From: Jan Beulich <jbeulich@suse.com>
To: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
Cc: "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>,
"roger.pau@citrix.com" <roger.pau@citrix.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 05/13] vpci: add hooks for PCI device assign/de-assign
Date: Tue, 8 Feb 2022 10:13:12 +0100 [thread overview]
Message-ID: <582ee8f9-7b01-4adc-6a8a-ce8b1dffd534@suse.com> (raw)
In-Reply-To: <3fe6dbe3-51c6-f87f-23f9-cf2e1a924326@epam.com>
On 08.02.2022 09:32, Oleksandr Andrushchenko wrote:
> On 07.02.22 18:28, Jan Beulich wrote:
>> On 04.02.2022 07:34, Oleksandr Andrushchenko wrote:
>>> @@ -1507,6 +1511,8 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
>>> pci_to_dev(pdev), flag);
>>> }
>>>
>>> + rc = vpci_assign_device(d, pdev);
>>> +
>>> done:
>>> if ( rc )
>>> printk(XENLOG_G_WARNING "%pd: assign (%pp) failed (%d)\n",
>> There's no attempt to undo anything in the case of getting back an
>> error. ISTR this being deemed okay on the basis that the tool stack
>> would then take whatever action, but whatever it is that is supposed
>> to deal with errors here wants spelling out in the description.
> Why? I don't change the previously expected decision and implementation
> of the assign_device function: I use error paths as they were used before
> for the existing code. So, I see no clear reason to stress that the existing
> and new code relies on the toolstack
Saying half a sentence on this is helping review.
>> What's important is that no caller up the call tree may be left with
>> the impression that the device is still owned by the original
>> domain. With how you have it, the device is going to be owned by the
>> new domain, but not really usable.
> This is not true: vpci_assign_device will call vpci_deassign_device
> internally if it fails. So, the device won't be assigned in this case
No. The device is assigned to whatever pdev->domain holds. Calling
vpci_deassign_device() there merely makes sure that the device will
have _no_ vPCI data and hooks in place, rather than something
partial.
>>> --- a/xen/drivers/vpci/vpci.c
>>> +++ b/xen/drivers/vpci/vpci.c
>>> @@ -99,6 +99,33 @@ int vpci_add_handlers(struct pci_dev *pdev)
>>>
>>> return rc;
>>> }
>>> +
>>> +#ifdef CONFIG_HAS_VPCI_GUEST_SUPPORT
>>> +/* Notify vPCI that device is assigned to guest. */
>>> +int vpci_assign_device(struct domain *d, struct pci_dev *pdev)
>>> +{
>>> + int rc;
>>> +
>>> + if ( !has_vpci(d) )
>>> + return 0;
>>> +
>>> + rc = vpci_add_handlers(pdev);
>>> + if ( rc )
>>> + vpci_deassign_device(d, pdev);
>>> +
>>> + return rc;
>>> +}
>>> +
>>> +/* Notify vPCI that device is de-assigned from guest. */
>>> +void vpci_deassign_device(struct domain *d, struct pci_dev *pdev)
>>> +{
>>> + if ( !has_vpci(d) )
>>> + return;
>>> +
>>> + vpci_remove_device(pdev);
>>> +}
>>> +#endif /* CONFIG_HAS_VPCI_GUEST_SUPPORT */
>> While for the latter function you look to need two parameters, do you
>> really need them also in the former one?
> Do you mean instead of passing d we could just use pdev->domain?
> int vpci_assign_device(struct pci_dev *pdev)
> +{
> + int rc;
> +
> + if ( !has_vpci(pdev->domain) )
> + return 0;
Yes.
> Yes, we probably can, but the rest of functions called from assign_device
> are accepting both d and pdev, so not sure why would we want these
> two be any different. Any good reason not to change others as well then?
Yes: Prior to the call of the ->assign_device() hook, d != pdev->domain.
It is the _purpose_ of this function to change ownership of the device.
Jan
next prev parent reply other threads:[~2022-02-08 9:13 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
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 [this message]
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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