TSA mitigation doesn't work on 6.6.y

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