jcs.org
qemu with hax to log dma reads & writes
jcs.org/2018/11/12/vfio
docs: Add section for NVMe VFIO driver
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20180116060901.17413-9-famz@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
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docs/qemu-block-drivers.texi
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docs/qemu-block-drivers.texi
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With sufficiently new versions of libssh2 and OpenSSH, @code{fsync} is
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supported.
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@node disk_images_nvme
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@subsection NVMe disk images
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NVM Express (NVMe) storage controllers can be accessed directly by a userspace
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driver in QEMU. This bypasses the host kernel file system and block layers
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while retaining QEMU block layer functionalities, such as block jobs, I/O
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throttling, image formats, etc. Disk I/O performance is typically higher than
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with @code{-drive file=/dev/sda} using either thread pool or linux-aio.
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The controller will be exclusively used by the QEMU process once started. To be
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able to share storage between multiple VMs and other applications on the host,
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please use the file based protocols.
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Before starting QEMU, bind the host NVMe controller to the host vfio-pci
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driver. For example:
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@example
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# modprobe vfio-pci
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# lspci -n -s 0000:06:0d.0
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06:0d.0 0401: 1102:0002 (rev 08)
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# echo 0000:06:0d.0 > /sys/bus/pci/devices/0000:06:0d.0/driver/unbind
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# echo 1102 0002 > /sys/bus/pci/drivers/vfio-pci/new_id
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# qemu-system-x86_64 -drive file=nvme://@var{host}:@var{bus}:@var{slot}.@var{func}/@var{namespace}
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@end example
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Alternative syntax using properties:
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@example
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qemu-system-x86_64 -drive file.driver=nvme,file.device=@var{host}:@var{bus}:@var{slot}.@var{func},file.namespace=@var{namespace}
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@end example
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@var{host}:@var{bus}:@var{slot}.@var{func} is the NVMe controller's PCI device
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address on the host.
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@var{namespace} is the NVMe namespace number, starting from 1.
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@node disk_image_locking
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@subsection Disk image file locking
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qemu-doc.texi
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qemu-doc.texi