[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PATCH v6 2/3] xen/arm: Enable the existing x86 virtual PCI support for ARM.

  • To: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Fri, 15 Oct 2021 12:41:23 +0200
  • Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=suse.com; dmarc=pass action=none header.from=suse.com; dkim=pass header.d=suse.com; arc=none
  • Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=kaoPH3CTf7RBPOU2dtXrvzoOfvYv94QQZDguNdtAm/E=; b=MqmK9ulRZ+LYKq7PKoJLOD8wK+cVVie3l9iqB2mkhMa1DoN3+ZPv+vUVJVumHS3mb2O0pjTqiR7RhSaUXFuti4j6r16drJVdyAGzlGZ6nyDdDecBwliB8BOLlebXKxbicUlSt1y8sVHY1yG+3qdOqQ77YUFKB2elR8ubhRfdJQxmZ6kU83lbBN0q7j48T60B53UoERljRwlsjVf9HlR8i9vqNljEgNW8B89jWH9iVoJw7QQGjd0zIdWVCNdMmWS7bC9BC7HBQBZMkaqZKX+sSCWmadRiDUrjC0obH0NR4SUFyUCphZqnPNdStAFH5aLpnk8rDfBpHf2BjWXhEJ5LWA==
  • Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=J0c9navOkUScl9KwlSCVd77zbeDK/18QxBeEBsJCRRV5Q/yo66PopJ+qccsk10h+dqXeZmgGOem2rPVhVLydgUOatQ8SjXybVQVrSIvCP1Kf8lW/ynkTgQEY1KX81eFUo3/DAMwP7DGeN5AXGYhGg8IaZghs9EwDnDDcGXZiYFA3e4s4VeHmzIrII9yg57M6GC7O33R52Fw85iwJjIjGwcdpVTMaXEPo77HxTV4pxNTLXe5NrpU7MdnLlzx7M4LoFxFjOf680/hvtiRSZH4PPbCXKKFoMH9mUtHFFKIofnKUigwjdDtYw9U4Mh94lPxmKEi63mWDqoFu6eBah87C6w==
  • Authentication-results: citrix.com; dkim=none (message not signed) header.d=none;citrix.com; dmarc=none action=none header.from=suse.com;
  • Cc: Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Ian Jackson <iwj@xxxxxxxxxxxxxx>, Rahul Singh <Rahul.Singh@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Paul Durrant <paul@xxxxxxx>, Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>
  • Delivery-date: Fri, 15 Oct 2021 10:41:42 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 15.10.2021 12:33, Bertrand Marquis wrote:
>> On 15 Oct 2021, at 11:24, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>> On 15.10.2021 11:52, Bertrand Marquis wrote:
>>>> On 15 Oct 2021, at 09:32, Roger Pau Monné <roger.pau@xxxxxxxxxx> wrote:
>>>> On Thu, Oct 14, 2021 at 03:49:50PM +0100, Bertrand Marquis wrote:
>>>>> @@ -752,6 +752,19 @@ int pci_add_device(u16 seg, u8 bus, u8 devfn,
>>>>>    check_pdev(pdev);
>>>>> +#ifdef CONFIG_ARM
>>>>> +    /*
>>>>> +     * On ARM PCI devices discovery will be done by Dom0. Add vpci 
>>>>> handler when
>>>>> +     * Dom0 inform XEN to add the PCI devices in XEN.
>>>>> +     */
>>>>> +    ret = vpci_add_handlers(pdev);
>>>>> +    if ( ret )
>>>>> +    {
>>>>> +        printk(XENLOG_ERR "Setup of vPCI failed: %d\n", ret);
>>>>> +        goto out;
>>>>> +    }
>>>>> +#endif
>>>> I think vpci_add_handlers should be called after checking that
>>>> pdev->domain is != NULL, so I would move this chunk a bit below.
>>> On arm this would prevent the dom0less use case or to have the PCI
>>> bus enumerated from an other domain.
>>> @oleksandr: can you comment on this one, you might have a better
>>> answer than me on this ?
>> Well, without Xen doing the enumeration, some other entity would need
>> to do so, including the reporting to Xen. Obviously without a Dom0 it
>> would be ambiguous which domain to assign the device to; perhaps it
>> should be the caller in this case? That would make that caller domain
>> a pseudo-hwdom though, as far as PCI is concerned, which may not be
>> desirable according to my (limited) understanding of dom0less.
> This is not really related to this patch but the plan is the following:
> - enumeration would have to be done by the firmware or boot loader before
> - xen will have some code to detect PCI devices
> - dom0less can be used to assign PCI devices to guest
> Anyway does not change the fact that this must be called when domain is
> not NULL and I will fix that.

Since we now all seem to agree that the NULL would have been a problem,
may I ask in how far any of this has actually been tested?




Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.