Public bug reported:
Virtual machines running under qemu using KVM acceleration run with
`-cpu host` can't use the xsaves feature of the processor. An example
guest dmesg log is attached, see errors about "unchecked MSR access
error". Using a `-cpu` model that doesn't advertise xsaves such as
`EPYC` fixes the problem on the guest. The host cpu does support xsaves
and Ubuntu doesn't seem to have any issues with it.
The guest dmesg provided is running linux mainline 5.15, but the issue
happens with every kernel version I've tried, including centos on
4.18.0.
The host cpu is a Ryzen 5 3600
nested guests have trouble running in a guest with `-cpu host` or even
`-cpu EPYC`. They tend to run, but freeze before they finish booting at
random times. Not sure if it's related. Nested guests do seem to be able
to run with `-cpu kvm64`. There are no dmesg errors when a nested guest
freezes.
The Ubuntu host version:
Description:Ubuntu 20.04.3 LTS
Release:20.04
# apt-cache policy qemu-system-x86
qemu-system-x86:
Installed: 1:4.2-3ubuntu6.18
Candidate: 1:4.2-3ubuntu6.18
Version table:
*** 1:4.2-3ubuntu6.18 500
500 http://us.archive.ubuntu.com/ubuntu focal-updates/main amd64
Packages
100 /var/lib/dpkg/status
1:4.2-3ubuntu6.17 500
500 http://us.archive.ubuntu.com/ubuntu focal-security/main amd64
Packages
1:4.2-3ubuntu6 500
500 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages
ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: qemu (not installed)
ProcVersionSignature: Ubuntu 5.4.0-89.100-generic 5.4.143
Uname: Linux 5.4.0-89-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: pass
Date: Fri Nov 12 00:19:10 2021
InstallationDate: Installed on 2021-10-20 (22 days ago)
InstallationMedia: Ubuntu-Server 20.04.3 LTS "Focal Fossa" - Release amd64
(20210824)
MachineType: System manufacturer System Product Name
ProcEnviron:
SHELL=/bin/bash
LANG=en_US.UTF-8
TERM=screen-256color
XDG_RUNTIME_DIR=
PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-89-generic
root=UUID=15509878-abfa-45b1-b8c2-c99db1ececf7 ro
SourcePackage: qemu
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 06/15/2021
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 4002
dmi.board.asset.tag: Default string
dmi.board.name: PRIME X570-P
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: Default string
dmi.chassis.version: Default string
dmi.modalias:
dmi:bvnAmericanMegatrendsInc.:bvr4002:bd06/15/2021:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnPRIMEX570-P:rvrRevX.0x:cvnDefaultstring:ct3:cvrDefaultstring:
dmi.product.family: To be filled by O.E.M.
dmi.product.name: System Product Name
dmi.product.sku: SKU
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
** Affects: qemu (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug focal uec-images
** Attachment added: "guest dmesg"
https://bugs.launchpad.net/bugs/1950706/+attachment/5540209/+files/debian-guest-dmesg.txt
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https://bugs.launchpad.net/bugs/1950706
Title:
VMs running under qemu+kvm can't use xsaves processor feature
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