return -ENOENT;
+ }
+ break;
+
+ default:
+ /* We ignore notifications we don't know */
+ break;
+ }
+
+ return 0;
+}
+
static int vhost_user_init(struct vhost_dev *dev, void *opaque)
{
uint64_t features, protocol_features;
@@ -731,6 +762,7 @@ static int vhost_user_init(struct vhost_dev *dev, void
*opaque)
u = g_new0(struct vhost_user, 1);
u->chr = opaque;
u->slave_fd = -1;
+ u->dev = dev;
dev->opaque = u;
err = vhost_user_get_features(dev, &features);
@@ -787,6 +819,9 @@ static int vhost_user_init(struct vhost_dev *dev, void
*opaque)
return err;
}
+ u->postcopy_notifier.notify = vhost_user_postcopy_notifier;
+ postcopy_add_notifier(&u->postcopy_notifier);
+
return 0;
}
@@ -797,6 +832,9 @@ static int vhost_user_cleanup(struct vhost_dev *dev)
assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);
u = dev->opaque;
+ if (u->postcopy_notifier.notify) {
+ postcopy_remove_notifier(&u->postcopy_notifier);
+ }
if (u->slave_fd >= 0) {
qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);
close(u->slave_fd);
--
2.13.5
- Re: [Qemu-devel] [RFC v2 03/32] migrate: Update ram_block_discard_range for shared, (continued)
- [Qemu-devel] [RFC v2 04/32] qemu_ram_block_host_offset, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 05/32] migration/ram: ramblock_recv_bitmap_test_byte_offset, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 06/32] postcopy: use UFFDIO_ZEROPAGE only when available, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 07/32] postcopy: Add notifier chain, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 08/32] postcopy: Add vhost-user flag for postcopy and check it,
Dr. David Alan Gilbert (git) <=
- [Qemu-devel] [RFC v2 09/32] vhost-user: Add 'VHOST_USER_POSTCOPY_ADVISE' message, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 10/32] vhub: Support sending fds back to qemu, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 11/32] vhub: Open userfaultfd, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 12/32] postcopy: Allow registering of fd handler, Dr. David Alan Gilbert (git), 2017/08/24
- [Qemu-devel] [RFC v2 13/32] vhost+postcopy: Register shared ufd with postcopy, Dr. David Alan Gilbert (git), 2017/08/24