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-rw-r--r--Documentation/admin-guide/hw-vuln/mds.rst34
1 files changed, 13 insertions, 21 deletions
diff --git a/Documentation/admin-guide/hw-vuln/mds.rst b/Documentation/admin-guide/hw-vuln/mds.rst
index 48ca0bd856..48c7b0b72a 100644
--- a/Documentation/admin-guide/hw-vuln/mds.rst
+++ b/Documentation/admin-guide/hw-vuln/mds.rst
@@ -102,9 +102,19 @@ The possible values in this file are:
* - 'Vulnerable'
- The processor is vulnerable, but no mitigation enabled
* - 'Vulnerable: Clear CPU buffers attempted, no microcode'
- - The processor is vulnerable but microcode is not updated.
-
- The mitigation is enabled on a best effort basis. See :ref:`vmwerv`
+ - The processor is vulnerable but microcode is not updated. The
+ mitigation is enabled on a best effort basis.
+
+ If the processor is vulnerable but the availability of the microcode
+ based mitigation mechanism is not advertised via CPUID, the kernel
+ selects a best effort mitigation mode. This mode invokes the mitigation
+ instructions without a guarantee that they clear the CPU buffers.
+
+ This is done to address virtualization scenarios where the host has the
+ microcode update applied, but the hypervisor is not yet updated to
+ expose the CPUID to the guest. If the host has updated microcode the
+ protection takes effect; otherwise a few CPU cycles are wasted
+ pointlessly.
* - 'Mitigation: Clear CPU buffers'
- The processor is vulnerable and the CPU buffer clearing mitigation is
enabled.
@@ -119,24 +129,6 @@ to the above information:
'SMT Host state unknown' Kernel runs in a VM, Host SMT state unknown
======================== ============================================
-.. _vmwerv:
-
-Best effort mitigation mode
-^^^^^^^^^^^^^^^^^^^^^^^^^^^
-
- If the processor is vulnerable, but the availability of the microcode based
- mitigation mechanism is not advertised via CPUID the kernel selects a best
- effort mitigation mode. This mode invokes the mitigation instructions
- without a guarantee that they clear the CPU buffers.
-
- This is done to address virtualization scenarios where the host has the
- microcode update applied, but the hypervisor is not yet updated to expose
- the CPUID to the guest. If the host has updated microcode the protection
- takes effect otherwise a few cpu cycles are wasted pointlessly.
-
- The state in the mds sysfs file reflects this situation accordingly.
-
-
Mitigation mechanism
-------------------------