Re: [Xen-devel] [PATCH] x86/MSI: add mechanism to protect MSI-X table from PV guest accesses

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.02.13 at 06:17, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx> wrote:
> I think this fix also covers HVM side, right ?

The HVM case was already taken care of without this change.

>   For PV side,  I recalled 
> there was already a fix in Xend to protect PV guest from accessing the 
> related MMIO range.

There once was such a change, but iirc it got reverted quickly, and
no-one ever cared to restore it in a way that wouldn't break things.

Also, that wouldn't help xl in any way.

> Also for HVM guest, last year you proposed and submitted 
> a patch to Xen-Qemu for blocking guest's accesses to the related MMIO range.  
>  

Not quite - that change was a pre-req to make it possible to also
deny Dom0 access to that range, because qemu was incorrectly
mapping the range in question.

>  Looks like the previous fixes are not needed any more if this fix got 
> check-in, right ?  

They all will still be necessary. This change (or one of the described
alternatives) is only to close the remaining hole for PV guests.

Jan


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