virt_mshv: fix VMBus by installing unknown SynIC connection intercept#3273
Merged
jstarks merged 1 commit intomicrosoft:mainfrom Apr 14, 2026
Merged
virt_mshv: fix VMBus by installing unknown SynIC connection intercept#3273jstarks merged 1 commit intomicrosoft:mainfrom
jstarks merged 1 commit intomicrosoft:mainfrom
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VMBus channel establishment was broken because the hypervisor silently dropped guest HvPostMessage and HvSignalEvent hypercalls targeting connections it did not recognise. This change registers an HvInterceptTypeUnknownSynicConnection intercept so those hypercalls are forwarded to the VMM, allowing VMBus to function correctly.
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Pull request overview
Fixes VMBus channel establishment on the Linux MSHV backend by ensuring guest HvPostMessage / HvSignalEvent hypercalls targeting unknown SynIC connection IDs are intercepted and forwarded to the VMM, instead of being silently dropped by the hypervisor.
Changes:
- Install an
HvInterceptTypeUnknownSynicConnectionintercept during VM creation onvirt_mshv. - Add inline commentary explaining why the intercept is required for guest-initiated SynIC connections.
smalis-msft
approved these changes
Apr 14, 2026
gurasinghMS
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Apr 17, 2026
…microsoft#3273) VMBus channel establishment was broken because the hypervisor silently dropped guest HvPostMessage and HvSignalEvent hypercalls targeting connections it did not recognise. This change registers an HvInterceptTypeUnknownSynicConnection intercept so those hypercalls are forwarded to the VMM, allowing VMBus to function correctly.
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VMBus channel establishment was broken because the hypervisor silently dropped guest HvPostMessage and HvSignalEvent hypercalls targeting connections it did not recognise. This change registers an HvInterceptTypeUnknownSynicConnection intercept so those hypercalls are forwarded to the VMM, allowing VMBus to function correctly.