On Thu, Jul 23, 2015 at 03:36:43AM +0200, Marc-André Lureau wrote: > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
for some reason I didn't get 5/6. > --- > docs/specs/vhost-user.txt | 40 ++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 40 insertions(+) > > diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt > index 0062baa..c2d2e2a 100644 > --- a/docs/specs/vhost-user.txt > +++ b/docs/specs/vhost-user.txt > @@ -120,6 +120,7 @@ There are several messages that the master sends with > file descriptors passed > in the ancillary data: > > * VHOST_SET_MEM_TABLE > + * VHOST_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD) > * VHOST_SET_LOG_FD > * VHOST_SET_VRING_KICK > * VHOST_SET_VRING_CALL > @@ -135,6 +136,11 @@ As older slaves don't support negotiating protocol > features, > a feature bit was dedicated for this purpose: > #define VHOST_USER_F_PROTOCOL_FEATURES 30 > > +Protocol features > +----------------- > + > +#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 0 > + > Message types > ------------- > > @@ -301,3 +307,37 @@ Message types > Bits (0-7) of the payload contain the vring index. Bit 8 is the > invalid FD flag. This flag is set when there is no file descriptor > in the ancillary data. > + > +Migration > +--------- > + > +During live migration, the master may need to track the modifications > +the slave makes to the memory mapped regions. The client should mark > +the dirty pages in a log. Once it complies to this logging, it may > +declare VHOST_F_LOG_ALL has a vhost feature. > + > +All the modifications to memory pointed by vring "descriptor" should > +be marked. Modifications to "used" vring should be marked if > +VHOST_VRING_F_LOG is part of ring's features. It's device's features I think. > + > +Dirty pages are of size: > +#define VHOST_LOG_PAGE 0x1000 > + > +The log memory fd is provided in the ancillary data of > +VHOST_USER_SET_LOG_BASE message when the slave has > +VHOST_USER_PROTOCOL_F_LOG_SHMFD protocol feature. > + > +The size of the log may be computed by using all the known guest > +addresses. The log covers from address 0 to the maximum of guest > +regions. In pseudo-code, to mark page at "addr" as dirty: > + > +page = addr / VHOST_LOG_PAGE > +log[page / 8] |= 1 << page % 8 Pls note it must be done atomically. > + > +VHOST_USER_SET_LOG_FD is an optional message with an eventfd in > +ancillary data, it may be used to inform the master that the log has > +been modified. > + > +Once the source has finished migration, VHOST_USER_RESET_OWNER message > +will be sent by the source. No further update must be done before the > +destination takes over with new regions & rings. > -- > 2.4.3
