[libvirt] [PATCH v2] qemu: Introduce caching whether /dev/kvm is accessible

[Daniel P. Berrangé]

On Thu, Nov 01, 2018 at 09:07:05AM +0100, Michal Privoznik wrote:
> On 11/01/2018 05:11 AM, Ján Tomko wrote:
> > IIRC the problem was that users with vmx disabled in BIOS setup needed
> > to delete libvirt's qemuCaps cache manually after enabling it even after
> > restarting the system.
> 
> Sounds like it. The commit that introduced the check is d87df9bd39b.
> 
> Honestly, I don't think we need to care about perms - we can assume
> those are set properly (as they don't change often). What we have to

We can't assume permissions are correct. One of the core issues we hit
was that the udev rule which sets the permissions has been in the QEMU
RPM historically. So you can have the kernel module loaded automatically
by systemd when it detects VMX, but its permissions will be 0600 until
the qemu-kvm RPM is installed and udev is triggered to fix the permissions
to 0666.

> care about is inserting/removing kvm module (even though it's not
> necessary these days since virtualbox has learned how to co-exist with
> KVM).

Regards,
Daniel
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