Re: [Qemu-devel] [RFC/PATCH] migration: SMRAM dirty bitmap not fetched from kvm-kmod and not send to destination

[Paolo Bonzini]

On 23/09/2016 10:51, Herongguang (Stephen) wrote:
> 
> 
> On 2016/9/23 15:17, Paolo Bonzini wrote:
>>
>>
>> On 22/09/2016 15:16, Herongguang (Stephen) wrote:
>>> I have some concern:
>>> 1. For example, vhost does not know about as_id, I wonder if guests in
>>> SMM can operate disk or ether card, as in
>>> that case vhost would not logging dirty pages correctly, without knowing
>>> as_id.
>>
>> In the end memory is logged by ram_addr_t, not by address space.  So if
>> vhost_sync_dirty_bitmap is called on the right region everything works.
>>
>> Guests in SMM can operate on storage devices, but storage devices cannot
>> write to 0xA0000-0xBFFFF so that's safe.
> You are right, as vhost does not have a smram address space listener. So
> is this a qemu's flaw that virtual devices can not write to SMRAM?

No, it's how it works in real hardware.  However, it is a (minor) bug
that vhost doesn't have the equivalent of kvm_set_phys_mem's call to
kvm_physical_sync_dirty_bitmap.

> Fine, your patch is simpler than I thought and functions right.

Great!

> Reviewed-by: He Rongguang <address@hidden>

Also Tested-by?

Thanks,

Paolo
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