From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Wanpeng Li" <wanpeng.li@hotmail.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Yunhong Jiang" <yunhong.jiang@intel.com>,
"Jan Kiszka" <jan.kiszka@siemens.com>,
"Haozhong Zhang" <haozhong.zhang@intel.com>
Subject: Re: [PATCH v3 2/2] KVM: nVMX: Fix preemption timer bit set in vmcs02 even if L1 doesn't enable it
Date: Thu, 7 Jul 2016 10:10:32 +0200 [thread overview]
Message-ID: <e3551fbc-0a48-9541-8344-81dd0d8ca801@redhat.com> (raw)
In-Reply-To: <1467863216-5521-2-git-send-email-wanpeng.li@hotmail.com>
On 07/07/2016 05:46, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
>
> We will go to vcpu_run() loop after L0 emulates VMRESUME which incurs
> kvm_sched_out and kvm_sched_in operations since cond_resched() will be
> called once need resched. Preemption timer will be reprogrammed if vCPU
> is scheduled to a different pCPU. Then the preemption timer bit of vmcs02
> will be set if L0 enable preemption timer to run L1 even if L1 doesn't
> enable preemption timer to run L2.
>
> This patch fix it by don't reprogram preemption timer of vmcs02 if L1's
> vCPU is scheduled on diffent pCPU when we are in the way to vmresume
> nested guest.
Again, this is wrong. There is no reason why L1's APIC timer cannot be
emulated through the vmcs12's preemption timer setting. The only issue
is getting the pin-based execution controls right.
Paolo
next prev parent reply other threads:[~2016-07-07 8:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-07 3:46 [PATCH v3 1/2] KVM: nVMX: Fix incorrect preemption timer vmexit in nested guest Wanpeng Li
2016-07-07 3:46 ` [PATCH v3 2/2] KVM: nVMX: Fix preemption timer bit set in vmcs02 even if L1 doesn't enable it Wanpeng Li
2016-07-07 8:10 ` Paolo Bonzini [this message]
2016-07-07 8:31 ` Wanpeng Li
2016-07-07 10:33 ` Paolo Bonzini
2016-07-07 10:54 ` Wanpeng Li
2016-07-07 6:48 ` [PATCH v3 1/2] KVM: nVMX: Fix incorrect preemption timer vmexit in nested guest Haozhong Zhang
2016-07-07 6:56 ` Wanpeng Li
2016-07-07 7:02 ` Haozhong Zhang
2016-07-07 7:07 ` Wanpeng Li
2016-07-07 7:25 ` Haozhong Zhang
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