[PATCH 6.19 068/781] x86/cpu/amd: Correct the microcode table for Zenbleed

Greg Kroah-Hartman
2026-02-25T01:28:45Z

From: Andrew Cooper <andrew.cooper3@citrix.com>

[ Upstream commit fb7bfa31b8e8569f154f2fe0ea6c2f03c0f087aa ]

The good revisions are tied to exact steppings, meaning it's not valid to
match on model number alone, let alone a range.

This is probably only a latent issue. From public microcode archives, the
following CPUs exist 17-30-00, 17-60-00, 17-70-00 and would be captured by the
model ranges. They're likely pre-production steppings, and likely didn't get
Zenbleed microcode, but it's still incorrect to compare them to a different
steppings revision.

Either way, convert the logic to use x86_match_min_microcode_rev(), which is
the preferred mechanism.

Fixes: 522b1d69219d ("x86/cpu/amd: Add a Zenbleed fix")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: x86@kernel.org
Link: https://patch.msgid.link/20251126130352.880424-1-andrew.cooper3@citrix.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/x86/kernel/cpu/amd.c | 30 +++++++++---------------------
1 file changed, 9 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index bc94ff1e250ad..86059f2c0fcd4 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -951,26 +951,14 @@ static void init_amd_zen1(struct cpuinfo_x86 *c)
}
}

-static bool cpu_has_zenbleed_microcode(void)
-{
- u32 good_rev = 0;
-
- switch (boot_cpu_data.x86_model) {
- case 0x30 ... 0x3f: good_rev = 0x0830107b; break;
- case 0x60 ... 0x67: good_rev = 0x0860010c; break;
- case 0x68 ... 0x6f: good_rev = 0x08608107; break;
- case 0x70 ... 0x7f: good_rev = 0x08701033; break;
- case 0xa0 ... 0xaf: good_rev = 0x08a00009; break;
-
- default:
- return false;
- }
-
- if (boot_cpu_data.microcode < good_rev)
- return false;
-
- return true;
-}
+static const struct x86_cpu_id amd_zenbleed_microcode[] = {
+ ZEN_MODEL_STEP_UCODE(0x17, 0x31, 0x0, 0x0830107b),
+ ZEN_MODEL_STEP_UCODE(0x17, 0x60, 0x1, 0x0860010c),
+ ZEN_MODEL_STEP_UCODE(0x17, 0x68, 0x1, 0x08608107),
+ ZEN_MODEL_STEP_UCODE(0x17, 0x71, 0x0, 0x08701033),
+ ZEN_MODEL_STEP_UCODE(0x17, 0xa0, 0x0, 0x08a00009),
+ {}
+};

static void zen2_zenbleed_check(struct cpuinfo_x86 *c)
{
@@ -980,7 +968,7 @@ static void zen2_zenbleed_check(struct cpuinfo_x86 *c)
if (!cpu_has(c, X86_FEATURE_AVX))
return;

- if (!cpu_has_zenbleed_microcode()) {
+ if (!x86_match_min_microcode_rev(amd_zenbleed_microcode)) {
pr_notice_once("Zenbleed: please update your microcode for the most optimal fix\n");
msr_set_bit(MSR_AMD64_DE_CFG, MSR_AMD64_DE_CFG_ZEN2_FP_BACKUP_FIX_BIT);
} else {
--
2.51.0