From: Lu Baolu <baolu.lu@linux.intel.com>
To: Robin Murphy <robin.murphy@arm.com>, joro@8bytes.org, will@kernel.org
Cc: jean-philippe@linaro.org, zhang.lyra@gmail.com,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
thierry.reding@gmail.com, gerald.schaefer@linux.ibm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 02/13] iommu: Move bus setup to IOMMU device registration
Date: Sat, 23 Apr 2022 17:41:05 +0800 [thread overview]
Message-ID: <48744abf-bd9b-927d-9ca3-a3e4bdc07fbb@linux.intel.com> (raw)
In-Reply-To: <60d6a35e-5d12-b8c2-b0d2-7155965a10e5@linux.intel.com>
On 2022/4/23 17:00, Lu Baolu wrote:
> On 2022/4/23 16:51, Lu Baolu wrote:
>> On 2022/4/23 16:37, Robin Murphy wrote:
>>> On 2022-04-23 09:01, Lu Baolu wrote:
>>>> Hi Robin,
>>>>
>>>> On 2022/4/19 15:20, Robin Murphy wrote:
>>>>> On 2022-04-19 00:37, Lu Baolu wrote:
>>>>>> On 2022/4/19 6:09, Robin Murphy wrote:
>>>>>>> On 2022-04-16 01:04, Lu Baolu wrote:
>>>>>>>> On 2022/4/14 20:42, Robin Murphy wrote:
>>>>>>>>> @@ -1883,27 +1900,12 @@ static int iommu_bus_init(struct
>>>>>>>>> bus_type *bus)
>>>>>>>>> */
>>>>>>>>> int bus_set_iommu(struct bus_type *bus, const struct
>>>>>>>>> iommu_ops *ops)
>>>>>>>>> {
>>>>>>>>> - int err;
>>>>>>>>> -
>>>>>>>>> - if (ops == NULL) {
>>>>>>>>> - bus->iommu_ops = NULL;
>>>>>>>>> - return 0;
>>>>>>>>> - }
>>>>>>>>> -
>>>>>>>>> - if (bus->iommu_ops != NULL)
>>>>>>>>> + if (bus->iommu_ops && ops && bus->iommu_ops != ops)
>>>>>>>>> return -EBUSY;
>>>>>>>>> bus->iommu_ops = ops;
>>>>>>>>
>>>>>>>> Do we still need to keep above lines in bus_set_iommu()?
>>>>>>>
>>>>>>> It preserves the existing behaviour until each callsite and its
>>>>>>> associated error handling are removed later on, which seems like
>>>>>>> as good a thing to do as any. Since I'm already relaxing
>>>>>>> iommu_device_register() to a warn-but-continue behaviour while it
>>>>>>> keeps the bus ops on life-support internally, I figured not
>>>>>>> changing too much at once would make it easier to bisect any
>>>>>>> potential issues arising from this first step.
>>>>>>
>>>>>> Fair enough. Thank you for the explanation.
>>>>>>
>>>>>> Do you have a public tree that I could pull these patches and try
>>>>>> them
>>>>>> on an Intel hardware? Or perhaps you have done this? I like the whole
>>>>>> idea of this series, but it's better to try it with a real hardware.
>>>>>
>>>>> I haven't bothered with separate branches since there's so many
>>>>> different pieces in-flight, but my complete (unstable) development
>>>>> branch can be found here:
>>>>>
>>>>> https://gitlab.arm.com/linux-arm/linux-rm/-/commits/iommu/bus
>>>>>
>>>>> For now I'd recommend winding the head back to "iommu: Clean up
>>>>> bus_set_iommu()" for testing - some of the patches above that have
>>>>> already been posted and picked up by their respective subsystems,
>>>>> but others are incomplete and barely compile-tested. I'll probably
>>>>> rearrange it later this week to better reflect what's happened so far.
>>>>
>>>> I wound the head back to "iommu: Clean up bus_set_iommu" and tested it
>>>> on an Intel machine. It got stuck during boot. This test was on a
>>>> remote
>>>> machine and I have no means to access it physically. So I can't get any
>>>> kernel debugging messages. (I have to work from home these days. :-()
>>>>
>>>> I guess it's due to the fact that intel_iommu_probe_device() callback
>>>> only works for the pci devices. The issue occurs when probing a device
>>>> other than a PCI one.
>>>
>>> Yeah, I was wondering if that would be significant, since it's the
>>> only driver that never registered itself for platform_bus_type so
>>> won't have actually seen those calls before. I'm inclined to bodge
>>> that as below for now, as long as it then works OK in terms of the
>>> rest of the changes.
>>>
>>> Thanks,
>>> Robin.
>>>
>>> ----->8-----
>>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>>> index 9fa1b98186a3..6e359f92ec00 100644
>>> --- a/drivers/iommu/intel/iommu.c
>>> +++ b/drivers/iommu/intel/iommu.c
>>> @@ -4565,6 +4565,10 @@ static struct iommu_device
>>> *intel_iommu_probe_device(struct device *dev)
>>> unsigned long flags;
>>> u8 bus, devfn;
>>>
>>> + /* ANDD platform device support needs fixing */
>>> + if (!pdev)
>>> + return ERR_PTR(-ENODEV);
>>> +
>>> iommu = device_to_iommu(dev, &bus, &devfn);
>>> if (!iommu)
>>> return ERR_PTR(-ENODEV);
>>
>> I haven't seen any real ANDD platform devices, hence this works for me.
>
> Or more precisely, return NULL when @dev goes through device_to_iommu()?
>
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index df5c62ecf942..0d447739e076 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -797,8 +797,11 @@ struct intel_iommu *device_to_iommu(struct device
> *dev, u8 *bus, u8 *devfn)
> pf_pdev = pci_physfn(pdev);
> dev = &pf_pdev->dev;
> segment = pci_domain_nr(pdev->bus);
> - } else if (has_acpi_companion(dev))
> + } else if (has_acpi_companion(dev)) {
> dev = &ACPI_COMPANION(dev)->dev;
> + } else {
> + return NULL;
> + }
>
> rcu_read_lock();
> for_each_iommu(iommu, drhd) {
Robin, please ignore this. "has_acpi_companion(dev)" isn't equal to an
ANDD device. Please use yours. Sorry for the noise.
Best regards,
baolu
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next prev parent reply other threads:[~2022-04-23 9:42 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20220414124252eucas1p1f2d8689ef5d281ea70d619888108d2fe@eucas1p1.samsung.com>
2022-04-14 12:42 ` [PATCH 00/13] iommu: Retire bus_set_iommu() Robin Murphy
2022-04-14 12:42 ` [PATCH 01/13] iommu: Always register bus notifiers Robin Murphy
2022-04-14 12:42 ` [PATCH 02/13] iommu: Move bus setup to IOMMU device registration Robin Murphy
2022-04-16 0:04 ` Lu Baolu
2022-04-18 22:09 ` Robin Murphy
2022-04-18 23:37 ` Lu Baolu
2022-04-19 7:20 ` Robin Murphy
2022-04-19 10:13 ` Lu Baolu
2022-04-23 8:01 ` Lu Baolu
2022-04-23 8:37 ` Robin Murphy
2022-04-23 8:51 ` Lu Baolu
2022-04-23 9:00 ` Lu Baolu
2022-04-23 9:41 ` Lu Baolu [this message]
2022-04-22 18:37 ` Krishna Reddy
2022-04-22 19:02 ` Robin Murphy
2022-04-14 12:42 ` [PATCH 03/13] iommu/amd: Clean up bus_set_iommu() Robin Murphy
2022-04-14 12:42 ` [PATCH 04/13] iommu/arm-smmu: " Robin Murphy
2022-04-19 14:40 ` Will Deacon
2022-04-20 16:05 ` Robin Murphy
2022-04-21 8:33 ` Will Deacon
2022-04-14 12:42 ` [PATCH 05/13] iommu/arm-smmu-v3: " Robin Murphy
2022-04-19 14:42 ` Will Deacon
2022-04-14 12:42 ` [PATCH 06/13] iommu/dart: " Robin Murphy
2022-04-15 14:28 ` Sven Peter
2022-04-14 12:42 ` [PATCH 07/13] iommu/exynos: " Robin Murphy
2022-04-14 12:42 ` [PATCH 08/13] iommu/ipmmu-vmsa: " Robin Murphy
2022-04-14 12:42 ` [PATCH 09/13] iommu/mtk: " Robin Murphy
2022-04-14 12:42 ` [PATCH 10/13] iommu/omap: " Robin Murphy
2022-04-14 12:42 ` [PATCH 11/13] iommu/tegra-smmu: " Robin Murphy
2022-04-14 12:42 ` [PATCH 12/13] iommu/virtio: " Robin Murphy
2022-04-21 17:12 ` Jean-Philippe Brucker
2022-04-21 19:44 ` Robin Murphy
2022-04-14 12:42 ` [PATCH 13/13] iommu: " Robin Murphy
2022-04-14 21:00 ` [PATCH 00/13] iommu: Retire bus_set_iommu() Marek Szyprowski
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