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Bug #12917

bhyve should always use Unrestricted Guest

Added by Patrick Mooney 3 months ago. Updated about 2 months ago.

Status:
Closed
Priority:
Normal
Category:
bhyve
Start date:
Due date:
% Done:

100%

Estimated time:
Difficulty:
Medium
Tags:
bhyve
Gerrit CR:

Description

Since the Westmere microarchitecture, Intel CPUs have had the capability to run with the "Unrestricted Guest", where VMX guests are able to run in real mode (allowing for guest software such as boot roms). FreeBSD bhyve supported older CPUs by loading the OS directly with helpers such as grub2-bhyve, where the guest is started directly in protected mode. Since illumos bhyve has never shipped any of those helpers, and already enforces availability of Unrestricted Guest mode, we should automatically enable it and removed that complication from bhyve.

History

#1

Updated by Electric Monk 3 months ago

  • Gerrit CR set to 767
#2

Updated by Patrick Mooney 3 months ago

It should be noted that FreeBSD bhyve implements this (Unrestricted Guest) as a per-vCPU capabilities which can be toggled. Being able to choose to run it on anything other than all (or no) vCPUs is a bit nonsensical.

#3

Updated by Patrick Mooney 2 months ago

With this change applied, my bootrom-utilizing guests are still able to boot and run without issue. Without Unrestricted Guest enabled, they would be unable to start at all from real mode.

#4

Updated by Electric Monk about 2 months ago

  • Status changed from In Progress to Closed
  • % Done changed from 0 to 100

git commit c3ae3afa3e57b39e29577c4b791adbe511bb7e3f

commit  c3ae3afa3e57b39e29577c4b791adbe511bb7e3f
Author: Patrick Mooney <pmooney@pfmooney.com>
Date:   2020-07-28T19:43:29.000Z

    12916 bhyve should be able to limit vmx capabilities
    12917 bhyve should always use Unrestricted Guest
    Reviewed by: Mike Zeller <mike.zeller@joyent.com>
    Approved by: Dan McDonald <danmcd@joyent.com>

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