linux-kernel - Re: [PATCH v2 3/5] xen/events: only register debug interrupt for 2-level events

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]

Date:   Thu, 22 Oct 2020 15:17:52 +0200
From:   Jan Beulich <jbeulich@...e.com>
To:     Jürgen Groß <jgross@...e.com>
Cc:     xen-devel@...ts.xenproject.org, x86@...nel.org,
        linux-kernel@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 3/5] xen/events: only register debug interrupt for
 2-level events

On 22.10.2020 15:09, Jürgen Groß wrote:
> On 22.10.20 12:35, Jan Beulich wrote:
>> On 22.10.2020 11:49, Juergen Gross wrote:
>>> @@ -2080,10 +2080,12 @@ void __init xen_init_IRQ(void)
>>>   	int ret = -EINVAL;
>>>   	evtchn_port_t evtchn;
>>>   
>>> -	if (fifo_events)
>>> +	if (xen_fifo_events)
>>>   		ret = xen_evtchn_fifo_init();
>>> -	if (ret < 0)
>>> +	if (ret < 0) {
>>>   		xen_evtchn_2l_init();
>>> +		xen_fifo_events = false;
>>> +	}
>>
>> Another note: While it may not matter right here, maybe better
>> first set the variable and the call the function?
> 
> I don't think this is really important, TBH.
> 
> This code is executed before other cpus are up and we'd have major
> other problems in case the sequence would really matter here.

Fair enough; I was thinking in particular that it ought to be
legitimate for xen_evtchn_2l_init() to BUG_ON(xen_fifo_events).

Jan