linux-kernel - Re: [PATCH v4 02/17] x86/acrn: Introduce acrn_{setup, remove}_intr

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: <20200930030244.GI1057@shuo-intel.sh.intel.com>
Date:   Wed, 30 Sep 2020 11:02:44 +0800
From:   Shuo A Liu <shuo.a.liu@...el.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
        x86@...nel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Yu Wang <yu1.wang@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Yakui Zhao <yakui.zhao@...el.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Fengwei Yin <fengwei.yin@...el.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>
Subject: Re: [PATCH v4 02/17] x86/acrn: Introduce acrn_{setup,
 remove}_intr_handler()

Hi Boris,

On Tue 29.Sep'20 at 22:26:54 +0200, Borislav Petkov wrote:
>On Tue, Sep 29, 2020 at 10:07:17PM +0200, Thomas Gleixner wrote:
>> That does not prevent that either and notifiers suck.
>
>Bah, atomic notifiers run functions which cannot block, not what is
>needed here, right.
>
>> The pointer is fine and if something removes the handler before all of
>> the muck is shutdown then the author can keep the pieces and mop up
>> the remains.
>
>Uhu, so what makes sure that the module is not removed while an IRQ is
>happening?

The precondition of the removing of the module is that there is no
User VM living (every opening of the dev file will hold a ref count of
the module). The interrupt only can occur with active User VMs. So if
a notification interrupt is happending, the module cannot be removed as
there is still User VM living.

Thanks
shuo