Hi Paolo,
On 11/11/14, 1:28 AM, Paolo Bonzini wrote:
On 10/11/2014 15:23, Avi Kivity wrote:
It's not surprising [1]. Since the meaning of some PTE bits change [2],
the TLB has to be flushed. In VMX we have VPIDs, so we only need to flush
if EFER changed between two invocations of the same VPID, which isn't the
case.
If there need a TLB flush if guest is UP?
Regards,
Wanpeng Li
[1] after the fact
[2] although those bits were reserved with NXE=0, so they shouldn't have
any TLB footprint
You're right that this is not that surprising after the fact, and that
both Sandy Bridge and Ivy Bridge have VPIDs (even the non-Xeon ones).
This is also why I'm curious about the Nehalem.
However note that even toggling the SCE bit is flushing the TLB. The
NXE bit is not being toggled here! That's the more surprising part.
Paolo
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