Re: [Xen-devel] [PATCH v12 1/9] x86: add generic resource (e.g. MSR) access hypercall

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.07.14 at 11:40, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 04/07/14 09:34, Dongxiao Xu wrote:
>> Add a generic resource access hypercall for tool stack or other
>> components, e.g., accessing MSR, port I/O, etc.
>>
>> Signed-off-by: Dongxiao Xu <dongxiao.xu@xxxxxxxxx>
> 
> This still permits a user of the hypercalls to play with EFER or
> SYSENTER_EIP, which obviously is a very bad thing.
> 
> There needs to be a whitelist of permitted MSRs which can be accessed.

Hmm, I'm not sure. One particular purpose I see here is to allow the
tool stack (or Dom0) access to MSRs Xen may not know about (yet).
Furthermore, this being a platform op, only the hardware domain
should ever have access, and it certainly ought to know what it's
doing. So the sum of these two considerations is: If at all, we may
want a black list here.

Jan


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