[libvirt] [PATCH v3] qemu: Add check for whether KVM nesting is enabled

Michal Privoznik mprivozn at redhat.com
Thu Dec 13 13:29:05 UTC 2018


On 11/29/18 2:55 AM, John Ferlan wrote:
> Support for nested KVM is handled via a kernel module configuration
> parameters values for kvm_intel, kvm_amd, kvm_hv (PPC), or kvm (s390).
> While it's possible to fetch the kmod config values via virKModConfig,
> unfortunately that is the static value and we need to get the
> current/dynamic value from the kernel file system.
> 
> So this patch adds a new API virHostKVMSupportsNesting that will
> search the 3 kernel modules to get the nesting value and check if
> it is 'Y' (or 'y' just in case) or '1' to return a true/false whether
> the KVM kernel supports nesting.
> 
> We need to do this in order to handle cases where adjustments to
> the value are made after libvirtd is started to force a refetch of
> the latest QEMU capabilities since the correct CPU settings need
> to be made for a guest to add the "vmx=on" to/for the guest config.

Ah, so if nested KVM is not enabled that qemu might report vmx:false and
if it is enabled it reports vmx:true?

ACK in that case.

Michal




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