A qemu update has been released for Debian GNU/Linux 10 (Buster) to passthrough the pschange-mc-no CPU flag.

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Debian Security Advisory DSA-4566-1 security@debian.org
https://www.debian.org/security/ Salvatore Bonaccorso
November 12, 2019 https://www.debian.org/security/faq
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Package : qemu
Debian Bug : 944623

This update for QEMU, a fast processor emulator, backports support to
passthrough the pschange-mc-no CPU flag. The virtualised MSR seen by a
guest is set to show the bug as fixed, allowing to disable iTLB Multihit
mitigations in nested hypervisors (cf. DSA 4564-1).

For the stable distribution (buster), this problem has been fixed in
version 1:3.1+dfsg-8+deb10u3.

We recommend that you upgrade your qemu packages.

For the detailed security status of qemu please refer to its security
tracker page at:
https://security-tracker.debian.org/tracker/qemu

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://www.debian.org/security/