From: Paolo Bonzini <pbonzini@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>, kvm <kvm@vger.kernel.org>,
Radim Krcmar <rkrcmar@redhat.com>,
Yunhong Jiang <yunhong.jiang@intel.com>,
Wanpeng Li <wanpeng.li@hotmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Jan Kiszka <jan.kiszka@siemens.com>
Subject: Re: [PATCH] KVM: VMX: switch to hrtimer for TSC deadline timer when L2 guest is running
Date: Wed, 6 Jul 2016 09:46:42 +0200 [thread overview]
Message-ID: <6d2cd9ce-da0e-8b61-e3a9-78be3b32a6e4@redhat.com> (raw)
In-Reply-To: <20160706060558.sklnb3qso6tnmbrs@hz-desktop>
On 06/07/2016 08:05, Haozhong Zhang wrote:
>> >
>> > Nested preemption timer is emulated by hrtimer, so it doesn't
>> > influence vmcs02, why this is needed?
> Nested (L2) preemption timer is not affected for sure, and this patch
> is to fix another problem caused by using L1 preemption timer for L1
> TSC deadline timer. When we use L1 VMX preemption timer for L1 TSC
> deadline timer, we intend to use the pin-based exec config and the VMX
> preemption timer value in vmcs01. However, when L2 guest is running,
> vmcs02 is loaded as the current VMCS so that a different VMX
> preemption timer config is used (i.e. VMX preemption timer is disabled
> in prepare_vmcs02()). If we still use preemption timer for L1 TSC
> deadline timer at this moment, then L1 TSC deadline timer will not be
> able to be triggered when L2 guest is running.
The right fix then is to set the pin-based controls in prepare_vmcs02,
based on vcpu->arch.hv_deadline_tsc.
Paolo
next prev parent reply other threads:[~2016-07-06 7:46 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-06 5:10 [PATCH] KVM: VMX: switch to hrtimer for TSC deadline timer when L2 guest is running Haozhong Zhang
2016-07-06 5:37 ` Wanpeng Li
2016-07-06 6:04 ` Paolo Bonzini
2016-07-06 6:05 ` Haozhong Zhang
2016-07-06 7:46 ` Paolo Bonzini [this message]
2016-07-06 8:01 ` Haozhong Zhang
2016-07-06 8:09 ` Haozhong Zhang
2016-07-06 8:14 ` Paolo Bonzini
2016-07-06 8:21 ` Haozhong Zhang
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