From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: baolu.lu@linux.intel.com, Christoph Hellwig <hch@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Joerg Roedel <joro@8bytes.org>,
Alex Williamson <alex.williamson@redhat.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Kevin Tian <kevin.tian@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Chaitanya Kulkarni <kch@nvidia.com>,
kvm@vger.kernel.org, rafael@kernel.org,
linux-pci@vger.kernel.org, Cornelia Huck <cohuck@redhat.com>,
linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org,
Jacob jun Pan <jacob.jun.pan@intel.com>,
Diana Craciun <diana.craciun@oss.nxp.com>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH 01/11] iommu: Add device dma ownership set/release interfaces
Date: Thu, 18 Nov 2021 09:12:41 +0800 [thread overview]
Message-ID: <5901c54b-a6eb-b060-aa52-15de7708d703@linux.intel.com> (raw)
In-Reply-To: <20211117133517.GJ2105516@nvidia.com>
On 11/17/21 9:35 PM, Jason Gunthorpe wrote:
> On Wed, Nov 17, 2021 at 01:22:19PM +0800, Lu Baolu wrote:
>> Hi Jason,
>>
>> On 11/16/21 9:46 PM, Jason Gunthorpe wrote:
>>> On Tue, Nov 16, 2021 at 09:57:30AM +0800, Lu Baolu wrote:
>>>> Hi Christoph,
>>>>
>>>> On 11/15/21 9:14 PM, Christoph Hellwig wrote:
>>>>> On Mon, Nov 15, 2021 at 10:05:42AM +0800, Lu Baolu wrote:
>>>>>> +enum iommu_dma_owner {
>>>>>> + DMA_OWNER_NONE,
>>>>>> + DMA_OWNER_KERNEL,
>>>>>> + DMA_OWNER_USER,
>>>>>> +};
>>>>>> +
>>>>>
>>>>>> + enum iommu_dma_owner dma_owner;
>>>>>> + refcount_t owner_cnt;
>>>>>> + struct file *owner_user_file;
>>>>>
>>>>> I'd just overload the ownership into owner_user_file,
>>>>>
>>>>> NULL -> no owner
>>>>> (struct file *)1UL) -> kernel
>>>>> real pointer -> user
>>>>>
>>>>> Which could simplify a lot of the code dealing with the owner.
>>>>>
>>>>
>>>> Yeah! Sounds reasonable. I will make this in the next version.
>>>
>>> It would be good to figure out how to make iommu_attach_device()
>>> enforce no other driver binding as a kernel user without a file *, as
>>> Robin pointed to, before optimizing this.
>>>
>>> This fixes an existing bug where iommu_attach_device() only checks the
>>> group size and is vunerable to a hot plug increasing the group size
>>> after it returns. That check should be replaced by this series's logic
>>> instead.
>>
>> As my my understanding, the essence of this problem is that only the
>> user owner of the iommu_group could attach an UNMANAGED domain to it.
>> If I understand it right, how about introducing a new interface to
>> allocate a user managed domain and storing the user file pointer in it.
>
> For iommu_attach_device() the semantic is simple non-sharing, so there
> is no need for the file * at all, it can just be NULL.
The file * being NULL means the device is only owned by the kernel
driver. Perhaps we can check this pointer in iommu_attach_device() to
avoid using it for user domain attachment.
>
>> Does above help here?
>
> No, iommu_attach_device() is kernel only and should not interact with
> userspace.
The existing iommu_attach_device() allows only for singleton group. As
we have added group ownership attribute, we can enforce this interface
only for kernel domain usage.
>
> I'm also going to see if I can learn what Tegra is doing with
> iommu_attach_group()
Okay! Thank you!
>
> Jason
>
Best regards,
baolu
next prev parent reply other threads:[~2021-11-18 1:17 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-15 2:05 [PATCH 00/11] Fix BUG_ON in vfio_iommu_group_notifier() Lu Baolu
2021-11-15 2:05 ` [PATCH 01/11] iommu: Add device dma ownership set/release interfaces Lu Baolu
2021-11-15 13:14 ` Christoph Hellwig
2021-11-16 1:57 ` Lu Baolu
2021-11-16 13:46 ` Jason Gunthorpe
2021-11-17 5:22 ` Lu Baolu
2021-11-17 13:35 ` Jason Gunthorpe
2021-11-18 1:12 ` Lu Baolu [this message]
2021-11-18 14:10 ` Jason Gunthorpe
2021-11-18 2:39 ` Tian, Kevin
2021-11-18 13:33 ` Jason Gunthorpe
2021-11-19 5:44 ` Tian, Kevin
2021-11-19 11:14 ` Lu Baolu
2021-11-19 15:06 ` Jörg Rödel
2021-11-19 15:43 ` Jason Gunthorpe
2021-11-20 11:16 ` Lu Baolu
2021-11-19 12:56 ` Jason Gunthorpe
2021-11-15 20:38 ` Bjorn Helgaas
2021-11-16 1:52 ` Lu Baolu
2021-11-15 2:05 ` [PATCH 02/11] driver core: Set DMA ownership during driver bind/unbind Lu Baolu
2021-11-15 6:59 ` Greg Kroah-Hartman
2021-11-15 13:20 ` Christoph Hellwig
2021-11-15 13:38 ` Jason Gunthorpe
2021-11-15 13:19 ` Christoph Hellwig
2021-11-15 13:24 ` Jason Gunthorpe
2021-11-15 15:37 ` Robin Murphy
2021-11-15 15:56 ` Jason Gunthorpe
2021-11-15 18:15 ` Christoph Hellwig
2021-11-15 18:35 ` Robin Murphy
2021-11-15 19:39 ` Jason Gunthorpe
2021-11-15 2:05 ` [PATCH 03/11] PCI: pci_stub: Suppress kernel DMA ownership auto-claiming Lu Baolu
2021-11-15 13:21 ` Christoph Hellwig
2021-11-15 13:31 ` Jason Gunthorpe
2021-11-15 15:14 ` Robin Murphy
2021-11-15 16:17 ` Jason Gunthorpe
2021-11-15 17:54 ` Robin Murphy
2021-11-15 18:19 ` Christoph Hellwig
2021-11-15 18:44 ` Robin Murphy
2021-11-15 19:22 ` Jason Gunthorpe
2021-11-15 20:58 ` Robin Murphy
2021-11-15 21:19 ` Jason Gunthorpe
2021-11-15 20:48 ` Bjorn Helgaas
2021-11-15 22:17 ` Bjorn Helgaas
2021-11-16 6:05 ` Lu Baolu
2021-11-15 2:05 ` [PATCH 04/11] PCI: portdrv: " Lu Baolu
2021-11-15 20:44 ` Bjorn Helgaas
2021-11-16 7:24 ` Lu Baolu
2021-11-16 20:22 ` Bjorn Helgaas
2021-11-16 20:48 ` Jason Gunthorpe
2021-11-15 2:05 ` [PATCH 05/11] iommu: Add security context management for assigned devices Lu Baolu
2021-11-15 13:22 ` Christoph Hellwig
2021-11-16 7:25 ` Lu Baolu
2021-11-15 2:05 ` [PATCH 06/11] iommu: Expose group variants of dma ownership interfaces Lu Baolu
2021-11-15 13:27 ` Christoph Hellwig
2021-11-16 9:42 ` Lu Baolu
2021-11-15 2:05 ` [PATCH 07/11] vfio: Use DMA_OWNER_USER to declaim passthrough devices Lu Baolu
2021-11-15 2:05 ` [PATCH 08/11] vfio: Remove use of vfio_group_viable() Lu Baolu
2021-11-15 2:05 ` [PATCH 09/11] vfio: Delete the unbound_list Lu Baolu
2021-11-15 2:05 ` [PATCH 10/11] vfio: Remove iommu group notifier Lu Baolu
2021-11-15 2:05 ` [PATCH 11/11] iommu: Remove iommu group changes notifier Lu Baolu
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