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Differential D42233

amd64: Add sysctl knobs for loader tunables
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Authored by zlei on Oct 16 2023, 5:22 PM.
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Subscribers
bcran
imp
patmaddox
rgrimes

Details

Reviewers
kib
alc
grehan
Group Reviewers
bhyve
Summary

The following loader tunable do not have corresponding sysctl MIB
entries. Add them so that they can be retrieved, and sysctl -T will
also report them correctly.

  1. hw.clflush_disable
  2. hw.memtest.tests
  3. hw.skz63_enable
  4. hw.use_xsave
  5. hw.vmm.ept.use_exec_only
  6. hw.vmm.ept.use_hw_ad_bits
  7. hw.vmm.ept.use_superpages
  8. hw.vmm.npt.enable_superpage
  9. hw.xsave_mask

MFC after: 1 week

Diff Detail

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rG FreeBSD src repository
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Event Timeline

zlei created this revision.Oct 16 2023, 5:22 PM
Herald added a reviewer: bhyve. · View Herald TranscriptOct 16 2023, 5:22 PM
Herald added subscribers: bcran, rgrimes, imp. · View Herald Transcript
zlei requested review of this revision.Oct 16 2023, 5:22 PM
zlei added a parent revision: D42251: vmx: Prefer consistent naming for loader tunables.Oct 17 2023, 9:50 AM
alc added inline comments.Oct 17 2023, 5:09 PM
sys/amd64/vmm/amd/npt.c
51
62

I would suggest initializing the variables at their definitions, rather than at run-time.

kib added inline comments.Oct 17 2023, 5:44 PM
sys/amd64/amd64/fpu.c
173

The description is wrong.

That said, I do not see much use for these and other x86-related tunables to be exposed as sysctl. They are debugging tools, useful only for people who understand the code.

zlei added inline comments.Oct 18 2023, 3:24 AM
sys/amd64/amd64/fpu.c
173

Thanks for the explanation.
That make sense. Those tunables are not documented and confused me until git blame shows theirs history.

zlei mentioned this in D42218: x86: Add sysctl knobs for loader tunables.Oct 18 2023, 3:28 AM
zlei added a child revision: D42274: pmap: Prefer consistent naming for loader tunable.Oct 18 2023, 10:32 AM
kib added inline comments.Oct 18 2023, 4:40 PM
sys/amd64/amd64/fpu.c
173

If you want to add some information about these tunables, a source comment would be appropriate.

patmaddox added a subscriber: patmaddox.Oct 19 2023, 9:43 PM
zlei abandoned this revision.Oct 20 2023, 9:28 AM

Abandoned as no need to add sysctl knobs for debugging purpose only tunables.

They are debugging tools, useful only for people who understand the code.

sys/amd64/vmm/amd/npt.c
66

Actually the flag enable_superpage can be retrieved from npt_flags which is exposed via sysctl MIB hw.vmm.npt.pmap_flags.

So hw.vmm.npt.enable_superpage should be for debugging purpose only. A new sysctl knob for it is redundant.

sys/amd64/vmm/intel/ept.c
76

Redundant.
They can be retrieved from sysctl MIB hw.vmm.ept.pmap_flags.

Revision Contents
Changeset List

PathSize
sys/
amd64/
amd64/
5 lines
3 lines
9 lines
6 lines
vmm/
amd/
6 lines
intel/
13 lines

Diff 128846

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sys/amd64/amd64/fpu.c

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sys/amd64/amd64/initcpu.c

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sys/amd64/amd64/machdep.c

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sys/amd64/amd64/pmap.c

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sys/amd64/vmm/amd/npt.c

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sys/amd64/vmm/intel/ept.c

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