From: "Michael S. Tsirkin" <mst@redhat.com>
To: Gleb Natapov <gleb@scylladb.com>
Cc: Avi Kivity <avi@scylladb.com>,
Alex Williamson <alex.williamson@redhat.com>,
Vlad Zolotarov <vladz@cloudius-systems.com>,
Greg KH <gregkh@linuxfoundation.org>,
linux-kernel@vger.kernel.org, hjk@hansjkoch.de, corbet@lwn.net,
bruce.richardson@intel.com, avi@cloudius-systems.com,
gleb@cloudius-systems.com, stephen@networkplumber.org,
alexander.duyck@gmail.com
Subject: Re: [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support
Date: Thu, 8 Oct 2015 15:15:20 +0300 [thread overview]
Message-ID: <20151008151147-mutt-send-email-mst@redhat.com> (raw)
In-Reply-To: <20151008094508.GH11716@scylladb.com>
On Thu, Oct 08, 2015 at 12:45:08PM +0300, Gleb Natapov wrote:
> On Thu, Oct 08, 2015 at 12:38:28PM +0300, Michael S. Tsirkin wrote:
> > On Thu, Oct 08, 2015 at 10:59:10AM +0300, Gleb Natapov wrote:
> > > I do not remember this been an issue when uio_generic was accepted
> > > into the kernel. The reason was because it meant to be accessible by root
> > > only.
> >
> > No - because it does not need bus mastering. So it can be used safely
> > with some devices.
> >
> It still can be used safely with same devices.
This patch does not add any functionality that can be used safely.
And for no good reason except it's a hassle.
> Admittedly I did not look
> close, but I am sure the patch does not enable bus mastering if MSI
> interrupt is not requested. If not, well that can be fixed. But more
> importantly it can be used unsafely in its current state. Not only can,
> it is widely used so.
>
> > [mst@robin linux]$ git grep pci_set_master|wc -l 533
> > [mst@robin linux]$ git grep pci_enable|wc -l 1597
> >
> > Looks like about 2/3 devices don't need to be bus masters.
> >
> > It's up to admin not to bind it to devices, and that is unfortunate,
> > but manually binding an incorrect driver to a device is generally
> > a hard problem to solve.
> >
> > > > There's also drivers/vfio/virqfd.c which deals
> > > > with sending interrupts over eventfds correctly.
> > > >
> > > As opposite to this patch that deals with them incorrectly? In what way?
> >
> > cleanup on fd close is not handled.
> >
> Have you commented about this on the patch and it was not fixed?
No - I only noticed this when I poked at VFIO to try and explain
why it's not a good idea to duplicate its code. I'm sure there
are more issues that we'll just have to re-discover the hard way
if we do try.
> --
> Gleb.
next prev parent reply other threads:[~2015-10-08 12:15 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-04 20:43 [PATCH v3 0/3] uio: add MSI/MSI-X support to uio_pci_generic driver Vlad Zolotarov
2015-10-04 20:43 ` [PATCH v3 1/3] uio: add ioctl support Vlad Zolotarov
2015-10-05 3:03 ` Greg KH
2015-10-05 7:33 ` Vlad Zolotarov
2015-10-05 8:01 ` Greg KH
2015-10-05 10:36 ` Vlad Zolotarov
2015-10-05 20:02 ` Michael S. Tsirkin
[not found] ` <CAOYyTHZ2=UCYxuJKvd5S6qxp=84DBq5bMadg5wL0rFLZBh2-8Q@mail.gmail.com>
2015-10-05 22:29 ` Michael S. Tsirkin
2015-10-06 8:33 ` Vlad Zolotarov
2015-10-06 14:19 ` Michael S. Tsirkin
2015-10-06 14:30 ` Gleb Natapov
2015-10-06 15:19 ` Michael S. Tsirkin
2015-10-06 15:31 ` Vlad Zolotarov
2015-10-06 15:57 ` Gleb Natapov
2015-10-04 20:43 ` [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support Vlad Zolotarov
2015-10-05 3:11 ` Greg KH
2015-10-05 7:41 ` Vlad Zolotarov
2015-10-05 7:56 ` Greg KH
2015-10-05 10:48 ` Vlad Zolotarov
2015-10-05 10:57 ` Greg KH
2015-10-05 11:09 ` Avi Kivity
2015-10-05 13:08 ` Greg KH
2015-10-05 11:41 ` Vlad Zolotarov
2015-10-05 11:47 ` Avi Kivity
2015-10-05 11:53 ` Vlad Zolotarov
2015-10-05 8:28 ` Avi Kivity
2015-10-05 9:49 ` Greg KH
2015-10-05 10:20 ` Avi Kivity
2015-10-06 14:38 ` Michael S. Tsirkin
2015-10-06 14:43 ` Vlad Zolotarov
2015-10-06 14:56 ` Michael S. Tsirkin
2015-10-06 15:23 ` Avi Kivity
2015-10-06 18:51 ` Alex Williamson
2015-10-06 21:32 ` Stephen Hemminger
2015-10-06 21:41 ` Alex Williamson
[not found] ` <CAOaVG152OrQz-Bbnpr0VeE+vLH7nMGsG6A3sD7eTQHormNGVUg@mail.gmail.com>
2015-10-07 7:57 ` Vlad Zolotarov
[not found] ` <5614C160.6000203@scylladb.com>
2015-10-07 8:00 ` Vlad Zolotarov
2015-10-07 8:01 ` Vlad Zolotarov
2015-10-07 6:52 ` Avi Kivity
2015-10-07 16:31 ` Alex Williamson
2015-10-07 16:39 ` Avi Kivity
2015-10-07 21:05 ` Michael S. Tsirkin
2015-10-08 4:19 ` Gleb Natapov
2015-10-08 7:41 ` Michael S. Tsirkin
2015-10-08 7:59 ` Gleb Natapov
2015-10-08 9:38 ` Michael S. Tsirkin
2015-10-08 9:45 ` Gleb Natapov
2015-10-08 12:15 ` Michael S. Tsirkin [this message]
2015-10-08 5:33 ` Avi Kivity
2015-10-08 7:32 ` Michael S. Tsirkin
2015-10-08 8:46 ` Avi Kivity
2015-10-08 9:16 ` Michael S. Tsirkin
2015-10-08 9:44 ` Avi Kivity
2015-10-08 12:06 ` Michael S. Tsirkin
2015-10-08 12:27 ` Gleb Natapov
2015-10-08 13:20 ` Michael S. Tsirkin
2015-10-08 13:28 ` Gleb Natapov
2015-10-08 16:43 ` Michael S. Tsirkin
2015-10-08 17:01 ` Gleb Natapov
2015-10-08 17:39 ` Michael S. Tsirkin
2015-10-08 17:53 ` Gleb Natapov
2015-10-08 18:38 ` Greg KH
2015-10-08 8:32 ` Michael S. Tsirkin
2015-10-08 8:52 ` Gleb Natapov
2015-10-08 9:19 ` Avi Kivity
2015-10-08 10:26 ` Michael S. Tsirkin
2015-10-08 13:20 ` Avi Kivity
2015-10-08 14:17 ` Michael S. Tsirkin
2015-10-08 15:31 ` Alex Williamson
2015-10-07 20:05 ` Michael S. Tsirkin
2015-10-07 7:55 ` Vlad Zolotarov
2015-10-08 8:48 ` Michael S. Tsirkin
2015-10-06 15:28 ` Vlad Zolotarov
2015-10-06 14:46 ` Michael S. Tsirkin
2015-10-06 15:27 ` Avi Kivity
2015-10-05 8:41 ` Stephen Hemminger
2015-10-05 9:08 ` Vlad Zolotarov
2015-10-05 10:06 ` Vlad Zolotarov
2015-10-05 20:09 ` Michael S. Tsirkin
2015-10-05 9:11 ` Vlad Zolotarov
2015-10-05 19:16 ` Michael S. Tsirkin
2015-10-04 20:43 ` [PATCH v3 3/3] Documentation: update uio-howto Vlad Zolotarov
2015-10-04 20:45 ` [PATCH v3 0/3] uio: add MSI/MSI-X support to uio_pci_generic driver Vlad Zolotarov
2015-10-05 19:50 ` Michael S. Tsirkin
2015-10-06 8:37 ` Vlad Zolotarov
2015-10-06 14:30 ` Michael S. Tsirkin
2015-10-06 14:40 ` Vlad Zolotarov
2015-10-06 15:13 ` Michael S. Tsirkin
2015-10-06 16:35 ` Vlad Zolotarov
2015-10-06 15:11 ` Avi Kivity
2015-10-06 15:15 ` Michael S. Tsirkin
2015-10-06 16:00 ` Gleb Natapov
2015-10-06 16:09 ` Avi Kivity
2015-10-07 10:25 ` Michael S. Tsirkin
2015-10-07 10:28 ` Avi Kivity
-- strict thread matches above, loose matches on Subject: below --
2015-10-04 20:39 Vlad Zolotarov
2015-10-04 20:39 ` [PATCH v3 2/3] uio_pci_generic: add MSI/MSI-X support Vlad Zolotarov
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