Re: [Xen-devel] [PATCH v2 5/5] x86/pv: Expose RDTSCP to PV guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.11.18 at 15:37, <andrew.cooper3@xxxxxxxxxx> wrote:
> The final remnanat of PVRDTSCP is that we would emulate RDTSCP even on
> hardware which lacked the instruction.  RDTSCP is available on almost all
> 64-bit x86 hardware.
> 
> Remove this emulation, drop the TSC_MODE_PVRDTSCP constant, and allow RDTSCP
> in a PV guest's CPUID policy.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

In the interest of not holding up things
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
but I would have appreciated if you had responded on the v1
thread, as I continue to fail to see the meaningfully larger
attack surface with the emulation left in place.

Jan



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