linux-kernel - Re: [PATCH v3] xen/evtchn: Introduce new IOCTL to bind static evtchn

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Date:   Wed, 19 Jul 2023 17:22:09 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@...nel.org>
To:     Oleksandr Tyshchenko <Oleksandr_Tyshchenko@...m.com>
cc:     Rahul Singh <rahul.singh@....com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Juergen Gross <jgross@...e.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Jane Malalane <jane.malalane@...rix.com>
Subject: Re: [PATCH v3] xen/evtchn: Introduce new IOCTL to bind static
 evtchn

On Tue, 18 Jul 2023, Oleksandr Tyshchenko wrote:
> On 18.07.23 14:31, Rahul Singh wrote:
> 
> 
> Hello Rahul
> 
> 
> > Xen 4.17 supports the creation of static evtchns. To allow user space
> > application to bind static evtchns introduce new ioctl
> > "IOCTL_EVTCHN_BIND_STATIC". Existing IOCTL doing more than binding
> > that’s why we need to introduce the new IOCTL to only bind the static
> > event channels.
> > 
> > Static evtchns to be available for use during the lifetime of the
> > guest. When the application exits, __unbind_from_irq() ends up being
> > called from release() file operations because of that static evtchns
> > are getting closed. To avoid closing the static event channel, add the
> > new bool variable "is_static" in "struct irq_info" to mark the event
> > channel static when creating the event channel to avoid closing the
> > static evtchn.
> > 
> > Also, take this opportunity to remove the open-coded version of the
> > evtchn close in drivers/xen/evtchn.c file and use xen_evtchn_close().
> > 
> > Signed-off-by: Rahul Singh <rahul.singh@....com>
> > ---
> > v3:
> >   * Remove the open-coded version of the evtchn close in drivers/xen/evtchn.c
> 
> Thanks!
> 
> Looks like there is one unmentioned change in change-log since v2:
> * Make sure that evtchn hasn't been added yet before binding it in 
> evtchn_ioctl():case IOCTL_EVTCHN_BIND_STATIC
> 
> Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>

Acked-by: Stefano Stabellini <sstabellini@...nel.org>