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.
> + * 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"?
> +
> + 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
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