On 9/16/15 1:32 AM, Jan Kiszka wrote:
On 2015-09-15 12:14, Wanpeng Li wrote:
On 9/14/15 10:54 PM, Jan Kiszka wrote:
Last but not least: the guest can now easily exhaust the host's pool of
vpid by simply spawning plenty of VCPUs for L2, no? Is this acceptable
or should there be some limit?
I reuse the value of vpid02 while vpid12 changed w/ one invvpid in v2,
and the scenario which you pointed out can be avoid.
I cannot yet follow why there is no chance for L1 to consume all vpids
that the host manages in that single, global bitmap by simply spawning a
lot of nested VCPUs for some L2. What is enforcing L1 to call nested
vmclear - apparently the only way, besides destructing nested VCPUs, to
release such vpids again?
In v2, there is no direct mapping between vpid02 and vpid12, the vpid02
is per-vCPU for L0 and reused while the value of vpid12 is changed w/
one invvpid during nested vmentry. The vpid12 is allocated by L1 for L2,
so it will not influence global bitmap(for vpid01 and vpid02 allocation)
even if spawn a lot of nested vCPUs.
Regards,
Wanpeng Li
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