linux-kernel - Re: [PATCH 2/4] KVM: VMX: avoid double list add with VT-d posted interrupts

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: <821f022f-ff94-876d-2426-8b6ab35af65f@redhat.com>
Date:   Fri, 9 Jun 2017 09:29:45 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Longpeng <longpeng2@...wei.com>,
        Huangweidong <weidong.huang@...wei.com>,
        Gonglei <arei.gonglei@...wei.com>,
        wangxin <wangxinxin.wang@...wei.com>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH 2/4] KVM: VMX: avoid double list add with VT-d posted
 interrupts



On 09/06/2017 04:50, Peter Xu wrote:
> Even, I'm thinking whether we can unconditionally setup PDST only in
> pi_load(), then post_block() only needs to handle the NV bit.

No, you can't do that without fiddling with the blocked_vcpu lists in
pi_load.

> (PS. since I'm at here... could I ask why in pi_pre_block we need to
>  udpate PDST as well? I guess that decides who will run the
>  wakeup_handler code to kick the vcpu thread, but would that really
>  matter?)

For this one it's a yes. :)  I think it's not needed anymore indeed
after these patches; see this comment:

                /*
                 * The wakeup_handler expects the VCPU to be on the
                 * blocked_vcpu_list that matches ndst.  Interrupts
                 * are disabled so no preemption should happen, but
                 * err on the side of safety.
                 */

So we could add a WARN.

Paolo