Difference between revisions of "Virtualization"
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↑ https://gitlab.com/libvirt/libvirt/-/issues/227#note_705948269
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| − | + | ===Running 64KiB guests on 4KiB hosts=== | |
| − | + | When trying to start a VM on a host running with [[Page size|4KiB pages]], you might see the following error message: | |
| − | ===Running | ||
| − | When trying to start a VM on a host running with | ||
<nowiki>qemu-system-ppc64: Can't support 64 kiB guest pages with 4 kiB host pages with this KVM implementation</nowiki> | <nowiki>qemu-system-ppc64: Can't support 64 kiB guest pages with 4 kiB host pages with this KVM implementation</nowiki> | ||
| − | There is an easy workaround for this. If running QEMU directly, add the argument <code>-machine pseries,cap-hpt-max-page-size=4096</code>. If running QEMU via libvirt, add the following section to the guest's libvirt XML (via <code>virsh edit [guest name]</code> or the XML tab in virt-manager): | + | There is an easy workaround for this. If running QEMU directly, add the argument <code>-machine pseries,cap-hpt-max-page-size=4096</code>. If running QEMU via libvirt, add the following section<ref>https://gitlab.com/libvirt/libvirt/-/issues/227#note_705948269</ref> to the guest's libvirt XML (via <code>virsh edit [guest name]</code> or the XML tab in virt-manager): |
<nowiki> | <nowiki> | ||
<features> | <features> | ||
| Line 12: | Line 10: | ||
<maxpagesize unit='KiB'>4</maxpagesize> | <maxpagesize unit='KiB'>4</maxpagesize> | ||
</hpt> | </hpt> | ||
| + | </features></nowiki> | ||
| + | |||
| + | ===Nested KVM=== | ||
| + | |||
| + | In order to be able to run nested KVM, two things must be satisfied: | ||
| + | |||
| + | # The <code>kvm_hv</code> kernel module must be loaded with the <code>nested=1</code> module argument | ||
| + | # The L1 guest must be started with <code>-machine pseries,cap-nested-hv=on</code> as argument to qemu. If running qemu via libvirt, add the following XML fragment to the XML: | ||
| + | <nowiki> | ||
| + | <features> | ||
| + | <nested-hv state="on"/> | ||
</features></nowiki> | </features></nowiki> | ||
Revision as of 22:07, 17 May 2023
Running 64KiB guests on 4KiB hosts
When trying to start a VM on a host running with 4KiB pages, you might see the following error message:
qemu-system-ppc64: Can't support 64 kiB guest pages with 4 kiB host pages with this KVM implementation
There is an easy workaround for this. If running QEMU directly, add the argument -machine pseries,cap-hpt-max-page-size=4096. If running QEMU via libvirt, add the following section[1] to the guest's libvirt XML (via virsh edit [guest name] or the XML tab in virt-manager):
<features>
<hpt>
<maxpagesize unit='KiB'>4</maxpagesize>
</hpt>
</features>
Nested KVM
In order to be able to run nested KVM, two things must be satisfied:
- The
kvm_hvkernel module must be loaded with thenested=1module argument - The L1 guest must be started with
-machine pseries,cap-nested-hv=onas argument to qemu. If running qemu via libvirt, add the following XML fragment to the XML:
<features>
<nested-hv state="on"/>
</features>
