Re: TSA mitigation doesn't work on 6.6.y

On Fri, 11 Jul 2025, Borislav Petkov wrote:

On Fri, Jul 11, 2025 at 06:56:18PM +0200, Thomas Voegtle wrote:

...

And then I tried 5.15.187, patch applies, but doesn't work.

Pff, try this:

---

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c index d409ba7fba85..8b9753d4822d 100644 --- a/arch/x86/kernel/cpu/amd.c +++ b/arch/x86/kernel/cpu/amd.c @@ -590,6 +590,7 @@ static bool amd_check_tsa_microcode(void)

p.ext_fam = c->x86 - 0xf; p.model = c->x86_model;

• p.ext_model = c->x86_model >> 4; p.stepping = c->x86_stepping;

  if (c->x86 == 0x19) {

@@ -611,12 +612,15 @@ static bool amd_check_tsa_microcode(void) case 0xa70c0: min_rev = 0x0a70c008; break; case 0xaa002: min_rev = 0x0aa00216; break; default:

• 	pr_debug("%s: ucode_rev: 0x%x, current revision: 0x%x\n",
  

• 	pr_info("%s: ucode_rev: 0x%x, current revision: 0x%x\n",
  	 __func__, p.ucode_rev, c->microcode);
  return false;
  

  } }

• pr_info("c->microcode: 0x%x, min_rev: 0x%x, ucode_rev: 0x%x\n",

• c->microcode, min_rev, p.ucode_rev);
  

• if (!min_rev) return false;

@@ -704,6 +708,8 @@ static void bsp_init_amd(struct cpuinfo_x86 *c) }

resctrl_cpu_detect(c);

• tsa_init(c);

}

static void early_detect_mem_encrypt(struct cpuinfo_x86 *c) @@ -743,8 +749,6 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 *c) goto clear_sev;

• tsa_init(c);
• return;

clear_all:

works. cat /sys/devices/system/cpu/vulnerabilities/tsa Mitigation: Clear CPU buffers

dmesg attached

thanks,

Thomas