Re: [PATCH v4 2/5] x86/iommu: make code addressing CVE-2011-1898 no VT-d specific

[Xenia Ragiadakou <burzalodowa@xxxxxxxxx>]

On 2/1/23 07:07, Tian, Kevin wrote:
> > From: Xenia Ragiadakou <burzalodowa@xxxxxxxxx>
> > Sent: Tuesday, January 24, 2023 8:42 PM
> >
> > The variable untrusted_msi indicates whether the system is vulnerable to
> > CVE-2011-1898 due to the absence of interrupt remapping support.
> > Although AMD iommus with interrupt remapping disabled are also affected,
> > this case is not handled yet. Given that the issue is not VT-d specific,
> > and to accommodate future use of the flag for covering also the AMD iommu
> > case, move the definition of the flag out of the VT-d specific code to the
> > common x86 iommu code.
> >
> > Also, since the current implementation assumes that only PV guests are
> > prone
> > to this attack, take the opportunity to define untrusted_msi only when PV is
> > enabled.
> I'm fine with this change given no functional change.
>
> But I'm curious about the statement here that the current code only
> applies to PV guest. I didn't see such statement in original mail [1]
> and in concept a HVM guest with passthrough device can also do such
> attack w/o interrupt remapping.
>
> Any more context?
I agree. I phrased it that way because currently the mitigation 
addresses only maliciously injected PV traps.
> [1] 
> http://old-list-archives.xenproject.org/archives/html/xen-devel/2011-05/msg00687.html
--
Xenia