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Date: Wed, 16 Sep 2015 10:36:04 +0800 From: Wanpeng Li <wanpeng.li@...mail.com> To: Jan Kiszka <jan.kiszka@...mens.com>, Paolo Bonzini <pbonzini@...hat.com> CC: kvm@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH] KVM: nVMX: nested VPID emulation 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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