Merge pull request #566 from speed47/test

built from commit 3e2b6cc734
 dated 2026-04-20 11:02:38 +0000
 by Stéphane Lesimple (speed47_github@speed47.net)

 Prepare release v26.33.0420xxx

FAQ.md

@@ -0,0 +1,145 @@
+# Questions
+
+- [What to expect from this tool?](#what-to-expect-from-this-tool)
+- [Why was this script written in the first place?](#why-was-this-script-written-in-the-first-place)
+- [Why are those vulnerabilities so different than regular CVEs?](#why-are-those-vulnerabilities-so-different-than-regular-cves)
+- [What do "affected", "vulnerable" and "mitigated" mean exactly?](#what-do-affected-vulnerable-and-mitigated-mean-exactly)
+- [What are the main design decisions regarding this script?](#what-are-the-main-design-decisions-regarding-this-script)
+- [Everything is indicated in `sysfs` now, is this script still useful?](#everything-is-indicated-in-sysfs-now-is-this-script-still-useful)
+- [How does this script work?](#how-does-this-script-work)
+- [Which BSD OSes are supported?](#which-bsd-oses-are-supported)
+- [Why is my OS not supported?](#why-is-my-os-not-supported)
+- [The tool says there is an updated microcode for my CPU, but I don't have it!](#the-tool-says-there-is-an-updated-microcode-for-my-cpu-but-i-dont-have-it)
+- [The tool says that I need a more up-to-date microcode, but I have the more recent version!](#the-tool-says-that-i-need-a-more-up-to-date-microcode-but-i-have-the-more-recent-version)
+- [Which rules are governing the support of a CVE in this tool?](#which-rules-are-governing-the-support-of-a-cve-in-this-tool)
+
+# Answers
+
+## What to expect from this tool?
+
+This tool does its best to determine where your system stands on each of the collectively named [transient execution](https://en.wikipedia.org/wiki/Transient_execution_CPU_vulnerability) vulnerabilities (also sometimes called "speculative execution" vulnerabilities) that were made public since early 2018. It doesn't attempt to run any kind of exploit, and can't guarantee that your system is secure, but rather helps you verifying if your system is affected, and if it is, checks whether it has the known mitigations in place to avoid being vulnerable.
+Some mitigations could also exist in your kernel that this script doesn't know (yet) how to detect, or it might falsely detect mitigations that in the end don't work as expected (for example, on backported or modified kernels).
+
+Please also note that for Spectre vulnerabilities, all software can possibly be exploited, this tool only verifies that the kernel (which is the core of the system) you're using has the proper protections in place. Verifying all the other software is out of the scope of this tool. As a general measure, ensure you always have the most up to date stable versions of all the software you use, especially for those who are exposed to the world, such as network daemons and browsers.
+
+This tool has been released in the hope that it'll be useful, but don't use it to jump to definitive conclusions about your security: hardware vulnerabilities are [complex beasts](#why-are-those-vulnerabilities-so-different-than-regular-cves), and collective understanding of each vulnerability is evolving with time.
+
+## Why was this script written in the first place?
+
+The first commit of this script is dated *2018-01-07*, only 4 days after the world first heard about the Meltdown and the Spectre attacks. With those attacks disclosure, a _whole new range of vulnerabilities_ that were previously thought to be mostly theoretical and only possible in very controlled environments (labs) - hence of little interest for most except researchers - suddenly became completely mainstream and apparently trivial to conduct on an immensely large number of systems.
+
+On the few hours and days after that date, the whole industry went crazy. Proper, verified information about these vulnerabilities was incredibly hard to find, because before this, even the CPU vendors never had to deal with managing security vulnerabilities at scale, as software vendors do since decades. There were a lot of FUD, and the apparent silence of the vendors was enough for most to fear the worst. The whole industry had everything to learn about this new type of vulnerabilities. However, most systems administrators had a few simple questions:
+
+- Am **I** vulnerable? And if yes,
+- What do I have to do to mitigate these vulnerabilities on **my** system?
+
+Unfortunately, answering those questions was very difficult (and still is to some extent), even if the safe answer to the first question was "you probably are". This script was written to try to give simple answers to those simple questions, and was made to evolve as the information about these vulnerabilities became available. On the first few days, there was several new versions published **per day**.
+
+## Why are those vulnerabilities so different than regular CVEs?
+
+Those are hardware vulnerabilities, while most of the CVEs we see everyday are software vulnerabilities. A quick comparison would be:
+
+Software vulnerability:
+- Can be fixed? Yes.
+- How to fix? Update the software (or uninstall it!)
+
+Hardware vulnerability:
+- Can be fixed? No, only mitigated (or buy new hardware!)
+- How to ~~fix~~ mitigate? In the worst case scenario, 5 "layers" need to be updated: the microcode/firmware, the host OS kernel, the hypervisor, the VM OS kernel, and possibly all the software running on the machine. Sometimes only a subset of those layers need to be updated. In yet other cases, there can be several possible mitigations for the same vulnerability, implying different layers. Yes, it can get horribly complicated.
+
+A more detailed video explanation is available here: https://youtu.be/2gB9U1EcCss?t=425
+
+## What do "affected", "vulnerable" and "mitigated" mean exactly?
+
+- **Affected** means that your CPU's hardware, as it went out of the factory, is known to be concerned by a specific vulnerability, i.e. the vulnerability applies to your hardware model. Note that it says nothing about whether a given vulnerability can actually be used to exploit your system. However, an unaffected CPU will never be vulnerable, and doesn't need to have mitigations in place.
+- **Vulnerable** implies that you're using an **affected** CPU, and means that a given vulnerability can be exploited on your system, because no (or insufficient) mitigations are in place.
+- **Mitigated** implies that a previously **vulnerable** system has followed all the steps (updated all the required layers) to ensure a given vulnerability cannot be exploited. About what "layers" mean, see [the previous question](#why-are-those-vulnerabilities-so-different-than-regular-cves).
+
+## What are the main design decisions regarding this script?
+
+There are a few rules that govern how this tool is written.
+
+1) It should be okay to run this script in a production environment. This implies, but is not limited to:
+
+   * 1a. Never modify the system it's running on, and if it needs to e.g. load a kernel module it requires, that wasn't loaded before it was launched, it'll take care to unload it on exit
+   * 1b. Never attempt to "fix" or "mitigate" any vulnerability, or modify any configuration. It just reports what it thinks is the status of your system. It leaves all decisions to the sysadmin.
+   * 1c. Never attempt to run any kind of exploit to tell whether a vulnerability is mitigated, because it would violate 1a), could lead to unpredictable system behavior, and might even lead to wrong conclusions, as some PoC must be compiled with specific options and prerequisites, otherwise giving wrong information (especially for Spectre). If you want to run PoCs, do it yourself, but please read carefully about the PoC and the vulnerability. PoCs about a hardware vulnerability are way more complicated and prone to false conclusions than PoCs for software vulnerabilities.
+
+2) Never look at the kernel version to tell whether it supports mitigation for a given vulnerability. This implies never hardcoding version numbers in the script. This would defeat the purpose: this script should be able to detect mitigations in unknown kernels, with possibly backported or forward-ported patches. Also, don't believe what `sysfs` says, when possible. See the next question about this.
+
+3) Never look at the microcode version to tell whether it has the proper mechanisms in place to support mitigation for a given vulnerability. This implies never hardcoding version numbers in the script. Instead, look for said mechanisms, as the kernel would do.
+
+4) When a CPU is not known to be explicitly unaffected by a vulnerability, make the assumption that it is. This strong design choice has it roots in the early speculative execution vulnerability days (see [this answer](#why-was-this-script-written-in-the-first-place)), and is still a good approach as of today.
+
+## Everything is indicated in `sysfs` now, is this script still useful?
+
+A lot as changed since 2018. Nowadays, the industry adapted and this range of vulnerabilities is almost "business as usual", as software vulnerabilities are. However, due to their complexity, it's still not as easy as just checking a version number to ensure a vulnerability is closed.
+
+Granted, we now have a standard way under Linux to check whether our system is affected, vulnerable, mitigated against most of these vulnerabilities. By having a look at the `sysfs` hierarchy, and more precisely the `/sys/devices/system/cpu/vulnerabilities/` folder, one can have a pretty good insight about its system state for each of the listed vulnerabilities. Note that the output can be a little different with some vendors (e.g. Red Hat has some slightly different output than the vanilla kernel for some vulnerabilities), but it's still a gigantic leap forward, given where we were in 2018 when this script was started, and it's very good news. The kernel is the proper place to have this because the kernel knows everything about itself (the mitigations it might have), and the CPU (its model, and microcode features that are exposed). Note however that some vulnerabilities are not reported through this file hierarchy at all, such as Zenbleed.
+
+However I see a few reasons why this script might still be useful to you, and that's why its development has not halted when the `sysfs` hierarchy came out:
+
+- A given version of the kernel doesn't have knowledge about the future. To put it in another way: a given version of the kernel only has the understanding of a vulnerability available at the time it was compiled. Let me explain this: when a new vulnerability comes out, new versions of the microcode and kernels are released, with mitigations in place. With such a kernel, a new `sysfs` entry will appear. However, after a few weeks or months, corner cases can be discovered, previously-thought unaffected CPUs can turn out to be affected in the end, and sometimes mitigations can end up being insufficient.  Of course, if you're always running the latest kernel version from kernel.org, this issue might be limited for you. The spectre-meltdown-checker script doesn't depend on a kernel's knowledge and understanding of a vulnerability to compute its output. That is, unless you tell it to (using the `--sysfs-only` option).
+
+- Mitigating a vulnerability completely can sometimes be tricky, and have a lot of complicated prerequisites, depending on your kernel version, CPU vendor, model and even sometimes stepping, CPU microcode, hypervisor support, etc. The script gives a very detailed insight about each of the prerequisites of mitigation for every vulnerability, step by step, hence pointing out what is missing on your system as a whole to completely mitigate an issue.
+
+- The script can be pointed at a kernel image, and will deep dive into it, telling you if this kernel will mitigate vulnerabilities that might be present on your system. This is a good way to verify before booting a new kernel, that it'll mitigate the vulnerabilities you expect it to, especially if you modified a few config options around these topics.
+
+- The script will also work regardless of the custom patches that might be integrated in the kernel you're running (or you're pointing it to, in offline mode), and completely ignores the advertised kernel version, to tell whether a given kernel mitigates vulnerabilities. This is especially useful for non-vanilla kernel, where patches might be backported, sometimes silently (this has already happened, too).
+
+- Educational purposes: the script gives interesting insights about a vulnerability, and how the different parts of the system work together to mitigate it.
+
+There are probably other reasons, but that are the main ones that come to mind. In the end, of course, only you can tell whether it's useful for your use case ;)
+
+## How does this script work?
+
+On one hand, the script gathers information about your CPU, and the features exposed by its microcode. To do this, it uses the low-level CPUID instruction (through the `cpuid` kernel module under Linux, and the `cpucontrol` tool under BSD), and queries to the MSR registers of your CPU (through the `msr` kernel module under Linux, and the `cpucontrol` tool under BSD).
+
+On another hand, the script looks into the kernel image your system is running on, for clues about the mitigations it supports. Of course, this is very specific for each operating system, even if the implemented mitigation is functionally the same, the actual code is completely specific. As you can imagine, the Linux kernel code has a few in common with a BSD kernel code, for example. Under Linux, the script supports looking into the kernel image, and possibly the System.map and kernel config file, if these are available. Under BSD, it looks into the kernel file only.
+
+Then, for each vulnerability it knows about, the script decides whether your system is [affected, vulnerable, and mitigated](#what-do-affected-vulnerable-and-mitigated-mean-exactly) against it, using the information it gathered about your hardware and your kernel.
+
+## Which BSD OSes are supported?
+
+For the BSD range of operating systems, the script will work as long as the BSD you're using supports `cpuctl` and `linprocfs`. This is not the case for OpenBSD for example. Known BSD flavors having proper support are: FreeBSD, NetBSD, DragonflyBSD. Derivatives of those should also work. To know why other BSDs will likely never be supported, see [why is my OS not supported?](#why-is-my-os-not-supported).
+
+## Why is my OS not supported?
+
+This tool only supports Linux, and [some flavors of BSD](#which-bsd-oses-are-supported). Other OSes will most likely never be supported, due to [how this script works](#how-does-this-script-work). It would require implementing these OSes specific way of querying the CPU. It would also require to get documentation (if available) about how this OS mitigates each vulnerability, down to this OS kernel code, and if documentation is not available, reverse-engineer the difference between a known old version of a kernel, and a kernel that mitigates a new vulnerability. This means that all the effort has to be duplicated times the number of supported OSes, as everything is specific, by construction. It also implies having a deep understanding of every OS, which takes years to develop. However, if/when other tools appear for other OSes, that share the same goal of this one, they might be listed here as a convenience.
+
+## The tool says there is an updated microcode for my CPU, but I don't have it!
+
+Even if your operating system is fully up to date, the tool might still tell you that there is a more recent microcode version for your CPU. Currently, it uses (and merges) information from 4 sources:
+
+- The official [Intel microcode repository](https://github.com/intel/Intel-Linux-Processor-Microcode-Data-Files)
+- The awesome platomav's [MCExtractor database](https://github.com/platomav/MCExtractor) for non-Intel CPUs
+- The official [linux-firmware](https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git) repository for AMD
+- Specific Linux kernel commits that sometimes hardcode microcode versions, such as for [Zenbleed](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=522b1d69219d8f083173819fde04f994aa051a98) or for the bad [Spectre](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kernel/cpu/intel.c#n141) microcodes
+
+Generally, it means a more recent version of the microcode has been seen in the wild. However, fully public availability of this microcode might be limited yet, or your OS vendor might have chosen not to ship this new version (yet), maybe because it's currently being tested, or for other reasons. This tool can't tell you when or if this will be the case. You should ask your vendor about it. Technically, you can still go and upgrade your microcode yourself, and use this tool to confirm whether you did it successfully. Updating the microcode for you is out of the scope of this tool, as this would violate [rule 1b](#what-are-the-main-design-decisions-regarding-this-script).
+
+## The tool says that I need a more up-to-date microcode, but I have the more recent version!
+
+This can happen for a few reasons:
+
+- Your CPU is no longer supported by the vendor. In that case, new versions of the microcode will never be published, and vulnerabilities requiring microcode features will never be fixed. On most of these vulnerabilities, you'll have no way to mitigate the issue on a vulnerable system, appart from buying a more recent CPU. Sometimes, you might be able to mitigate the issue by disabling a CPU feature instead (often at the cost of speed). When this is the case, the script will list this as one of the possible mitigations for the vulnerability.
+
+- The vulnerability is recent, and your CPU has not yet received a microcode update for the vendor. Often, these updates come in batches, and it can take several batches to cover all the supported CPUs.
+
+In both cases, you can contact your vendor to know whether there'll be an update or not, and if yes, when. For Intel, at the time this FAQ entry was written, such guidance was [available here](https://software.intel.com/content/www/us/en/develop/topics/software-security-guidance/processors-affected-consolidated-product-cpu-model.html).
+
+## Which rules are governing the support of a CVE in this tool?
+
+On the early days, it was easy: just Spectre and Meltdown (hence the tool name), because that's all we had. Now that this range of vulnerability is seeing a bunch of newcomers every year, this question is legitimate.
+
+To stick with this tool's goal, a good indication as to why a CVE should be supported, is when mitigating it requires either kernel modifications, microcode modifications, or both.
+
+Counter-examples include (non-exhaustive list):
+
+- [CVE-2019-14615](https://github.com/speed47/spectre-meltdown-checker/issues/340), mitigating this issue is done by updating the Intel driver. This is out of the scope of this tool.
+- [CVE-2019-15902](https://github.com/speed47/spectre-meltdown-checker/issues/304), this CVE is due to a bad backport in the stable kernel. If the faulty backport was part of the mitigation of another supported CVE, and this bad backport was detectable (without hardcoding kernel versions, see [rule 2](#why-are-those-vulnerabilities-so-different-than-regular-cves)), it might have been added as a bullet point in the concerned CVE's section in the tool. However, this wasn't the case.
+- The "[Take A Way](https://github.com/speed47/spectre-meltdown-checker/issues/344)" vulnerability, AMD said that they believe this is not a new attack, hence there were no microcode and no kernel modification made. As there is nothing to look for, this is out of the scope of this tool.
+- [CVE-2020-0550](https://github.com/speed47/spectre-meltdown-checker/issues/347), the vendor thinks this is hardly exploitable in the wild, and as mitigations would be too performance impacting, as a whole the industry decided to not address it. As there is nothing to check for, this is out of the scope of this tool.
+- [CVE-2020-0551](https://github.com/speed47/spectre-meltdown-checker/issues/348), the industry decided to not address it, as it is believed mitigations for other CVEs render this attack practically hard to make, Intel just released an updated SDK for SGX to help mitigate the issue, but this is out of the scope of this tool.
+
+Look for the [information](https://github.com/speed47/spectre-meltdown-checker/issues?q=is%3Aissue+is%3Aopen+label%3Ainformation) tag in the issues list for more examples.

README.md

@@ -272,23 +272,23 @@ In **Hardware-only** mode, the script only reports CPU information and per-CVE h
 
 - Get the latest version of the script using `curl` *or* `wget`
 
-    ```bash
-    curl -L https://meltdown.ovh -o spectre-meltdown-checker.sh
-    wget https://meltdown.ovh -O spectre-meltdown-checker.sh
-    ```
+```bash
+curl -L https://meltdown.ovh -o spectre-meltdown-checker.sh
+wget https://meltdown.ovh -O spectre-meltdown-checker.sh
+```
 
 - Inspect the script. You never blindly run scripts you downloaded from the Internet, do you?
 
-    ```bash
-    vim spectre-meltdown-checker.sh
-    ```
+```bash
+vim spectre-meltdown-checker.sh
+```
 
 - When you're ready, run the script as root
 
-    ```bash
-    chmod +x spectre-meltdown-checker.sh
-    sudo ./spectre-meltdown-checker.sh
-    ```
+```bash
+chmod +x spectre-meltdown-checker.sh
+sudo ./spectre-meltdown-checker.sh
+```
 
 ### Using a docker container
 

doc/UNSUPPORTED_CVE_LIST.md

@@ -307,13 +307,3 @@ A weakness in AMD's microcode signature verification (AES-CMAC hash) allows load
 Exploits a synchronization failure in the AMD stack engine via an undocumented MSR bit, targeting AMD SEV-SNP confidential VMs. Requires hypervisor-level (ring 0) access.
 
 **Why out of scope:** Not a transient/speculative execution side channel. This is an architectural attack on AMD SEV-SNP confidential computing that requires hypervisor access, which is outside the threat model of this tool.
-
-## No CVE — Jump Conditional Code (JCC) Erratum
-
-- **Issue:** [#329](https://github.com/speed47/spectre-meltdown-checker/issues/329)
-- **Intel whitepaper:** [Mitigations for Jump Conditional Code Erratum](https://www.intel.com/content/dam/support/us/en/documents/processors/mitigations-jump-conditional-code-erratum.pdf)
-- **Affected CPUs:** Intel 6th through 10th generation Core and Xeon processors (Skylake through Cascade Lake)
-
-A microarchitectural correctness erratum where a conditional jump instruction that straddles or ends at a 64-byte instruction fetch boundary can corrupt the branch predictor state, potentially causing incorrect execution. Intel addressed this in a November 2019 microcode update. Compilers and assemblers (GCC, LLVM, binutils) also introduced alignment options (`-mbranch-alignment`, `-x86-branches-within-32B-boundaries`) to pad jump instructions away from boundary conditions, preserving performance on CPUs with updated microcode.
-
-**Why out of scope:** The JCC erratum is a microarchitectural correctness bug, not a transient or speculative execution side-channel vulnerability. No CVE was ever assigned. Red Hat noted that privilege escalation "has not been ruled out" but made no definitive security finding, and no exploit has been demonstrated. There is no Linux sysfs entry, no CPUID bit, and no MSR flag exposing the mitigation status. The microcode fix introduces no detectable hardware indicator, so checking for it would require maintaining a per-CPU-stepping minimum microcode version table (the design principle 3 exception) — costly to maintain without a CVE anchor or confirmed exploitability to justify the ongoing work. The kernel compiler mitigation is a build-time-only change (instruction alignment) with no observable runtime state.

spectre-meltdown-checker.sh

@@ -13,7 +13,7 @@
 #
 # Stephane Lesimple
 #
-VERSION='26.33.0420863'
+VERSION='26.33.0420460'
 
 # --- Common paths and basedirs ---
 readonly VULN_SYSFS_BASE="/sys/devices/system/cpu/vulnerabilities"
@@ -1674,76 +1674,58 @@ is_cpu_srbds_free() {
 
 }
 
-# Check whether the CPU is architecturally immune to MMIO Stale Data
-# Mirrors the kernel's arch_cap_mmio_immune() helper: ALL THREE ARCH_CAP bits must be set:
-#   ARCH_CAP_SBDR_SSDP_NO (bit 13), ARCH_CAP_FBSDP_NO (bit 14), ARCH_CAP_PSDP_NO (bit 15)
-# Returns: 0 if immune, 1 otherwise
-is_arch_cap_mmio_immune() {
-    [ "$cap_sbdr_ssdp_no" = 1 ] && [ "$cap_fbsdp_no" = 1 ] && [ "$cap_psdp_no" = 1 ]
-}
-
 # Check whether the CPU is known to be unaffected by MMIO Stale Data (CVE-2022-21123/21125/21166)
-# Matches the kernel's NO_MMIO whitelist plus arch_cap_mmio_immune().
-# Model inventory and kernel-commit history are documented in check_mmio_linux().
 # Returns: 0 if MMIO-free, 1 if affected or unknown
 is_cpu_mmio_free() {
+    # source: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/kernel/cpu/common.c
+    #
+    # CPU affection logic from kernel (51802186158c, v5.19):
+    #   Bug is set when: cpu_matches(blacklist, MMIO) AND NOT arch_cap_mmio_immune()
+    #   arch_cap_mmio_immune() requires ALL THREE bits set:
+    #     ARCH_CAP_FBSDP_NO (bit 14) AND ARCH_CAP_PSDP_NO (bit 15) AND ARCH_CAP_SBDR_SSDP_NO (bit 13)
+    #
+    # Intel Family 6 model blacklist (unchanged since v5.19):
+    #   HASWELL_X (0x3F)
+    #   BROADWELL_D (0x56), BROADWELL_X (0x4F)
+    #   SKYLAKE_X (0x55), SKYLAKE_L (0x4E), SKYLAKE (0x5E)
+    #   KABYLAKE_L (0x8E), KABYLAKE (0x9E)
+    #   ICELAKE_L (0x7E), ICELAKE_D (0x6C), ICELAKE_X (0x6A)
+    #   COMETLAKE (0xA5), COMETLAKE_L (0xA6)
+    #   LAKEFIELD (0x8A)
+    #   ROCKETLAKE (0xA7)
+    #   ATOM_TREMONT (0x96), ATOM_TREMONT_D (0x86), ATOM_TREMONT_L (0x9C)
+    #
+    # Vendor scope: Intel only. Non-Intel CPUs are not affected.
     parse_cpu_details
-    is_arch_cap_mmio_immune && return 0
-    # Non-Intel x86 vendors the kernel unconditionally whitelists (AMD/Hygon all
-    # families; Centaur/Zhaoxin fam 7 only).
-    if is_amd || is_hygon; then
+    # ARCH_CAP immunity: all three bits must be set
+    if [ "$cap_sbdr_ssdp_no" = 1 ] && [ "$cap_fbsdp_no" = 1 ] && [ "$cap_psdp_no" = 1 ]; then
         return 0
     fi
-    if { [ "$cpu_vendor" = "CentaurHauls" ] || [ "$cpu_vendor" = "Shanghai" ]; } && [ "$cpu_family" = 7 ]; then
-        return 0
-    fi
-    # Intel NO_MMIO whitelist
-    if is_intel && [ "$cpu_family" = 6 ]; then
-        if [ "$cpu_model" = "$INTEL_FAM6_TIGERLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_TIGERLAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ALDERLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ALDERLAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_GOLDMONT" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_GOLDMONT_D" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_GOLDMONT_PLUS" ]; then
-            return 0
+    if is_intel; then
+        if [ "$cpu_family" = 6 ]; then
+            if [ "$cpu_model" = "$INTEL_FAM6_HASWELL_X" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_BROADWELL_D" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_BROADWELL_X" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE_X" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE_L" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_KABYLAKE_L" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_KABYLAKE" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_L" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_D" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_X" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_COMETLAKE" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_COMETLAKE_L" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_LAKEFIELD" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ROCKETLAKE" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT_D" ] ||
+                [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT_L" ]; then
+                return 1
+            fi
         fi
     fi
-    return 1
-}
 
-# Check whether the CPU's MMIO Stale Data status is unknown ("out of servicing period")
-# Matches the kernel's X86_BUG_MMIO_UNKNOWN: Intel CPU not MMIO-free and not in the
-# MMIO blacklist. The kernel reports "Unknown: No mitigations" for such CPUs.
-# Callers: check_mmio_linux, check_mmio_bsd
-# Returns: 0 if unknown, 1 if known (either affected or not affected)
-is_cpu_mmio_unknown() {
-    parse_cpu_details
-    # Only Intel can reach the unknown bucket — other x86 vendors are whitelisted by vendor-id.
-    is_intel || return 1
-    is_cpu_mmio_free && return 1
-    if [ "$cpu_family" = 6 ]; then
-        if [ "$cpu_model" = "$INTEL_FAM6_HASWELL_X" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_BROADWELL_D" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_BROADWELL_X" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE_X" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_SKYLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_KABYLAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_KABYLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_D" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ICELAKE_X" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_COMETLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_COMETLAKE_L" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_LAKEFIELD" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ROCKETLAKE" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT_D" ] ||
-            [ "$cpu_model" = "$INTEL_FAM6_ATOM_TREMONT_L" ]; then
-            return 1
-        fi
-    fi
     return 0
 }
 
@@ -5558,7 +5540,7 @@ check_cpu() {
         pr_info_nol "  * CPU explicitly indicates not being affected by MMIO Stale Data (FBSDP_NO & PSDP_NO & SBDR_SSDP_NO): "
         if [ "$cap_sbdr_ssdp_no" = -1 ]; then
             pstatus yellow UNKNOWN "couldn't read MSR"
-        elif is_arch_cap_mmio_immune; then
+        elif [ "$cap_sbdr_ssdp_no" = 1 ] && [ "$cap_fbsdp_no" = 1 ] && [ "$cap_psdp_no" = 1 ]; then
             pstatus green YES
         else
             pstatus yellow NO
@@ -6248,30 +6230,16 @@ check_mds_linux() {
 # vim: set ts=4 sw=4 sts=4 et:
 # MMIO Stale Data (Processor MMIO Stale Data Vulnerabilities) - BSD mitigation check
 check_mmio_bsd() {
-    # No BSD (FreeBSD, OpenBSD, NetBSD, DragonFlyBSD) has implemented an OS-level
-    # MMIO Stale Data mitigation. All four stopped at MDS/TAA. Microcode update is
-    # the only partial defense available, and without OS-level VERW invocation it
-    # cannot close the vulnerability.
-    local unk
-    unk="your CPU's MMIO Stale Data status is unknown (Intel never officially assessed this CPU, its servicing period has ended)"
     if ! is_cpu_affected "$cve"; then
         pvulnstatus "$cve" OK "your CPU vendor reported your CPU model as not affected"
-    elif is_cpu_mmio_unknown; then
-        if [ "$opt_paranoid" = 1 ]; then
-            pvulnstatus "$cve" VULN "$unk, and no BSD mitigation exists"
-            explain "There is no known mitigation for this CPU model. Even with up-to-date microcode, BSD kernels do not invoke VERW for MMIO Stale Data clearing. Only a hardware replacement can fully address this."
-        else
-            pvulnstatus "$cve" UNK "$unk; no BSD mitigation exists in any case"
-        fi
     else
-        pvulnstatus "$cve" VULN "your CPU is affected and no BSD has implemented an MMIO Stale Data mitigation"
-        explain "No BSD kernel currently implements an MMIO Stale Data mitigation (which would require invoking VERW at context switches and VM-entries). Updating CPU microcode alone does not mitigate this vulnerability without OS cooperation."
+        pvulnstatus "$cve" UNK "your CPU is affected, but mitigation detection has not yet been implemented for BSD in this script"
     fi
 }
 
 # MMIO Stale Data (Processor MMIO Stale Data Vulnerabilities) - Linux mitigation check
 check_mmio_linux() {
-    local status sys_interface_available msg kernel_mmio kernel_mmio_can_tell mmio_mitigated mmio_smt_mitigated mystatus mymsg unk
+    local status sys_interface_available msg kernel_mmio kernel_mmio_can_tell mmio_mitigated mmio_smt_mitigated mystatus mymsg
     status=UNK
     sys_interface_available=0
     msg=''
@@ -6373,33 +6341,9 @@ check_mmio_linux() {
         #
         # No models have been added to or removed from the MMIO blacklist since v5.19.
         #
-        # 7df548840c49 (v6.0, NO_MMIO whitelist added, Pawan Gupta 2022-08-03):
-        #   Intel Family 6:
-        #     TIGERLAKE (0x8D), TIGERLAKE_L (0x8C)
-        #     ALDERLAKE (0x97), ALDERLAKE_L (0x9A)
-        #     ATOM_GOLDMONT (0x5C), ATOM_GOLDMONT_D (0x5F), ATOM_GOLDMONT_PLUS (0x7A)
-        #   AMD: fam 0x0f-0x12 + X86_FAMILY_ANY (all families)
-        #   Hygon: all families
-        #   Centaur fam 7, Zhaoxin fam 7
-        #
-        # Kernel logic (v6.0+):
-        #   if (!arch_cap_mmio_immune(ia32_cap)) {
-        #       if (cpu_matches(cpu_vuln_blacklist, MMIO))
-        #           setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
-        #       else if (!cpu_matches(cpu_vuln_whitelist, NO_MMIO))
-        #           setup_force_cpu_bug(X86_BUG_MMIO_UNKNOWN);
-        #   }
-        #   => Intel CPUs that are neither blacklisted nor whitelisted (e.g. Ivy Bridge,
-        #      Haswell client, Broadwell client, Sandy Bridge, pre-Goldmont Atom, etc.) get
-        #      X86_BUG_MMIO_UNKNOWN and report "Unknown: No mitigations" in sysfs. Intel
-        #      never published an affected-processor evaluation for these models because
-        #      their servicing period had already ended.
-        #   => is_cpu_mmio_unknown() matches this set so the script can report UNK (or
-        #      VULN under --paranoid) rather than the misleading "not affected" that
-        #      a plain blacklist check would produce.
-        #
         # immunity: ARCH_CAP_SBDR_SSDP_NO (bit 13) AND ARCH_CAP_FBSDP_NO (bit 14) AND ARCH_CAP_PSDP_NO (bit 15)
         #   All three must be set. Checked via arch_cap_mmio_immune() in common.c.
+        #   Bug is set only when: cpu_matches(blacklist, MMIO) AND NOT arch_cap_mmio_immune().
         #
         # microcode mitigation: ARCH_CAP_FB_CLEAR (bit 17) -- VERW clears fill buffers.
         #   Alternative: MD_CLEAR CPUID + FLUSH_L1D CPUID when MDS_NO is not set (legacy path).
@@ -6478,17 +6422,6 @@ check_mmio_linux() {
     if ! is_cpu_affected "$cve"; then
         # override status & msg in case CPU is not vulnerable after all
         pvulnstatus "$cve" OK "your CPU vendor reported your CPU model as not affected"
-    elif [ "$opt_sysfs_only" != 1 ] && is_cpu_mmio_unknown; then
-        # Bypass the normal sysfs reconciliation: sysfs reports "Unknown: No mitigations"
-        # only on v6.0-v6.15. On earlier and on v6.16+ kernels it wrongly says "Not affected"
-        # for these CPUs (which predate FB_CLEAR microcode and Intel's affected-processor list).
-        unk="your CPU's MMIO Stale Data status is unknown (Intel never officially assessed this CPU, its servicing period has ended)"
-        if [ "$opt_paranoid" = 1 ]; then
-            pvulnstatus "$cve" VULN "$unk, and no mitigation is available"
-            explain "There is no known mitigation for this CPU model. Intel ended its servicing period without evaluating whether it is affected by MMIO Stale Data vulnerabilities, so no FB_CLEAR-capable microcode was released. Consider replacing affected hardware."
-        else
-            pvulnstatus "$cve" UNK "$unk; no mitigation is available in any case"
-        fi
     else
         if [ "$opt_sysfs_only" != 1 ]; then
             # compute mystatus and mymsg from our own logic