From: Alex Williamson <alex.williamson@redhat.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
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Subject: Re: [PATCH v2 10/11] vfio: Make vfio_container optionally compiled
Date: Thu, 10 Nov 2022 10:10:23 -0700 [thread overview]
Message-ID: <20221110101023.28e7a790.alex.williamson@redhat.com> (raw)
In-Reply-To: <BN9PR11MB5276494548F01A42694E366A8C019@BN9PR11MB5276.namprd11.prod.outlook.com>
On Thu, 10 Nov 2022 06:57:57 +0000
"Tian, Kevin" <kevin.tian@intel.com> wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Thursday, November 10, 2022 3:53 AM
> >
> > On Wed, Nov 09, 2022 at 10:18:09AM -0700, Alex Williamson wrote:
> >
> > > DPDK supports no-iommu mode.
> >
> > Er? Huh? How? I thought no-iommu was for applications that didn't do
> > DMA? How is DPDK getting packets in/out without DMA? I guess it snoops
> > in /proc/ or something to learn PFNs of mlock'd memory? <shudder>
>
> iirc dpdk started with UIO plus various tricks (root privilege, hugepage, etc.)
> to lock and learn PFN's from pagemap. Then when migrating it to vfio the
> no-iommu option was introduced to provide UIO compatibility.
IIRC, we essentially introduced no-iommu mode vfio because DPDK started
pushing for extending interrupt support in uio-pci-generic. The UIO
driver is also only meant for devices that don't do DMA, but obviously
DPDK didn't care about that. Rather than extend UIO, we offered this
no-iommu mode in vfio since we already had more extensive MSI support,
were better able to impose restrictions on access to the device, and
using the same device access makes the transition to proper IOMMU
backed configurations more seamless. Thanks,
Alex
next prev parent reply other threads:[~2022-11-10 17:11 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 [this message]
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
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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