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Bug #13387

closed

bhyve should expose lfence serialize in DE_CFG MSR

Added by Patrick Mooney 9 months ago. Updated 8 months ago.

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

100%

Estimated time:
Difficulty:
Medium
Tags:
Gerrit CR:

Description

The DE_CFG MSR on modern AMD CPUs controls, among other things, whether the lfence instruction is serializing. While we cannot allow the guest to control the setting, we can at least expose whether it has been set (or not) in the host. Doing so will allow guests to safely use lfence; rdtsc for performing a TSC reading when rdtscp is not available.


Related issues

Related to illumos gate - Bug #12998: OpenBSD needs DE_CFG MSR on AMD bhyveClosedPatrick Mooney

Actions
Related to illumos gate - Bug #13383: generalize check for serializing LFENCEClosedPatrick Mooney

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