diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2019-02-18 23:13:06 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-05-14 19:19:40 +0200 |
| commit | 96ef7afd8c38c88419d1bd85f6cc25c3aa403224 (patch) | |
| tree | 9dc12c2daec5001da5e1cd378eb9099d44575b52 /Documentation/index.rst | |
| parent | eb2aa332cfe39e05585534017ad94b7717dbdf85 (diff) | |
x86/speculation/mds: Add mds_clear_cpu_buffers()
commit 6a9e529272517755904b7afa639f6db59ddb793e upstream.
The Microarchitectural Data Sampling (MDS) vulernabilities are mitigated by
clearing the affected CPU buffers. The mechanism for clearing the buffers
uses the unused and obsolete VERW instruction in combination with a
microcode update which triggers a CPU buffer clear when VERW is executed.
Provide a inline function with the assembly magic. The argument of the VERW
instruction must be a memory operand as documented:
"MD_CLEAR enumerates that the memory-operand variant of VERW (for
example, VERW m16) has been extended to also overwrite buffers affected
by MDS. This buffer overwriting functionality is not guaranteed for the
register operand variant of VERW."
Documentation also recommends to use a writable data segment selector:
"The buffer overwriting occurs regardless of the result of the VERW
permission check, as well as when the selector is null or causes a
descriptor load segment violation. However, for lowest latency we
recommend using a selector that indicates a valid writable data
segment."
Add x86 specific documentation about MDS and the internal workings of the
mitigation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Jon Masters <jcm@redhat.com>
Tested-by: Jon Masters <jcm@redhat.com>
[bwh: Backported to 4.9: add the "Architecture-specific documentation"
section to the index]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'Documentation/index.rst')
| -rw-r--r-- | Documentation/index.rst | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/Documentation/index.rst b/Documentation/index.rst index 213399aac757..18b2484d19ef 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -20,6 +20,17 @@ Contents: gpu/index 80211/index +Architecture-specific documentation +----------------------------------- + +These books provide programming details about architecture-specific +implementation. + +.. toctree:: + :maxdepth: 2 + + x86/index + Indices and tables ================== |