linux-kernel - Re: [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4FFE8BA1.8000507@linux.vnet.ibm.com>
Date:	Thu, 12 Jul 2012 14:02:33 +0530
From:	Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Christian Borntraeger <borntraeger@...ibm.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Ingo Molnar <mingo@...hat.com>, Rik van Riel <riel@...hat.com>,
	S390 <linux-s390@...r.kernel.org>,
	Carsten Otte <cotte@...ibm.com>, KVM <kvm@...r.kernel.org>,
	chegu vinod <chegu_vinod@...com>,
	"Andrew M. Theurer" <habanero@...ux.vnet.ibm.com>,
	LKML <linux-kernel@...r.kernel.org>, X86 <x86@...nel.org>,
	Gleb Natapov <gleb@...hat.com>, linux390@...ibm.com,
	Srivatsa Vaddagiri <srivatsa.vaddagiri@...il.com>,
	Joerg Roedel <joerg.roedel@....com>,
	Christian Ehrhardt <ehrhardt@...ux.vnet.ibm.com>,
	Alexander Graf <agraf@...e.de>,
	Paul Mackerras <paulus@...ba.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: Re: [PATCH RFC 0/2] kvm: Improving directed yield in PLE handler

On 07/12/2012 01:41 PM, Avi Kivity wrote:
> On 07/12/2012 08:11 AM, Raghavendra K T wrote:
>>> Ah, I thouht you objected to the CONFIG var.  Maybe call it
>>> cpu_relax_intercepted since that's the linuxy name for the instruction.
>>>
>>
>> Ok, just to be on same page. 'll have :
>> 1. cpu_relax_intercepted instead of  pause_loop_exited.
>>
>> 2. CONFIG_KVM_HAVE_CPU_RELAX_INTERCEPT which is unconditionally
>> selected for x86 and s390
>>
>> 3. make request mechanism to clear cpu_relax_intercepted.
>>
>> ('ll do same thing for s390 also but have not seen s390 code using
>> request mechanism, so not sure if it ok.. otherwise we have to clear
>> unconditionally for s390 before guest enter and for x86 we have to move
>> make_request back to vmx/svm).
>> will post V3 with these changes.
>
> You can leave the s390 changes to the s390 people; just make sure the
> generic code is ready.
>
Yep,
Checked the following logic with make_request and it works fine,

vcpu_spin()
{
  ple_exited = true;
.
.
make_request(KVM_REQ_CLEAR_PLE, vcpu);
}

vcpu_enter_guest()
{
  if(check_request(KVM_REQ_CLEAR_PLE))
     ple_exited = false;
.
.
}

But there is following approach that is working perfectly fine.
vcpu_spin()
{
  ple_exited = true;
.
.

  ple_exited = false;
}

I hope to go with second approach. let me know if you find any loop
hole.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/