Re: [Xen-devel] [PATCH 1/3] x86: don't allow Dom0 access to the MSI address range

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.08.13 at 16:48, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Wed, Aug 21, 2013 at 03:44:09PM +0100, Jan Beulich wrote:
>> >>> On 21.08.13 at 16:29, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> 
>> >>> wrote:
>> > On Wed, Aug 21, 2013 at 07:36:58AM +0100, Jan Beulich wrote:
>> >> In particular, MMIO assignments should not be done using this area.
>> > 
>> > And just to make sure there are no regressions - have you tested
>> > this with an upstream dom0 kernel to make sure it does not blow things up?
>> 
>> No, I didn't. I'm only testing with our own kernels. But I can't see
>> how this could cause any regression - Dom0 is not supposed to
>> map that page (from CPU perspective it's the LAPIC) one, and if
>> it ever assigned the range as MMIO to a device, things would have
>> blown up.
> 
> I see. What an odd name for an LAPIC region - MMIO.

The thing is that this address range has two meanings - to the
CPU it's the LAPIC range, to PCI devices it's the MSI address
one (which _is_ a special kind of MMIO).

Jan


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