Re: [PATCH V5 01/25] qemu_ram_volatile

[Steven Sistare <steven.sistare@oracle.com>]

Will do for all comments - steve

On 7/8/2021 8:01 AM, Marc-André Lureau wrote:
> Hi
> 
> On Wed, Jul 7, 2021 at 9:35 PM Steve Sistare <steven.sistare@oracle.com <mailto: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 <mailto: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