linux-kernel - Re: [PATCH v8 07/10] iommufd: Fault-capable hwpt attach/detach/replace

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Message-ID: <e030bf31-330c-4734-be13-634174c7b099@linux.intel.com>
Date: Sun, 27 Oct 2024 22:26:03 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Zhangfei Gao <zhangfei.gao@...aro.org>
Cc: baolu.lu@...ux.intel.com, Jason Gunthorpe <jgg@...pe.ca>,
 Kevin Tian <kevin.tian@...el.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Nicolin Chen <nicolinc@...dia.com>, Yi Liu <yi.l.liu@...el.com>,
 Jacob Pan <jacob.jun.pan@...ux.intel.com>,
 Joel Granados <j.granados@...sung.com>, iommu@...ts.linux.dev,
 virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
 Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>
Subject: Re: [PATCH v8 07/10] iommufd: Fault-capable hwpt
 attach/detach/replace

On 2024/10/27 22:12, Zhangfei Gao wrote:
> On Fri, 18 Oct 2024 at 10:45, Zhangfei Gao<zhangfei.gao@...aro.org> wrote:
>> Hi, Baolu
>>
>> On Fri, 18 Oct 2024 at 09:58, Baolu Lu<baolu.lu@...ux.intel.com> wrote:
>>> On 2024/10/17 21:08, Jason Gunthorpe wrote:
>>>> On Thu, Oct 17, 2024 at 08:35:24PM +0800, Zhangfei Gao wrote:
>>>>
>>>>> Yes, you are right
>>>>>    I am using SRIOV vf and stall feature, so is_virtfn == true
>>>>>
>>>>> Our ACC devices are fake pci endpoint devices which supports stall,
>>>>> And they also supports sriov
>>>>>
>>>>> So I have to ignore the limitation.
>>>> I see, so that is more complicated.
>>>>
>>>> Lu, what do you think about also checking if the PCI function has PRI
>>>> ? If not PRI assume the fault is special and doesn't follow PRI rules?
>>>>
>>>> Or maybe we can have the iommu driver tag the event as a PRI/not-PRI
>>>> fault?
>>> This limitation applies to PRI on PCI/SRIOV VFs because the PRI might be
>>> a shared resource and current iommu subsystem is not ready to support
>>> enabling/disabling PRI on a VF without any impact on others.
>>>
>>> In my understanding, it's fine to remove this limitation from the use
>>> case of non-PRI on SRIOV VFs. Perhaps something like below?
>>>
>> #include <linux/pci-ats.h>
>>>          if (dev_is_pci(dev)) {
>>>                  struct pci_dev *pdev = to_pci_dev(dev);
>>>                  if (pdev->is_virtfn && pci_pri_supported(pdev))
>>>                          return -EINVAL;
>>>          }
>> Yes, this works on our platform.
> Will you send this patch?
> 
> Tested-by: Zhangfei Gao<zhangfei.gao@...aro.org>

Can you please make this change a formal patch by yourself? As I don't
have hardware in hand, I'm not confident to accurately describe the
requirement or verify the new version during the upstream process.

Thanks,
baolu