From mboxrd@z Thu Jan  1 00:00:00 1970
From: Raghavendra K T <raghukt@linux.vnet.ibm.com>
Subject: Re: [PATCH RFC V2 3/5] kvm hypervisor : Add two hypercalls to support
 pv-ticketlock
Date: Mon, 24 Oct 2011 16:50:07 +0530
Message-ID: <4EA549E7.9090601@linux.vnet.ibm.com>
References: <20111023190307.16364.35381.sendpatchset@oc5400248562.ibm.com> <20111023190558.16364.2136.sendpatchset@oc5400248562.ibm.com> <4EA53A7D.300@redhat.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
	Greg Kroah-Hartman <gregkh@suse.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Gleb Natapov <gleb@redhat.com>,
	Virtualization <virtualization@lists.linux-foundation.org>,
	Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>,
	x86@kernel.org, KVM <kvm@vger.kernel.org>,
	Dave Jiang <dave.jiang@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
	Xen <xen-devel@lists.xensource.com>,
	Sedat Dilek <sedat.dilek@gmail.com>,
	Yinghai Lu <yinghai@kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	Ingo Molnar <mingo@redhat.com>, Rik van Riel <riel@redhat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Suzuki Poulose <suzuki@linux.vnet.ibm.com>,
	Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@redhat.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <4EA53A7D.300@redhat.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: kvm.vger.kernel.org

On 10/24/2011 03:44 PM, Avi Kivity wrote:
> On 10/23/2011 09:05 PM, Raghavendra K T wrote:
>> Add two hypercalls to KVM hypervisor to support pv-ticketlocks.
>> +
>> +end_wait:
>> +	finish_wait(&vcpu->wq,&wait);
>> +}
>
> This hypercall can be replaced by a HLT instruction, no?
>
> I'm pretty sure this misses a lot of stuff from kvm_vcpu_block().

Yes.. agree. HLT sounds better idea. 'll try this out.

>
>> +	if (vcpu) {
>> +		vcpu->kicked = 1;
>
> Need to use smp memory barriers here.

Agree.

>
>> +		wake_up_interruptible(&vcpu->wq);
>> +	}
>> +}
>> +
>>   int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
>>   {
>>   	unsigned long nr, a0, a1, a2, a3, ret;
>>
>