From: Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
To: Julien Grall <julien@xen.org>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "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>,
"jbeulich@suse.com" <jbeulich@suse.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>,
Oleksandr Andrushchenko <Oleksandr_Andrushchenko@epam.com>
Subject: Re: [PATCH v6 2/7] xen/arm: add pci-domain for disabled devices
Date: Thu, 18 Nov 2021 07:13:26 +0000 [thread overview]
Message-ID: <072848c8-54da-cb73-3b8a-0c35826cc812@epam.com> (raw)
In-Reply-To: <ab95fc39-d1b2-be80-8245-85161a8271e1@xen.org>
Hi, Julien!
On 17.11.21 23:33, Julien Grall wrote:
> Hi Oleksandr,
>
> On 17/11/2021 06:56, Oleksandr Andrushchenko wrote:
>> Hi, Julien!
>>
>> On 16.11.21 20:48, Julien Grall wrote:
>>> Hi Oleksander,
>>>
>>> On 05/11/2021 06:33, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>>>
>>>> If a PCI host bridge device is present in the device tree, but is
>>>> disabled, then its PCI host bridge driver was not instantiated.
>>>> This results in the failure of the pci_get_host_bridge_segment()
>>>> and the following panic during Xen start:
>>>>
>>>> (XEN) Device tree generation failed (-22).
>>>> (XEN)
>>>> (XEN) ****************************************
>>>> (XEN) Panic on CPU 0:
>>>> (XEN) Could not set up DOM0 guest OS
>>>> (XEN) ****************************************
>>>>
>>>> Fix this by adding "linux,pci-domain" property for all device tree nodes
>>>> which have "pci" device type, so we know which segments will be used by
>>>> the guest for which bridges.
>>>>
>>>> Fixes: 4cfab4425d39 ("xen/arm: Add linux,pci-domain property for hwdom if not available.")
>>>>
>>>> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>>>>
>>>> ---
>>>> New in v6
>>>> ---
>>>> xen/arch/arm/domain_build.c | 15 ++++++++++++++-
>>>> xen/arch/arm/pci/pci-host-common.c | 2 +-
>>>> xen/include/asm-arm/pci.h | 8 ++++++++
>>>> 3 files changed, 23 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>>>> index 491f5e2c316e..f7fcb1400c19 100644
>>>> --- a/xen/arch/arm/domain_build.c
>>>> +++ b/xen/arch/arm/domain_build.c
>>>> @@ -753,9 +753,22 @@ static int __init write_properties(struct domain *d, struct kernel_info *kinfo,
>>>> {
>>>> uint16_t segment;
>>>> + /*
>>>> + * The node doesn't have "linux,pci-domain" property and it is
>>>> + * possible that:
>>>> + * - Xen only has drivers for a part of the host bridges
>>>> + * - some host bridges are disabled
>>>> + * Make sure we insert the correct "linux,pci-domain" property
>>>> + * in any case, so we know which segments will be used
>>>> + * by Linux for which bridges.
>>>
>>> The check above will check the node type is "pci". AFAICT, this would also cover PCI devices. I am not aware of any issue to add "linux,pci-domain" for them. However, this feels a bit odd.
>>>
>>> From my understanding, a PCI device would always be described as a child of the hostbridges. So I would rework the 'if' to also check if the parent type is not "pci".
>>>
>> We may have "bridge -> bridge -> device" topology as well.
>
> Do you have an example of Device-Tree?
No, I don't have at hand, but I can imagine this can relatively easy be done with QEMU
Even if not, do you assume this topology can never happen?
>
>> So, I prefer to have the check as it is.
>
> I don't really like the idea to spuriously add "linux,pci-domain" to PCI DT node. But if there are no other solution, then this should at least be mentionned in the commit message and code.
I am fine with any solution here, I just want that to be defined and implemented.
Please let me know the final decision on this and how we proceed
>
> [...]
>
>> Yes, this sounds reasonable, I will add this change and print an error message so it is
>> easier to understand what Xen doesn't like (it took me a while to debug and understand
>> why I have "(XEN) Device tree generation failed (-22).")
>
>
> Sounds good to me. The current error is indeed confusing.
>
> Cheers,
>
Thank you,
Oleksandr
next prev parent reply other threads:[~2021-11-18 7:14 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-05 6:33 [PATCH v6 0/7] PCI devices passthrough on Arm, part 2 Oleksandr Andrushchenko
2021-11-05 6:33 ` [PATCH v6 1/7] xen/arm: rename DEVICE_PCI to DEVICE_PCI_HOSTBRIDGE Oleksandr Andrushchenko
2021-11-16 18:26 ` Julien Grall
2021-11-05 6:33 ` [PATCH v6 2/7] xen/arm: add pci-domain for disabled devices Oleksandr Andrushchenko
2021-11-16 18:48 ` Julien Grall
2021-11-17 6:56 ` Oleksandr Andrushchenko
2021-11-17 21:33 ` Julien Grall
2021-11-18 7:13 ` Oleksandr Andrushchenko [this message]
2021-11-22 15:29 ` Julien Grall
2021-11-22 16:23 ` Oleksandr Andrushchenko
2021-11-22 17:17 ` Julien Grall
2021-11-23 6:31 ` Oleksandr Andrushchenko
2021-11-23 16:05 ` Julien Grall
2021-11-23 16:44 ` Oleksandr Andrushchenko
2021-11-23 17:15 ` Julien Grall
2021-11-24 6:54 ` Oleksandr Andrushchenko
2021-11-05 6:33 ` [PATCH v6 3/7] xen/arm: setup MMIO range trap handlers for hardware domain Oleksandr Andrushchenko
2021-11-09 9:20 ` Oleksandr Andrushchenko
2021-11-16 19:12 ` Julien Grall
2021-11-18 7:27 ` Oleksandr Andrushchenko
2021-11-18 10:46 ` Oleksandr Andrushchenko
2021-11-22 17:36 ` Julien Grall
2021-11-23 6:58 ` Oleksandr Andrushchenko
2021-11-23 16:12 ` Julien Grall
2021-11-23 16:41 ` Oleksandr Andrushchenko
2021-11-23 16:58 ` Julien Grall
2021-11-24 7:22 ` Oleksandr Andrushchenko
2021-11-05 6:33 ` [PATCH v6 4/7] xen/arm: do not map PCI ECAM and MMIO space to Domain-0's p2m Oleksandr Andrushchenko
2021-11-23 16:42 ` Julien Grall
2021-11-24 7:42 ` Oleksandr Andrushchenko
2021-11-05 6:33 ` [PATCH v6 5/7] xen/arm: do not map IRQs and memory for disabled devices Oleksandr Andrushchenko
2021-11-16 19:22 ` Julien Grall
2021-11-18 6:59 ` Oleksandr Andrushchenko
2021-11-22 19:31 ` Julien Grall
2021-11-23 7:23 ` Oleksandr Andrushchenko
2021-11-05 6:33 ` [PATCH v6 6/7] xen/arm: process pending vPCI map/unmap operations Oleksandr Andrushchenko
2021-11-05 7:40 ` Jan Beulich
2021-11-17 21:26 ` Julien Grall
2021-11-05 6:33 ` [PATCH v6 7/7] xen/arm: do not use void pointer in pci_host_common_probe Oleksandr Andrushchenko
2021-11-17 11:12 ` Rahul Singh
2021-11-17 21:45 ` Julien Grall
2021-11-18 7:34 ` Oleksandr Andrushchenko
2021-11-22 17:48 ` Julien Grall
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