bhyve: do not show the fwcfg device in the guest's user interface
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Authored by wanpengqian_gmail.com on Fri, Oct 2, 5:56 AM.

Details

Reviewers

corvink
bnovkov
markj

Group Reviewers

bhyve

Summary

Windows has no driver for the fwcfg device (QEMU0002) and lists it in
Device Manager as an unknown device. Give it _STA 0x0B (present,
enabled, functioning, not shown in the user interface), which is what
QEMU does.

Signed-off-by: Wanpeng Qian <wanpengqian@gmail.com>
Sponsored by: keelos.dev

Test Plan

main (f958aa7e7), FreeBSD guest started with -o lpc.fwcfg=qemu, acpidump -d in the guest:

before

Device (FWCF)
{
    Name (_HID, "QEMU0002")  // _HID: Hardware ID
    Name (_STA, 0x0F)  // _STA: Status

after

Name (_STA, 0x0B)  // _STA: Status

With the same change on FreeBSD 14.5: a Windows guest with a TPM (which needs lpc.fwcfg=qemu) listed "Unknown device" (ACPI\QEMU0002) in Device Manager before and does not after. Linux's qemu_fw_cfg driver still attaches to the device (/sys/firmware/qemu_fw_cfg), as it does on QEMU.

The TPM device, the other user of acpi_device, keeps _STA 0x0F.

Diff Detail

Repository

rG FreeBSD src repository

Lint

Lint Skipped

Unit

Tests Skipped

Build Status

Buildable 78237
Build 75120: arc lint + arc unit

Event Timeline

wanpengqian_gmail.com created this revision.Fri, Oct 2, 5:56 AM

wanpengqian_gmail.com held this revision as a draft.

Herald added a reviewer: bhyve. · View Herald TranscriptFri, Oct 2, 5:56 AM

Herald added subscribers: bcran, rgrimes, imp. · View Herald Transcript

Harbormaster completed remote builds in B77600: Diff 188365.Fri, Oct 2, 5:56 AM

wanpengqian_gmail.com added a parent revision: D60223: bhyve: keep the reserved bits of EFLAGS on a task switch.Fri, Oct 2, 5:56 AM

wanpengqian_gmail.com added a child revision: D60225: bhyve: e82545: drop frames that are too long for the guest.

wanpengqian_gmail.com edited the test plan for this revision. (Show Details)

wanpengqian_gmail.com added a reviewer: corvink.Fri, Oct 2, 6:30 AM

wanpengqian_gmail.com published this revision for review.Fri, Oct 2, 7:01 AM

bnovkov accepted this revision.Fri, Oct 2, 12:29 PM

This revision is now accepted and ready to land.Fri, Oct 2, 12:29 PM

markj accepted this revision.Wed, Oct 14, 7:02 PM

markj added a subscriber: markj.

markj added inline comments.

usr.sbin/bhyve/acpi_device.c
199–203	It'd be nice to define symbolic constants for these bits.

Build _STA from ACPICA's ACPI_STA_DEVICE_* constants (markj)

This revision now requires review to proceed.Thu, Oct 15, 5:14 AM

Harbormaster completed remote builds in B78237: Diff 189954.Thu, Oct 15, 5:14 AM

Thanks, done: _STA is now built from ACPICA's ACPI_STA_DEVICE_PRESENT/ENABLED/FUNCTIONING/UI bits (acpi_device.h already includes acpi.h).

wanpengqian_gmail.com marked an inline comment as done.Thu, Oct 15, 5:20 AM

markj accepted this revision as: markj.Thu, Oct 15, 6:28 PM

This revision is now accepted and ready to land.Thu, Oct 15, 6:28 PM

Just a side note: There's a driver for Windows [1]. However, it's not very useful because it drives the VMCoreInfo device which isn't implemented in bhyve [2]. Honestly, I don't even know if it refuses to load due to the missing fwcfg device. There's also a dummy driver which should load [3].

[1] https://github.com/virtio-win/kvm-guest-drivers-windows/blob/d92b9c073ec1108f51846d0bd109c5796b46fd36/fwcfg64/fwcfg.inf
[2] https://www.qemu.org/docs/master/specs/vmcoreinfo.html
[3] https://github.com/virtio-win/kvm-guest-drivers-windows/blob/d92b9c073ec1108f51846d0bd109c5796b46fd36/fwcfg/qemufwcfg.inf

Thanks for the pointers. _STA 0x0B only clears the "show in UI" bit, so the device is still enumerated: anyone who wants qemufwcfg.inf (or fwcfg64, if bhyve ever grows VMCoreInfo) can still install it, and it shows up under "Show hidden devices". It just no longer appears as an unknown device by default, which is what QEMU does too.