linux-kernel - Re: [PATCH] KVM: halt-polling: poll if emulated lapic timer will fire soon

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <573DA6A8.1000401@de.ibm.com>
Date:	Thu, 19 May 2016 13:42:32 +0200
From:	Christian Borntraeger <borntraeger@...ibm.com>
To:	Wanpeng Li <kernellwp@...il.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	kvm <kvm@...r.kernel.org>, Wanpeng Li <wanpeng.li@...mail.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	Radim Krčmář <rkrcmar@...hat.com>,
	David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH] KVM: halt-polling: poll if emulated lapic timer will fire
 soon

On 05/19/2016 01:35 PM, Wanpeng Li wrote:
> 2016-05-19 19:23 GMT+08:00 Christian Borntraeger <borntraeger@...ibm.com>:
>> On 05/19/2016 11:26 AM, Wanpeng Li wrote:
>>
>> I think in general a good idea to poll if a timer will expire soon.
>>
>> Some patch comments:
>>
>> Same for all non-x86 archs:
>>> +static inline unsigned int kvm_arch_timer_remaining(struct kvm_vcpu *vcpu) {}
>>
>> A function returning int, without a return statement?
>> That gives at least a compiler warning.
> 
> How about return 0 for all non-x86 archs?

We will provide an s390 implementation soon, but until then a proper
default would be good.

[....]
>>> +     if (vcpu->halt_poll_ns || (remaining < halt_poll_ns_base)) {

but then remaining is 0 and the 2nd condition will always be true, no?