Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Wanpeng Li
On 9/16/15 1:20 PM, Jan Kiszka wrote: On 2015-09-16 04:36, Wanpeng Li wrote: 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 plen

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Jan Kiszka
On 2015-09-16 04:36, Wanpeng Li wrote: > 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? I

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Wanpeng Li
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 re

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Jan Kiszka
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 whi

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Wanpeng Li
On 9/15/15 12:08 AM, Bandan Das wrote: Wanpeng Li writes: VPID is used to tag address space and avoid a TLB flush. Currently L0 use the same VPID to run L1 and all its guests. KVM flushes VPID when switching between L1 and L2. This patch advertises VPID to the L1 hypervisor, then address spac

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-15 Thread Wanpeng Li
On 9/14/15 10:54 PM, Jan Kiszka wrote: On 2015-09-14 14:52, Wanpeng Li wrote: VPID is used to tag address space and avoid a TLB flush. Currently L0 use the same VPID to run L1 and all its guests. KVM flushes VPID when switching between L1 and L2. This patch advertises VPID to the L1 hypervisor,

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-14 Thread Bandan Das
Wanpeng Li writes: > VPID is used to tag address space and avoid a TLB flush. Currently L0 use > the same VPID to run L1 and all its guests. KVM flushes VPID when switching > between L1 and L2. > > This patch advertises VPID to the L1 hypervisor, then address space of L1 and > L2 can be separ

Re: [PATCH] KVM: nVMX: nested VPID emulation

2015-09-14 Thread Jan Kiszka
On 2015-09-14 14:52, Wanpeng Li wrote: > VPID is used to tag address space and avoid a TLB flush. Currently L0 use > the same VPID to run L1 and all its guests. KVM flushes VPID when switching > between L1 and L2. > > This patch advertises VPID to the L1 hypervisor, then address space of L1 and

[PATCH] KVM: nVMX: nested VPID emulation

2015-09-14 Thread Wanpeng Li
VPID is used to tag address space and avoid a TLB flush. Currently L0 use the same VPID to run L1 and all its guests. KVM flushes VPID when switching between L1 and L2. This patch advertises VPID to the L1 hypervisor, then address space of L1 and L2 can be separately treated and avoid TLB flus