[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[Thomas Huth]

Please provide information how you started QEMU, and some information
about your PCI device (e.g. the output of lspci).

** Information type changed from Private Security to Public

** Changed in: qemu
       Status: New => Incomplete

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Incomplete

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

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[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[IndrasenaReddy Gali]

qemu-system-x86_64 -name guest=fedora24 -machine q35,accel=kvm,kernel-irqchip=split \
        -enable-kvm \
        -m 4G \
        -smp 8,sockets=1,cores=8,threads=1 \
        -device intel-iommu,intremap=on,caching-mode=on,aw-bits=48  \
        -drive file=<OS_IMAGE_FILE>,format=raw \
        -device ioh3420,id=pcie.1,chassis=1 \
        -device virtio-net-pci,bus=pcie.1,disable-legacy=on,disable-modern=off,iommu_platform=on,ats=on,netdev=net0 \
        -netdev user,id=net0,hostfwd=tcp::1111-:22\
        -device vfio-pci,host=3f:02.1  \
		-device vfio-pci,host=3f:02.2  \
		-device vfio-pci,host=3f:02.3 \
		-device vfio-pci,host=3f:02.4 \
        -device vfio-pci,host=3d:02.4 \
		-device vfio-pci,host=3d:02.5 \
		-device vfio-pci,host=3d:02.6 \
        -nographic

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Incomplete

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

To manage notifications about this bug go to:
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[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[IndrasenaReddy Gali]

Please find the above qemu command to lunch guest machine

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Incomplete

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1851664/+subscriptions

[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[Alex Williamson]

Presumably w-bits (aw-bits?) implies using intel-iommu, there's a
opportunity for the vfio iommu backend to return -ENOSPC (-28) if we
exceed the default number of in-flight DMA mappings per container.  The
default limit is 65535.  You can try increasing this by changing the
dma_entry_limit module option on the vfio_iommu_type1 module.  Note that
in a typical vIOMMU config there's a container per device, so the number
of VFs attached is possibly not a factor.  It is however a lot of DMA
mappings for a single device if this is the issue and you'd generally
want to boot the guest with iommu=pt in order to have reasonable
assigned device performance with a vIOMMU, which would also greatly
reduce the number of mappings.

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Incomplete

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1851664/+subscriptions

[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[IndrasenaReddy Gali]

After increasing dma_entry_limit limit no issue observed.

But ideal senario device is getting hung and recovery happening only
with host hard rebooting.

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Incomplete

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1851664/+subscriptions

[Bug 1851664] Re: qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's to guest machine

[Launchpad Bug Tracker]

[Expired for QEMU because there has been no activity for 60 days.]

** Changed in: qemu
       Status: Incomplete => Expired

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Title:
  qemu-system-x86_64: "VFIO_MAP_DMA : -28" error when we attache 6 VF's
  to guest machine

Status in QEMU:
  Expired

Bug description:
  We are trying to attach 6 VF's to the guest machine on 4.1.1 qemu emulator.
  We are observing "VFIO_MAP_DMA : -28" error.

  We are using w-bits=48 bits while lunching VM.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1851664/+subscriptions