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From: "Longpeng (Mike)" <longpeng2@huawei.com>
To: kevin.tian@intel.com, JBeulich@suse.com
Cc: xen-devel@lists.xenproject.org, xuquan8@huawei.com,
	Gonglei <arei.gonglei@huawei.com>,
	"Herongguang (Stephen)" <herongguang.he@huawei.com>,
	"Longpeng(Mike)" <longpeng2@huawei.com>
Subject: [Question] About the behavior of HLT in VMX guest mode
Date: Mon, 13 Mar 2017 13:12:40 +0800	[thread overview]
Message-ID: <58C62A48.6030203@huawei.com> (raw)

Hi guys,

I'm confusing about the behavior of HLT instruction in VMX guest mode.

I set "hlt exiting" bit to 0 in VMCS, and the vcpu didn't vmexit when execute
HLT as expected. However, I used powertop/cpupower on host to watch the pcpu's
c-states, it seems that the pcpu didn't enter C1/C1E state during this period.

I searched the Intel spec vol-3, and only found that guest MWAIT won't entering
a low-power sleep state under certain conditions(ch 25.3), but not mentioned HLT.

My questions are
1) Does executing HLT instruction in guest-mode won't enter C1/C1E state ?
2) If it won't, then whether it would release the hardware resources shared with
another hyper-thread ?

Any suggestion would be greatly appreciated, thanks!

-- 
Regards,
Longpeng(Mike)


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             reply	other threads:[~2017-03-13  5:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-13  5:12 Longpeng (Mike) [this message]
2017-03-13 11:38 ` [Question] About the behavior of HLT in VMX guest mode Jan Beulich
2017-03-14  1:11   ` Longpeng (Mike)
2017-03-13  6:12 Longpeng (Mike)
2017-03-13  7:12 Longpeng (Mike)
2017-03-15 17:32 ` Radim Krčmář
2017-03-16  2:08   ` Longpeng (Mike)
2017-03-16  2:48     ` Longpeng (Mike)
2017-03-16  8:51     ` Wanpeng Li
2017-03-16  9:19       ` Longpeng (Mike)
2017-03-16 14:23     ` Radim Krčmář
2017-03-17  5:22       ` Longpeng (Mike)
2017-03-20 15:18         ` Radim Krčmář
2017-03-21  1:47           ` Longpeng (Mike)
2017-03-21  6:21             ` Wanpeng Li
2017-03-21 16:45               ` Radim Krčmář
2017-07-04  4:24                 ` Wanpeng Li
2017-07-10 17:08                   ` Radim Krčmář
2017-07-11 10:41                     ` Wanpeng Li
2017-07-11 15:04                       ` Radim Krčmář

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