Re: [Xen-devel] [PATCH for-4.5 RFC v2] x86/HVM: Unconditionally crash guests on repeated vmentry failures

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 25.11.14 at 17:54, <andrew.cooper3@xxxxxxxxxx> wrote:
> This is RFC as there is still a niggle.  I tested this via a partial revert of
> the XSA-110 fix but the result is quite chatty given a double VMCB dump and
> domain crash.  However, I am not sure we want to make any vmentry failure
> quite, as any vmentry failure constitues a Xen bug.

I think that double printing would be tolerable, but I've had yet
another idea: Couldn't we make the second exception a #DF,
thus having the guest killed via triple fault in the worst case at
the third recurring failure (via hvm_combine_hw_exceptions())?

Also your test results point out that we're delivering such an
exception with wrong context to the guest: Machine state should
match that before the results from the emulation got committed.
But doing so would be a pretty significant change for almost no
benefit.

Jan


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