Re: [Xen-devel] [PATCH V2] x86/altp2m: Fixed crash with INVALID_ALTP2M EPTP index

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.06.18 at 14:49, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
> So assuming that the HVMOPs are properly handled atomically with respect
> to their corresponding VCPU (which I now believe to be the case), the
> only possible issue that remains (that I can think of) is the case where
> EPTP_INDEX has been saved in a previous run of a test application, but
> is not correct for the current state of the guest.
> 
> Then HVMOP_altp2m_vcpu_enable_notify is handled,
> SECONDARY_EXEC_ENABLE_VIRT_EXCEPTIONS is set, and the VM exit handler is
> called, which would result in working with the wrong index. This, I
> believe, can be fixed by either calling altp2m_vcpu_update_p2m() all the
> time immediately after all altp2m_vcpu_update_vmfunc_ve() calls, or
> making it a part of altp2m_vcpu_update_vmfunc_ve() (hence my previous
> proposal).
> 
> Does that sound reasonable?

I think so, yes, if the pausing works as expected.

Jan



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