KVM 安装中IOMMU 警告问题解决

Posted 2020-11-10

IOMMU 警告问题解决

Typically by default, IOMMU is not enabled in Linux. I’ll show how to enable that virtualization feature on Fedora Linux!

1. First, check if IOMMU support is enabled by running this command:

sudo virt-host-validate

If in the output you see something similar to the following, continue on below for help.
...
QEMU: Checking if IOMMU is enabled by kernel : FAIL
(IOMMU appears to be disabled in kernel. Add intel_iommu=on to kernel cmdline arguments)
...

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2. Edit the file /etc/default/grub and add intel_iommu=on to the existing GRUB_CMDLINE_LINUX line.

Note: I have a lot going on here for mine, such as a fix for a weird usb power issue of my motherboard, enabling nested virtualization for kvm and more. Disregard those things and only add intel_iommu=on for this task!
GRUB_TIMEOUT=5
GRUB_DISTRIBUTOR="$(sed ‘s, release .*$,,g‘ /etc/system-release)"
GRUB_DEFAULT=saved
GRUB_DISABLE_SUBMENU=true
GRUB_TERMINAL_OUTPUT="console"
GRUB_CMDLINE_LINUX="nouveau.modeset=0 rd.driver.blacklist=nouveau nomodeset rhgb quiet xhci-hcd.quirks=262144 kvm-intel.nested=1 intel_iommu=on"
GRUB_DISABLE_RECOVERY="true"

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3. Next, update grub2 via:

sudo grub2-mkconfig -o /boot/grub2/grub.cfg

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4. And finally reboot.

sudo reboot

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Now IOMMU should come back as PASS in this check: Run virt-host-validate again.