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Re: [Xen-devel] Xen Introspection, KPTI, and CR3 bit 63 leads to guest VMENTRY failures during introspection

On 01/26/2018 12:17 AM, Bitweasil . wrote:
> Razvan -
> Yes, that patch resolves the issues.  Performance is abysmal (as
> expected with a CR3 switch on every syscall), but things behave properly.>
> Jan -
> It turns out that unrelated code in my livepatch was causing the
> crashing when I filtered the high bit - I was not properly gating some
> other CR3 processing code in the livepatch, and that was causing the
> invalid opcode errors, not the filtered CR3 value.  You are correct that
> masking the bit should not cause any correctness issues, only
> performance issues.
> Will one of you take up submitting this patch into the proper places? 
> I'm afraid I'm not very familiar with the Xen patch submission process.

Yes, I'll send a proper patch.

Thanks for pointing the issue out,

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