Hyper-V: Detect Extended Destination ID support
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Authored by cperciva on Feb 22 2026, 4:11 AM.

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Summary

Hyper-V advertises support for the Extended Destination ID standard via
bit 2 of the value returned in the EAX register when the hypervisor
stack properties are queried via CPUID.

This is based on a a commit to the Linux kernel, as there does not seem
to be any other documentation of this feature.

MFC after: 2 weeks

Diff Detail

Repository

rG FreeBSD src repository

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Build Status

Buildable 71443
Build 68326: arc lint + arc unit

Event Timeline

cperciva created this revision.Feb 22 2026, 4:11 AM

Herald added a subscriber: imp. · View Herald TranscriptFeb 22 2026, 4:11 AM

cperciva requested review of this revision.Feb 22 2026, 4:11 AM

Harbormaster completed remote builds in B70871: Diff 172431.Feb 22 2026, 4:11 AM

cperciva added a parent revision: D55431: Bhyve: Detect Extended Destination ID support.Feb 22 2026, 4:11 AM

cperciva added a reviewer: schakrabarti_microsoft.com.Feb 22 2026, 4:16 AM

lwhsu added a reviewer: whu.Mon, Feb 23, 9:45 AM

Only enable if ext_dest_id is set to -1.

Harbormaster completed remote builds in B70929: Diff 172541.Mon, Feb 23, 7:53 PM

schakrabarti_microsoft.com accepted this revision.Mon, Mar 9, 7:19 AM

This revision is now accepted and ready to land.Mon, Mar 9, 7:19 AM

Move detection code into local_apic.c

This revision now requires review to proceed.Tue, Mar 17, 4:00 AM

Harbormaster completed remote builds in B71443: Diff 173784.Tue, Mar 17, 4:00 AM

@schakrabarti_microsoft.com I moved the detection code into local_apic.c since I'm using it for both MSIs and APIC RTEs now, but I assume since it's the same code your previous review applies equally well here.

schakrabarti_microsoft.com accepted this revision.Mon, Mar 23, 6:50 AM

This revision is now accepted and ready to land.Mon, Mar 23, 6:50 AM