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Date:   Wed, 19 Jul 2023 17:22:09 -0700 (PDT)
From:   Stefano Stabellini <sstabellini@kernel.org>
To:     Oleksandr Tyshchenko <Oleksandr_Tyshchenko@epam.com>
cc:     Rahul Singh <rahul.singh@arm.com>,
        "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Juergen Gross <jgross@suse.com>,
        Stefano Stabellini <sstabellini@kernel.org>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Jane Malalane <jane.malalane@citrix.com>
Subject: Re: [PATCH v3] xen/evtchn: Introduce new IOCTL to bind static
 evtchn
In-Reply-To: <9a917f42-1a22-0c75-459e-db30c17dbe78@epam.com>
Message-ID: <alpine.DEB.2.22.394.2307191722010.3118466@ubuntu-linux-20-04-desktop>
References: <ae7329bf1713f83e4aad4f3fa0f316258c40a3e9.1689677042.git.rahul.singh@arm.com> <9a917f42-1a22-0c75-459e-db30c17dbe78@epam.com>
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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@arm.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@epam.com>

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