Hi,

On 2026-01-19 17:01, Fiona Ebner wrote:
NOTE: Needs to still be tested on an actually affected system!

I tested both patches with the kernel 6.17.9 on my affected system (Ryzen 9 
9900X, Gigabyte X870 AORUS ELITE WIFI7, Firmware-Version: F8).


Without the patches I get this error with kernel 6.17.9 when using CPU type 
'EPYC':

kvm: warning: host doesn't support requested feature: 
CPUID[eax=07h,ecx=00h].EBX.rdseed [bit 18]
kvm: Host doesn't support requested features
TASK ERROR: start failed: QEMU exited with code 1


With the patches applied I get the same error with more context:

kvm: warning: host doesn't support requested feature: 
CPUID[eax=07h,ecx=00h].EBX.rdseed [bit 18]
WARN: On Zen 5 systems, the rdseed CPU flag might not be available when the CPU 
firmware is outdated. See:
https://security-tracker.debian.org/tracker/CVE-2025-62626
https://pve.proxmox.com/pve-docs/chapter-sysadmin.html#sysadmin_firmware_cpu
kvm: Host doesn't support requested features
TASK ERROR: start failed: QEMU exited with code 1


Tested-by: Markus Frank <[email protected]>


With the 6.17.9 kernel, the rdseed feature bit is not available for
some Zen 5 host CPUs anymore unless the firmware is new enough. QEMU
will complain about the missing feature bit upon VM start. Add some
context to the QEMU error message if the host is Zen 5 (or 6, same CPU
family number, but the warning message already states 'Zen 5'
explicitly and probably the feature bit won't be missing in the first
place).

pve-common:

Fiona Ebner (1):
   procfs tools: cpuinfo: also return CPU vendor and family

  src/PVE/ProcFSTools.pm | 6 ++++++
  1 file changed, 6 insertions(+)


qemu-server:

Fiona Ebner (1):
   vm start: catch outdated Zen 5 firmware

  src/PVE/QemuServer.pm | 13 +++++++++++++
  1 file changed, 13 insertions(+)


Summary over all repositories:
   2 files changed, 19 insertions(+), 0 deletions(-)




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