Hi

On Wed, Jul 7, 2021 at 9:35 PM Steve Sistare <steven.sistare@oracle.com>
wrote:

> Add a function that returns true if any ram_list block represents
> volatile memory.
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> ---
>  include/exec/memory.h |  8 ++++++++
>  softmmu/memory.c      | 30 ++++++++++++++++++++++++++++++
>  2 files changed, 38 insertions(+)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index b116f7c..7ad63f8 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -2649,6 +2649,14 @@ bool ram_block_discard_is_disabled(void);
>   */
>  bool ram_block_discard_is_required(void);
>
> +/**
> + * qemu_ram_volatile: return true if any memory regions are writable and
> not
> + * backed by shared memory.
> + *
> + * @errp: returned error message identifying the bad region.
> + */
> +bool qemu_ram_volatile(Error **errp);
>

Usually, bool-value functions with an error return true on success. If it
deviates from the recommendation, it should at least be documented.

Also, we have a preference for using _is_ in the function name for such
tests.

+
>  #endif
>
>  #endif
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index f016151..e9536bc 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -2714,6 +2714,36 @@ void memory_global_dirty_log_stop(void)
>      memory_global_dirty_log_do_stop();
>  }
>
> +/*
> + * Return true if any memory regions are writable and not backed by shared
> + * memory.
> + */
>

Let's not duplicate API comments.

+bool qemu_ram_volatile(Error **errp)
> +{
> +    RAMBlock *block;
> +    MemoryRegion *mr;
> +    bool ret = false;
> +
> +    rcu_read_lock();
>

RCU_READ_LOCK_GUARD()


> +    QLIST_FOREACH_RCU(block, &ram_list.blocks, next) {
>

RAMBLOCK_FOREACH() should do.

Or rather use the qemu_ram_foreach_block() helper.


+        mr = block->mr;
> +        if (mr &&
> +            memory_region_is_ram(mr) &&
> +            !memory_region_is_ram_device(mr) &&
> +            !memory_region_is_rom(mr) &&
> +            (block->fd == -1 || !qemu_ram_is_shared(block))) {
> +
> +            error_setg(errp, "Memory region %s is volatile",
> +                       memory_region_name(mr));
> +            ret = true;
> +            break;
> +        }
> +    }
> +
> +    rcu_read_unlock();
> +    return ret;
> +}
> +
>  static void listener_add_address_space(MemoryListener *listener,
>                                         AddressSpace *as)
>  {
> --
> 1.8.3.1
>
>
>

-- 
Marc-André Lureau