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

>>> 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.

> Or at least if it does blow up - are there any WARN or BUG to help
> in coming up with a patch?

The E820 machine memory map that Dom0 gets to see would
have that range marked as reserved (or unusable), and the
MMIO rangeset printed in 'q' debug key output would also show
the page as not accessible.


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