Re: [Xen-devel] [PATCH 7/7] x86/mm: Prevent 32bit PV guests using out-of-range linear addresses

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 12.09.17 at 14:14, <andrew.cooper3@xxxxxxxxxx> wrote:
> The grant ABI uses 64 bit values, and allows a PV guest to specify linear
> addresses.  There is nothing interesting a 32bit PV guest can reference which
> will pass an __addr_ok() check, but it should still get an error for trying.

While I'm all for tightening checks, I'm not sure we reasonably can:
Existing guests may (perhaps inadvertently) rely on this behavior,
and hence may break with the change. I think a prereq to this is to
have a command line option (or even a per-guest one) to control
strict vs relaxed argument checking behavior, and tie the extra
checks to that option being true.

Jan


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