From: "Roger Pau Monné" <roger.pau@citrix.com>
To: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
Cc: Jan Beulich <jbeulich@suse.com>,
"julien@xen.org" <julien@xen.org>,
"sstabellini@kernel.org" <sstabellini@kernel.org>,
Oleksandr Tyshchenko <Oleksandr_Tyshchenko@epam.com>,
Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
Artem Mygaiev <Artem_Mygaiev@epam.com>,
"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
"george.dunlap@citrix.com" <george.dunlap@citrix.com>,
"paul@xen.org" <paul@xen.org>,
Bertrand Marquis <bertrand.marquis@arm.com>,
Rahul Singh <rahul.singh@arm.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [PATCH v6 03/13] vpci: move lock outside of struct vpci
Date: Tue, 8 Feb 2022 14:38:42 +0100 [thread overview]
Message-ID: <YgJyYkrEGVduPVLg@Air-de-Roger> (raw)
In-Reply-To: <0f83fa71-c252-6e6c-47c9-3ef899b45901@epam.com>
On Tue, Feb 08, 2022 at 11:13:41AM +0000, Oleksandr Andrushchenko wrote:
>
>
> On 08.02.22 12:50, Roger Pau Monné wrote:
> > On Tue, Feb 08, 2022 at 07:35:34AM +0000, Oleksandr Andrushchenko wrote:
> >> 5. You name it
> >> ==============================================================
> >>
> >> From all the above I would recommend we go with option 2 which seems to reliably
> >> solve ABBA and does not bring cons of the other approaches.
> > 6. per-domain rwlock + per-device vpci lock
> >
> > Introduce vpci_header_write_lock(start, {end, size}) helper: return
> > whether a range requires the per-domain lock in write mode. This will
> > only return true if the range overlaps with the BAR ROM or the command
> > register.
> >
> > In vpci_{read,write}:
> >
> > if ( vpci_header_write_lock(...) )
> > /* Gain exclusive access to all of the domain pdevs vpci. */
> > write_lock(d->vpci);
> > else
> > {
> > read_lock(d->vpci);
> > spin_lock(vpci->lock);
> > }
> > ...
> >
> > The vpci assign/deassign functions would need to be modified to write
> > lock the per-domain rwlock. The MSI-X table MMIO handler will also
> > need to read lock the per domain vpci lock.
> Ok, so it seems you are in favor of this implementation and I have
> no objection as well. The only limitation we should be aware of is
> that once a path has acquired the read lock it is not possible to do
> any write path operations in there.
> vpci_process_pending will acquire write lock though as it can
> lead to vpci_remove_device on its error path.
>
> So, I am going to implement pdev->vpci->lock + d->vpci_lock
I think it's the less uncertain option.
As said, if you want to investigate whether you can successfully move
the checking into vpci_process_pending that would also be fine with
me, but I cannot assert it's going to be successful. OTOH I think the
per-domain rwlock + per-device spinlock seems quite likely to solve
our issues.
Thanks, Roger.
next prev parent reply other threads:[~2022-02-08 13:39 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-04 6:34 [PATCH v6 00/13] PCI devices passthrough on Arm, part 3 Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 01/13] xen/pci: arm: add stub for is_memory_hole Oleksandr Andrushchenko
2022-02-04 8:51 ` Julien Grall
2022-02-04 9:01 ` Oleksandr Andrushchenko
2022-02-04 9:41 ` Julien Grall
2022-02-04 9:47 ` Oleksandr Andrushchenko
2022-02-04 9:57 ` Julien Grall
2022-02-04 10:35 ` Oleksandr Andrushchenko
2022-02-04 11:00 ` Julien Grall
2022-02-04 11:25 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 02/13] rangeset: add RANGESETF_no_print flag Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 03/13] vpci: move lock outside of struct vpci Oleksandr Andrushchenko
2022-02-04 7:52 ` Jan Beulich
2022-02-04 8:13 ` Oleksandr Andrushchenko
2022-02-04 8:36 ` Jan Beulich
2022-02-04 8:58 ` Oleksandr Andrushchenko
2022-02-04 9:15 ` Jan Beulich
2022-02-04 10:12 ` Oleksandr Andrushchenko
2022-02-04 10:49 ` Jan Beulich
2022-02-04 11:13 ` Roger Pau Monné
2022-02-04 11:37 ` Jan Beulich
2022-02-04 12:37 ` Oleksandr Andrushchenko
2022-02-04 12:47 ` Jan Beulich
2022-02-04 12:53 ` Oleksandr Andrushchenko
2022-02-04 13:03 ` Jan Beulich
2022-02-04 13:06 ` Roger Pau Monné
2022-02-04 14:43 ` Oleksandr Andrushchenko
2022-02-04 14:57 ` Roger Pau Monné
2022-02-07 11:08 ` Oleksandr Andrushchenko
2022-02-07 12:34 ` Jan Beulich
2022-02-07 12:57 ` Oleksandr Andrushchenko
2022-02-07 13:02 ` Jan Beulich
2022-02-07 12:46 ` Roger Pau Monné
2022-02-07 13:53 ` Oleksandr Andrushchenko
2022-02-07 14:11 ` Jan Beulich
2022-02-07 14:27 ` Roger Pau Monné
2022-02-07 14:33 ` Jan Beulich
2022-02-07 14:35 ` Oleksandr Andrushchenko
2022-02-07 15:11 ` Oleksandr Andrushchenko
2022-02-07 15:26 ` Jan Beulich
2022-02-07 16:07 ` Oleksandr Andrushchenko
2022-02-07 16:15 ` Jan Beulich
2022-02-07 16:21 ` Oleksandr Andrushchenko
2022-02-07 16:37 ` Jan Beulich
2022-02-07 16:44 ` Oleksandr Andrushchenko
2022-02-08 7:35 ` Oleksandr Andrushchenko
2022-02-08 8:57 ` Jan Beulich
2022-02-08 9:03 ` Oleksandr Andrushchenko
2022-02-08 10:50 ` Roger Pau Monné
2022-02-08 11:13 ` Oleksandr Andrushchenko
2022-02-08 13:38 ` Roger Pau Monné [this message]
2022-02-08 13:52 ` Oleksandr Andrushchenko
2022-02-08 8:53 ` Jan Beulich
2022-02-08 9:00 ` Oleksandr Andrushchenko
2022-02-08 10:11 ` Roger Pau Monné
2022-02-08 10:32 ` Oleksandr Andrushchenko
2022-02-07 16:08 ` Roger Pau Monné
2022-02-07 16:12 ` Jan Beulich
2022-02-07 14:28 ` Oleksandr Andrushchenko
2022-02-07 14:19 ` Roger Pau Monné
2022-02-07 14:27 ` Oleksandr Andrushchenko
2022-02-04 11:37 ` Oleksandr Andrushchenko
2022-02-04 12:15 ` Roger Pau Monné
2022-02-04 10:57 ` Roger Pau Monné
2022-02-04 6:34 ` [PATCH v6 04/13] vpci: restrict unhandled read/write operations for guests Oleksandr Andrushchenko
2022-02-04 14:11 ` Jan Beulich
2022-02-04 14:24 ` Oleksandr Andrushchenko
2022-02-08 8:00 ` Oleksandr Andrushchenko
2022-02-08 9:04 ` Jan Beulich
2022-02-08 9:09 ` Oleksandr Andrushchenko
2022-02-08 9:05 ` Roger Pau Monné
2022-02-08 9:10 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 05/13] vpci: add hooks for PCI device assign/de-assign Oleksandr Andrushchenko
2022-02-07 16:28 ` Jan Beulich
2022-02-08 8:32 ` Oleksandr Andrushchenko
2022-02-08 9:13 ` Jan Beulich
2022-02-08 9:27 ` Oleksandr Andrushchenko
2022-02-08 9:44 ` Jan Beulich
2022-02-08 9:55 ` Oleksandr Andrushchenko
2022-02-08 10:09 ` Jan Beulich
2022-02-08 10:22 ` Oleksandr Andrushchenko
2022-02-08 10:29 ` Jan Beulich
2022-02-08 10:52 ` Oleksandr Andrushchenko
2022-02-08 11:00 ` Jan Beulich
2022-02-08 11:25 ` Oleksandr Andrushchenko
2022-02-10 8:21 ` Oleksandr Andrushchenko
2022-02-10 9:22 ` Jan Beulich
2022-02-10 9:33 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 06/13] vpci/header: implement guest BAR register handlers Oleksandr Andrushchenko
2022-02-07 17:06 ` Jan Beulich
2022-02-08 8:06 ` Oleksandr Andrushchenko
2022-02-08 9:16 ` Jan Beulich
2022-02-08 9:29 ` Roger Pau Monné
2022-02-08 9:25 ` Roger Pau Monné
2022-02-08 9:31 ` Oleksandr Andrushchenko
2022-02-08 9:48 ` Jan Beulich
2022-02-08 9:57 ` Oleksandr Andrushchenko
2022-02-08 10:15 ` Jan Beulich
2022-02-08 10:29 ` Oleksandr Andrushchenko
2022-02-08 13:58 ` Roger Pau Monné
2022-02-04 6:34 ` [PATCH v6 07/13] vpci/header: handle p2m range sets per BAR Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 08/13] vpci/header: program p2m with guest BAR view Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 09/13] vpci/header: emulate PCI_COMMAND register for guests Oleksandr Andrushchenko
2022-02-04 14:25 ` Jan Beulich
2022-02-08 8:13 ` Oleksandr Andrushchenko
2022-02-08 9:33 ` Jan Beulich
2022-02-08 9:38 ` Oleksandr Andrushchenko
2022-02-08 9:52 ` Jan Beulich
2022-02-08 9:58 ` Oleksandr Andrushchenko
2022-02-08 11:11 ` Roger Pau Monné
2022-02-08 11:29 ` Oleksandr Andrushchenko
2022-02-08 14:09 ` Roger Pau Monné
2022-02-08 14:13 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 10/13] vpci/header: reset the command register when adding devices Oleksandr Andrushchenko
2022-02-04 14:30 ` Jan Beulich
2022-02-04 14:37 ` Oleksandr Andrushchenko
2022-02-07 7:29 ` Jan Beulich
2022-02-07 11:27 ` Oleksandr Andrushchenko
2022-02-07 12:38 ` Jan Beulich
2022-02-07 12:51 ` Oleksandr Andrushchenko
2022-02-07 12:54 ` Jan Beulich
2022-02-07 14:17 ` Oleksandr Andrushchenko
2022-02-07 14:31 ` Jan Beulich
2022-02-07 14:46 ` Oleksandr Andrushchenko
2022-02-07 15:05 ` Jan Beulich
2022-02-07 15:14 ` Oleksandr Andrushchenko
2022-02-07 15:28 ` Jan Beulich
2022-02-07 15:59 ` Oleksandr Andrushchenko
2022-02-10 12:54 ` Oleksandr Andrushchenko
2022-02-10 13:36 ` Jan Beulich
2022-02-10 13:56 ` Oleksandr Andrushchenko
2022-02-10 12:59 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 11/13] vpci: add initial support for virtual PCI bus topology Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 12/13] xen/arm: translate virtual PCI bus topology for guests Oleksandr Andrushchenko
2022-02-04 7:56 ` Jan Beulich
2022-02-04 8:18 ` Oleksandr Andrushchenko
2022-02-04 6:34 ` [PATCH v6 13/13] xen/arm: account IO handlers for emulated PCI MSI-X Oleksandr Andrushchenko
2022-02-11 15:28 ` Julien Grall
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