Re: [Qemu-devel] [PATCH v7 27/42] postcopy: ram_enable_notify to switch on userfault

[Juan Quintela]

"Dr. David Alan Gilbert (git)" <address@hidden> wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Mark the area of RAM as 'userfault'
> Start up a fault-thread to handle any userfaults we might receive
> from it (to be filled in later)
>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> Reviewed-by: David Gibson <address@hidden>
> ---
>  include/migration/migration.h    |  3 ++
>  include/migration/postcopy-ram.h |  6 ++++
>  migration/postcopy-ram.c         | 69 
> +++++++++++++++++++++++++++++++++++++++-
>  migration/savevm.c               |  9 ++++++
>  4 files changed, 86 insertions(+), 1 deletion(-)
>
> diff --git a/include/migration/migration.h b/include/migration/migration.h
> index 98e2568..e6585c5 100644
> --- a/include/migration/migration.h
> +++ b/include/migration/migration.h
> @@ -69,6 +69,9 @@ struct MigrationIncomingState {
>       */
>      QemuEvent      main_thread_load_event;
>  
> +    QemuThread     fault_thread;

Best name ever?  Well, it could be "wrong_thread" O:-)
> +static void *postcopy_ram_fault_thread(void *opaque)
> +{
> +    MigrationIncomingState *mis = (MigrationIncomingState *)opaque;

Uneeded cast.

> +
> +    fprintf(stderr, "postcopy_ram_fault_thread\n");
> +    /* TODO: In later patch */
> +    qemu_sem_post(&mis->fault_thread_sem);
> +    while (1) {
> +        /* TODO: In later patch */
> +    }
> +
> +    return NULL;
> +}
> +
> +int postcopy_ram_enable_notify(MigrationIncomingState *mis)
> +{
> +    /* Create the fault handler thread and wait for it to be ready */
> +    qemu_sem_init(&mis->fault_thread_sem, 0);
> +    qemu_thread_create(&mis->fault_thread, "postcopy/fault",
> +                       postcopy_ram_fault_thread, mis, QEMU_THREAD_JOINABLE);
> +    qemu_sem_wait(&mis->fault_thread_sem);
> +    qemu_sem_destroy(&mis->fault_thread_sem);
> +
> +    /* Mark so that we get notified of accesses to unwritten areas */
> +    if (qemu_ram_foreach_block(ram_block_enable_notify, mis)) {
> +        return -1;
> +    }
> +
> +    return 0;
> +}
> +
>  #else
>  /* No target OS support, stubs just fail */
> -

This belongs in a different patch O:-)

If you have to resend, just change them.

Reviewed-by: Juan Quintela <address@hidden>