* David Gibson (da...@gibson.dropbear.id.au) wrote:
> On Fri, Oct 03, 2014 at 06:47:38PM +0100, Dr. David Alan Gilbert (git) wrote:
> > From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
> >
> > Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> > ---
> > include/migration/migration.h | 2 ++
> > include/migration/postcopy-ram.h | 6 +++++
> > postcopy-ram.c | 49
> > +++++++++++++++++++++++++++++++++++++++-
> > savevm.c | 9 ++++++++
> > 4 files changed, 65 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/migration/migration.h b/include/migration/migration.h
> > index be63c89..b01cc17 100644
> > --- a/include/migration/migration.h
> > +++ b/include/migration/migration.h
> > @@ -87,6 +87,8 @@ struct MigrationIncomingState {
> > POSTCOPY_RAM_INCOMING_END
> > } postcopy_ram_state;
> >
> > + /* For the kernel to send us notifications */
> > + int userfault_fd;
> > QEMUFile *return_path;
> > QemuMutex rp_mutex; /* We send replies from multiple threads */
> > PostcopyPMI postcopy_pmi;
> > diff --git a/include/migration/postcopy-ram.h
> > b/include/migration/postcopy-ram.h
> > index 8f237a2..413b670 100644
> > --- a/include/migration/postcopy-ram.h
> > +++ b/include/migration/postcopy-ram.h
> > @@ -19,6 +19,12 @@
> > int postcopy_ram_hosttest(void);
> >
> > /*
> > + * Make all of RAM sensitive to accesses to areas that haven't yet been
> > written
> > + * and wire up anything necessary to deal with it.
> > + */
> > +int postcopy_ram_enable_notify(MigrationIncomingState *mis);
> > +
> > +/*
> > * Initialise postcopy-ram, setting the RAM to a state where we can go into
> > * postcopy later; must be called prior to any precopy.
> > * called from arch_init's similarly named ram_postcopy_incoming_init
> > diff --git a/postcopy-ram.c b/postcopy-ram.c
> > index 8eccf26..925ac77 100644
> > --- a/postcopy-ram.c
> > +++ b/postcopy-ram.c
> > @@ -485,9 +485,51 @@ int
> > postcopy_ram_incoming_cleanup(MigrationIncomingState *mis)
> > return 0;
> > }
> >
> > +/*
> > + * Mark the given area of RAM as requiring notification to unwritten areas
> > + * Used as a callback on qemu_ram_foreach_block.
> > + * host_addr: Base of area to mark
> > + * offset: Offset in the whole ram arena
> > + * length: Length of the section
> > + * opaque: Unused
>
> ^^^^^^
> This appears to be wrong - opaque is used to find the MIS.
Fixed.
>
> > + * Returns 0 on success
> > + */
> > +static int postcopy_ram_sensitise_area(const char *block_name, void
> > *host_addr,
> > + ram_addr_t offset, ram_addr_t
> > length,
> > + void *opaque)
> > +{
> > + MigrationIncomingState *mis = opaque;
> > + uint64_t tokern[2];
>
> "tokern"?
Now "to_kernel"
Dave
>
> > +
> > + if (madvise(host_addr, length, MADV_USERFAULT)) {
> > + perror("postcopy_ram_sensitise_area madvise");
> > + return -1;
> > + }
> > +
> > + /* Now tell our userfault_fd that it's responsible for this area */
> > + tokern[0] = (uint64_t)(uintptr_t)host_addr | 1; /* 1 means register
> > area */
> > + tokern[1] = (uint64_t)(uintptr_t)host_addr + length;
> > + if (write(mis->userfault_fd, tokern, 16) != 16) {
> > + perror("postcopy_ram_sensitise_area write");
> > + madvise(host_addr, length, MADV_NOUSERFAULT);
> > + return -1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +int postcopy_ram_enable_notify(MigrationIncomingState *mis)
> > +{
> > + /* Mark so that we get notified of accesses to unwritten areas */
> > + if (qemu_ram_foreach_block(postcopy_ram_sensitise_area, mis)) {
> > + return -1;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > #else
> > /* No target OS support, stubs just fail */
> > -
> > int postcopy_ram_hosttest(void)
> > {
> > error_report("postcopy_ram_hosttest: No OS support");
> > @@ -528,6 +570,11 @@ int postcopy_ram_discard_range(MigrationIncomingState
> > *mis, uint8_t *start,
> > {
> > assert(0);
> > }
> > +
> > +int postcopy_ram_enable_notify(MigrationIncomingState *mis)
> > +{
> > + assert(0);
> > +}
> > #endif
> >
> > /*
> > ------------------------------------------------------------------------- */
> > diff --git a/savevm.c b/savevm.c
> > index 54bdb26..859c96f 100644
> > --- a/savevm.c
> > +++ b/savevm.c
> > @@ -1304,6 +1304,15 @@ static int
> > loadvm_postcopy_ram_handle_listen(MigrationIncomingState *mis)
> >
> > mis->postcopy_ram_state = POSTCOPY_RAM_INCOMING_LISTENING;
> >
> > + /*
> > + * Sensitise RAM - can now generate requests for blocks that don't
> > exist
> > + * However, at this point the CPU shouldn't be running, and the IO
> > + * shouldn't be doing anything yet so don't actually expect requests
> > + */
> > + if (postcopy_ram_enable_notify(mis)) {
> > + return -1;
> > + }
> > +
> > /* TODO start up the postcopy listening thread */
> > return 0;
> > }
>
> --
> David Gibson | I'll have my music baroque, and my code
> david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_
> _other_
> | _way_ _around_!
> http://www.ozlabs.org/~dgibson
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
