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

Bug #535373 reported by Dustin Kirkland 
This bug affects 3 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

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.

Changed in linux (Ubuntu):
importance: Undecided → Wishlist
status: New → Triaged
Changed in cpu-checker:
importance: Undecided → Medium
status: New → Triaged
tags: added: kernel-series-unknown
Revision history for this message
Sergey Svishchev (svs) wrote :

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

Revision history for this message
Dustin Kirkland  (kirkland) wrote :

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.

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