Hello,
with kernel v6.16-rc5-121-gbc9ff192a6c9 I see this:
cat /sys/devices/system/cpu/vulnerabilities/tsa
Mitigation: Clear CPU buffers
dmesg | grep micro
[ 1.479203] microcode: Current revision: 0x0a20102e
[ 1.479206] microcode: Updated early from: 0x0a201016
So, this works.
but same machine with 6.6.97:
dmesg | grep micro
[ 0.451496] Transient Scheduler Attacks: Vulnerable: Clear CPU buffers
attempted, no microcode
[ 1.077149] microcode: Current revision: 0x0a20102e
[ 1.077152] microcode: Updated early from: 0x0a201016
so:
cat /sys/devices/system/cpu/vulnerabilities/tsa
Vulnerable: Clear CPU buffers attempted, no microcode
but it is switched on:
zcat /proc/config.gz | grep TSA
CONFIG_MITIGATION_TSA=y
And other stuff which need microcode works:
cat /sys/devices/system/cpu/vulnerabilities/spec_rstack_overflow
Mitigation: Safe RET
without microcode you wwould see:
Vulnerable: Safe RET, no microcode
6.12.37 broken too
6.15.6 works
v6.16-rc5-121-gbc9ff192a6c9 works
This is a:
processor : 11
vendor_id : AuthenticAMD
cpu family : 25
model : 33
model name : AMD Ryzen 5 5600X 6-Core Processor
stepping : 0
microcode : 0xa20102e
Is something missing in 6.6.y and 6.12.y?
Thomas
(already submitted @ Fedora; advised to post here to upstream as well)
-------- Forwarded Message --------
Subject: regression in 6.15.5: KVM guest launch FAILSs with missing CPU feature error (sbpb, ibpb-brtype)
Date: Sun, 13 Jul 2025 17:37:57 -0400
From: pgnd <pgnd(a)dev-mail.net>
Reply-To: pgnd(a)dev-mail.net
To: kernel(a)lists.fedoraproject.org
i'm seeing a regression on Fedora 42 kernel 6.15.4 -> 6.15.5 on AMD Ryzen 5 5600G host (x86_64)
kvm guests that launch ok under kernels 6.15.[3,4] fail with the following error when attempting to autostart under 6.15.5:
internal error: Failed to autostart VM: operation failed: guest CPU doesn't match specification: missing features: sbpb,ibpb-brtype
no changes made to libvirt, qemu, or VM defs between kernel versions.
re-booting to old kernel versions restores expected behavior.
maybe related (?) to recent changes in AMD CPU feature exposure / mitigation handling in kernel 6.15.5?
i've opened a bug:
https://bugzilla.redhat.com/show_bug.cgi?id=2379784
I'm announcing the release of the 6.12.38 kernel.
Only users of AMD x86-based processors need to upgrade, all others may
skip this release.
The updated 6.12.y git tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.12.y
and can be browsed at the normal kernel.org git web browser:
https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary
thanks,
greg k-h
------------
Makefile | 2 +-
arch/x86/kernel/cpu/amd.c | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
Borislav Petkov (AMD) (1):
x86/CPU/AMD: Properly check the TSA microcode
Greg Kroah-Hartman (1):
Linux 6.12.38
I'm announcing the release of the 6.6.98 kernel.
Only users of AMD x86-based processors need to upgrade, all others may
skip this release.
The updated 6.6.y git tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.6.y
and can be browsed at the normal kernel.org git web browser:
https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary
thanks,
greg k-h
------------
Makefile | 2 +-
arch/x86/kernel/cpu/amd.c | 1 +
2 files changed, 2 insertions(+), 1 deletion(-)
Borislav Petkov (AMD) (1):
x86/CPU/AMD: Properly check the TSA microcode
Greg Kroah-Hartman (1):
Linux 6.6.98
I'm announcing the release of the 6.1.145 kernel.
Only users of AMD x86-based processors need to upgrade, all others may
skip this release.
The updated 6.1.y git tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-6.1.y
and can be browsed at the normal kernel.org git web browser:
https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary
thanks,
greg k-h
------------
Makefile | 2 +-
arch/x86/kernel/cpu/amd.c | 5 +++--
2 files changed, 4 insertions(+), 3 deletions(-)
Borislav Petkov (AMD) (1):
x86/CPU/AMD: Properly check the TSA microcode
Greg Kroah-Hartman (1):
Linux 6.1.145
I'm announcing the release of the 5.15.188 kernel.
Only users of AMD x86-based processors need to upgrade, all others may
skip this release.
The updated 5.15.y git tree can be found at:
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git linux-5.15.y
and can be browsed at the normal kernel.org git web browser:
https://git.kernel.org/?p=linux/kernel/git/stable/linux-stable.git;a=summary
thanks,
greg k-h
------------
Makefile | 2 +-
arch/x86/kernel/cpu/amd.c | 5 +++--
2 files changed, 4 insertions(+), 3 deletions(-)
Borislav Petkov (AMD) (1):
x86/CPU/AMD: Properly check the TSA microcode
Greg Kroah-Hartman (1):
Linux 5.15.188