kvm disabled-by-bios flag should be displayed in /proc/cpuinfo

[Dustin Kirkland ]

The kvm-ok utility helps users determine if their hardware is capable of running hardware accelerated KVM virtual machines.

The easy part of the check is looking for (vmx|svm) in /proc/cpuinfo.

This is not entirely sufficient, however, as users (or OEMs) can disable VT arbitrarily in BIOS, rendering VT unusable. However, the kernel continues printing (vmx|svm) to /proc/cpuinfo's flags.

The kvm module detects this, though, on module load, and adds a printk to dmesg:

[ 15.147129] kvm: disabled by bios

The dmesg log is not ideal, obviously, as these logs roll eventually.

Furthermore, the story in /proc/cpuinfo is clearly not the full picture.

What is needed, then, is the display of an additional flag in /proc/cpuinfo, noting that svm_disabled|vmx_disabled, when the kernel determines that this is so.

[Sergey Svishchev (svs)]

FWIW, kvm-ok now checks for "disabled by bios" message in dmesg.

[Dustin Kirkland  (kirkland)]

Correct, kvm-ok does grep dmesg.

However, this bug is a wishlist against the kernel, asking the kernel to add this information to /proc/cpuinfo, so that it would be more persistent than writing a log entry to the dmesg buffer.