From: Alex Williamson <alex.williamson@redhat.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: "Liu, Yi L" <yi.l.liu@intel.com>,
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Subject: Re: [PATCH v4 2/9] vfio-iommufd: Create iommufd_access for noiommu devices
Date: Wed, 3 May 2023 16:49:16 -0600 [thread overview]
Message-ID: <20230503164916.652d7779.alex.williamson@redhat.com> (raw)
In-Reply-To: <ZFK5AJxhMBGKqWaH@nvidia.com>
On Wed, 3 May 2023 16:41:52 -0300
Jason Gunthorpe <jgg@nvidia.com> wrote:
> > > My general idea to complete the no-iommu feature is to add a new IOCTL
> > > to VFIO that is 'pin iova and return dma addr' that no-iommu userspace
> > > would call instead of trying to abuse mlock and /proc/ to do it. That
> > > ioctl would use the IOAS attached to the access just like a mdev would
> > > do, so it has a real IOVA, but it is not a mdev.
> >
> > This new ioctl may be IOMMUFD ioctl since its input is the IOAS and
> > addr, nothing related to the device. Is it?
>
> No, definately a VFIO special ioctl for VFIO no-iommu mode.
This seems like brushing off the dirty work to vfio. Userspace drivers
relying on no-iommu are in pretty questionable territory already, do we
care if they don't have a good means to pin pages and derive the DMA
address of those pinned pages? As I noted earlier, I'm really not
interested in expanding no-iommu, it's less important now than when it
was added (we have vIOMMUs in VMs now and more platforms with IOMMUs)
and we shouldn't be encouraging its use by further developing the
interface. Thanks,
Alex
next prev parent reply other threads:[~2023-05-03 22:50 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-26 14:54 [PATCH v4 0/9] Enhance vfio PCI hot reset for vfio cdev device Yi Liu
2023-04-26 14:54 ` [PATCH v4 1/9] vfio: Determine noiommu in vfio_device registration Yi Liu
2023-04-27 6:36 ` Tian, Kevin
2023-04-27 7:05 ` Liu, Yi L
2023-04-27 18:35 ` Alex Williamson
2023-04-26 14:54 ` [PATCH v4 2/9] vfio-iommufd: Create iommufd_access for noiommu devices Yi Liu
2023-04-27 6:39 ` Tian, Kevin
2023-04-27 6:59 ` Liu, Yi L
2023-04-27 18:32 ` Alex Williamson
2023-04-28 6:21 ` Yi Liu
2023-04-28 7:00 ` Tian, Kevin
2023-04-28 7:04 ` Yi Liu
2023-04-28 12:07 ` Jason Gunthorpe
2023-04-28 16:07 ` Yi Liu
2023-05-02 18:12 ` Jason Gunthorpe
2023-05-03 9:48 ` Liu, Yi L
2023-05-03 19:42 ` Jason Gunthorpe
2023-05-08 15:46 ` Liu, Yi L
2023-04-28 16:13 ` Yi Liu
2023-05-02 18:22 ` Jason Gunthorpe
2023-05-03 9:57 ` Liu, Yi L
2023-05-03 19:41 ` Jason Gunthorpe
2023-05-03 22:49 ` Alex Williamson [this message]
2023-04-26 14:54 ` [PATCH v4 3/9] vfio/pci: Update comment around group_fd get in vfio_pci_ioctl_pci_hot_reset() Yi Liu
2023-04-26 14:54 ` [PATCH v4 4/9] vfio/pci: Move the existing hot reset logic to be a helper Yi Liu
2023-04-27 6:39 ` Tian, Kevin
2023-04-26 14:54 ` [PATCH v4 5/9] vfio: Mark cdev usage in vfio_device Yi Liu
2023-04-27 6:40 ` Tian, Kevin
2023-04-27 18:43 ` Alex Williamson
2023-04-28 6:42 ` Yi Liu
2023-04-26 14:54 ` [PATCH v4 6/9] iommufd: Reserved -1 in the iommufd xarray Yi Liu
2023-04-27 6:41 ` Tian, Kevin
2023-04-27 7:09 ` Liu, Yi L
2023-04-27 11:55 ` Jason Gunthorpe
2023-04-26 14:54 ` [PATCH v4 7/9] vfio-iommufd: Add helper to retrieve iommufd_ctx and devid for vfio_device Yi Liu
2023-04-27 6:45 ` Tian, Kevin
2023-04-27 7:15 ` Liu, Yi L
2023-04-26 14:54 ` [PATCH v4 8/9] vfio/pci: Extend VFIO_DEVICE_GET_PCI_HOT_RESET_INFO for vfio device cdev Yi Liu
2023-04-27 6:51 ` Tian, Kevin
2023-04-27 20:04 ` Alex Williamson
2023-04-27 20:15 ` Alex Williamson
2023-05-08 15:32 ` Liu, Yi L
2023-05-08 20:29 ` Alex Williamson
2023-04-26 14:54 ` [PATCH v4 9/9] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET Yi Liu
2023-04-27 6:54 ` Tian, Kevin
2023-04-27 7:02 ` Liu, Yi L
2023-04-27 21:55 ` Alex Williamson
2023-05-02 12:55 ` Liu, Yi L
2023-04-26 15:07 ` [PATCH v4 0/9] Enhance vfio PCI hot reset for vfio cdev device Liu, Yi L
2023-04-28 9:28 ` Jiang, Yanting
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