From: Matthew Rosato <mjrosato@linux.ibm.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: kvm@vger.kernel.org, Kevin Tian <kevin.tian@intel.com>,
dri-devel@lists.freedesktop.org,
Vineeth Vijayan <vneethv@linux.ibm.com>,
Diana Craciun <diana.craciun@oss.nxp.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Longfang Liu <liulongfang@huawei.com>,
linux-s390@vger.kernel.org, "Liu, Yi L" <yi.l.liu@intel.com>,
Will Deacon <will@kernel.org>, Joerg Roedel <joro@8bytes.org>,
Halil Pasic <pasic@linux.ibm.com>,
iommu@lists.linux.dev, Nicolin Chen <nicolinc@nvidia.com>,
Christian Borntraeger <borntraeger@linux.ibm.com>,
intel-gfx@lists.freedesktop.org, Zhi Wang <zhi.a.wang@intel.com>,
Jason Herne <jjherne@linux.ibm.com>,
Eric Farman <farman@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Eric Auger <eric.auger@redhat.com>,
Alex Williamson <alex.williamson@redhat.com>,
Harald Freudenberger <freude@linux.ibm.com>,
Rodrigo Vivi <rodrigo.vivi@intel.com>,
intel-gvt-dev@lists.freedesktop.org,
Tony Krowiak <akrowiak@linux.ibm.com>,
Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
Yishai Hadas <yishaih@nvidia.com>,
Cornelia Huck <cohuck@redhat.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>,
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>,
Sven Schnelle <svens@linux.ibm.com>,
Robin Murphy <robin.murphy@arm.com>,
Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: [PATCH v2 00/11] Connect VFIO to IOMMUFD
Date: Mon, 14 Nov 2022 09:55:21 -0500 [thread overview]
Message-ID: <2890d53a-2437-c74c-2082-1ee29414878f@linux.ibm.com> (raw)
In-Reply-To: <Y3JPZwEHjGDU4Oyq@nvidia.com>
On 11/14/22 9:23 AM, Jason Gunthorpe wrote:
> On Thu, Nov 10, 2022 at 10:01:13PM -0500, Matthew Rosato wrote:
>> On 11/7/22 7:52 PM, Jason Gunthorpe wrote:
>>> This series provides an alternative container layer for VFIO implemented
>>> using iommufd. This is optional, if CONFIG_IOMMUFD is not set then it will
>>> not be compiled in.
>>>
>>> At this point iommufd can be injected by passing in a iommfd FD to
>>> VFIO_GROUP_SET_CONTAINER which will use the VFIO compat layer in iommufd
>>> to obtain the compat IOAS and then connect up all the VFIO drivers as
>>> appropriate.
>>>
>>> This is temporary stopping point, a following series will provide a way to
>>> directly open a VFIO device FD and directly connect it to IOMMUFD using
>>> native ioctls that can expose the IOMMUFD features like hwpt, future
>>> vPASID and dynamic attachment.
>>>
>>> This series, in compat mode, has passed all the qemu tests we have
>>> available, including the test suites for the Intel GVT mdev. Aside from
>>> the temporary limitation with P2P memory this is belived to be fully
>>> compatible with VFIO.
>>
>> AFAICT there is no equivalent means to specify
>> vfio_iommu_type1.dma_entry_limit when using iommufd; looks like
>> we'll just always get the default 65535.
>
> No, there is no arbitary limit on iommufd
Yeah, that's what I suspected. But FWIW, userspace checks the advertised limit via VFIO_IOMMU_GET_INFO / VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL, and this is still being advertised as 65535 when using iommufd. I don't think there is a defined way to return 'ignore this value'.
This should go away later when we bind to iommufd directly since QEMU would not be sharing the type1 codepath in userspace.
>
>> Was this because you envision the limit being not applicable for
>> iommufd (limits will be enforced via either means and eventually we
>> won't want to ) or was it an oversight?
>
> The limit here is primarily about limiting userspace abuse of the
> interface.
>
> iommufd is using GFP_KERNEL_ACCOUNT which shifts the responsiblity to
> cgroups, which is similar to how KVM works.
>
> So, for a VM sandbox you'd set a cgroup limit and if a hostile
> userspace in the sanbox decides to try to OOM the system it will hit
> that limit, regardless of which kernel APIs it tries to abuse.
>
> This work is not entirely complete as we also need the iommu driver to
> use GFP_KERNEL_ACCOUNT for allocations connected to the iommu_domain,
> particularly for allocations of the IO page tables themselves - which
> can be quite big.
>
> Jason
next prev parent reply other threads:[~2022-11-14 14:55 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-08 0:52 [PATCH v2 00/11] Connect VFIO to IOMMUFD Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 01/11] vfio: Move vfio_device driver open/close code to a function Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 02/11] vfio: Move vfio_device_assign_container() into vfio_device_first_open() Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 03/11] vfio: Rename vfio_device_assign/unassign_container() Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 04/11] vfio: Move storage of allow_unsafe_interrupts to vfio_main.c Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 05/11] vfio: Use IOMMU_CAP_ENFORCE_CACHE_COHERENCY for vfio_file_enforced_coherent() Jason Gunthorpe
2022-11-10 2:48 ` Tian, Kevin
2022-11-08 0:52 ` [PATCH v2 06/11] vfio-iommufd: Allow iommufd to be used in place of a container fd Jason Gunthorpe
2022-11-10 2:51 ` Tian, Kevin
2022-11-08 0:52 ` [PATCH v2 07/11] vfio-iommufd: Support iommufd for physical VFIO devices Jason Gunthorpe
2022-11-08 6:10 ` Nicolin Chen
2022-11-08 7:41 ` Yi Liu
2022-11-08 17:51 ` Jason Gunthorpe
2022-11-10 3:12 ` Tian, Kevin
2022-11-08 17:48 ` Jason Gunthorpe
2022-11-10 3:11 ` Tian, Kevin
2022-11-10 17:20 ` Jason Gunthorpe
2022-11-10 23:58 ` Tian, Kevin
2022-11-11 4:12 ` Yi Liu
2022-11-14 14:47 ` Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 08/11] vfio-iommufd: Support iommufd for emulated " Jason Gunthorpe
2022-11-10 5:33 ` Tian, Kevin
2022-11-08 0:52 ` [PATCH v2 09/11] vfio: Move container related MODULE_ALIAS statements into container.c Jason Gunthorpe
2022-11-10 5:34 ` Tian, Kevin
2022-11-11 4:13 ` Yi Liu
2022-11-08 0:52 ` [PATCH v2 10/11] vfio: Make vfio_container optionally compiled Jason Gunthorpe
2022-11-08 22:28 ` Alex Williamson
2022-11-09 0:54 ` Jason Gunthorpe
2022-11-09 17:18 ` Alex Williamson
2022-11-09 19:52 ` Jason Gunthorpe
2022-11-10 6:57 ` Tian, Kevin
2022-11-10 17:10 ` Alex Williamson
2022-11-10 17:52 ` Jason Gunthorpe
2022-11-08 0:52 ` [PATCH v2 11/11] iommufd: Allow iommufd to supply /dev/vfio/vfio Jason Gunthorpe
2022-11-10 7:01 ` Tian, Kevin
2022-11-11 4:16 ` Yi Liu
2022-11-11 6:38 ` Yi Liu
2022-11-14 14:50 ` Jason Gunthorpe
2022-11-08 9:19 ` [PATCH v2 00/11] Connect VFIO to IOMMUFD Nicolin Chen
2022-11-08 15:18 ` Yi Liu
2022-11-09 16:57 ` Jason Gunthorpe
2022-11-14 12:51 ` Yi Liu
2022-11-14 14:37 ` Yang, Lixiao
2022-11-15 5:41 ` He, Yu
2022-11-14 14:38 ` Jason Gunthorpe
2022-11-14 14:42 ` Yi Liu
2022-11-15 1:16 ` Matthew Rosato
2022-11-09 9:03 ` Tian, Kevin
2022-11-09 12:48 ` Jason Gunthorpe
2022-11-10 2:16 ` Tian, Kevin
2022-11-11 3:01 ` Matthew Rosato
2022-11-14 14:23 ` Jason Gunthorpe
2022-11-14 14:55 ` Matthew Rosato [this message]
2022-11-14 14:59 ` Jason Gunthorpe
2022-11-14 15:21 ` Matthew Rosato
2022-11-14 19:27 ` Jason Gunthorpe
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