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From: Jan Kiszka <jan.kiszka@web.de>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Arthur Chunqi Li <yzt356@gmail.com>,
	kvm@vger.kernel.org, gleb@redhat.com, yang.z.zhang@intel.com
Subject: Re: [PATCH v4] KVM: nVMX: Fully support of nested VMX preemption timer
Date: Sat, 14 Sep 2013 09:44:15 +0200	[thread overview]
Message-ID: <523413CF.5080203@web.de> (raw)
In-Reply-To: <5233481F.8060606@redhat.com>

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On 2013-09-13 19:15, Paolo Bonzini wrote:
> Il 06/09/2013 04:04, Arthur Chunqi Li ha scritto:
>> +	preempt_val_l1 = delta_tsc_l1 >> preempt_scale;
>> +	if (preempt_val_l2 <= preempt_val_l1)
>> +		preempt_val_l2 = 0;
>> +	else
>> +		preempt_val_l2 -= preempt_val_l1;
>> +	vmcs_write32(VMX_PREEMPTION_TIMER_VALUE, preempt_val_l2);
> 
> Did you test that a value of 0 triggers an immediate exit, rather than
> counting down by 2^32?  Perhaps it's safer to limit the value to 1
> instead of 0.

To my experience, 0 triggers immediate exists when the preemption timer
is enabled.

Jan



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  reply	other threads:[~2013-09-14  7:44 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-06  2:04 [PATCH v4] KVM: nVMX: Fully support of nested VMX preemption timer Arthur Chunqi Li
2013-09-13 17:15 ` Paolo Bonzini
2013-09-14  7:44   ` Jan Kiszka [this message]
2013-09-15  7:59     ` Arthur Chunqi Li
2013-09-16  5:42   ` Arthur Chunqi Li
2013-09-16  7:18     ` Jan Kiszka
2013-09-16  7:44   ` Gleb Natapov
2013-09-16  8:58     ` Paolo Bonzini
2013-09-16  9:09       ` Gleb Natapov
2013-09-16  9:49         ` Paolo Bonzini
2013-09-16 10:44           ` Gleb Natapov
2013-09-16 10:50             ` Paolo Bonzini
2013-09-15 12:31 ` Gleb Natapov
2013-09-16  5:49   ` Arthur Chunqi Li
2013-09-16  6:20     ` Gleb Natapov

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