[MODERATED] [PATCH 0/2] v3 more sampling fun 0

From: mark gross <[email protected]>
Subject: [PATCH 0/2] V3: more sampling funn

This is a significantly reworked version of the mitigation control   I think
I've addressed all the high quality feedback give on the first 2 versions.

This version of the mitigation no longer needs to change the structure of
cpu_vuln_whitelist as it creates a similar "affected_processors" list.

--- 

Special Register Buffer Data Sampling is a sampling type of vulnerability that
leaks data across cores sharing the HW-RNG for vulnerable processors.

This leak is fixed by a microcode update and is enabled by default.

This new microcode serializes processor access during execution of RDRAND or
RDSEED. It ensures that the shared buffer is overwritten before it is released
for reuse.

The mitigation impacts the throughput of the RDRAND and RDSEED instructions and
latency of RT processing running on the socket while executing RDRAND or
RDSEED.  The micro benchmark of calling RDRAND many times shows a slowdown.

This patch set enables kernel command line control of this mitigation and
exports vulnerability and mitigation status.

This patch set includes 2 patches:
The fist patch enables the command line control of the mitigation as well as
the sysfs export of vulnerability status.

The second patch has the Documentation/admin-guide/hw-vuln documentation for the
issue and the control over the mitigation.

The microcode defaults to enabling the mitigation.


mark gross (2):
  x86/speculation: Special Register Buffer Data Sampling (SRBDS)
    mitigation control.
  x86/speculation: SRBDS vulnerability and mitigation documentation

 Documentation/admin-guide/hw-vuln/index.rst   |   2 +
 .../special-register-buffer-data-sampling.rst | 145 ++++++++++++++++++
 .../admin-guide/kernel-parameters.txt         |  11 ++
 arch/x86/include/asm/cpu_device_id.h          |  12 ++
 arch/x86/include/asm/cpufeatures.h            |   2 +
 arch/x86/include/asm/msr-index.h              |   4 +
 arch/x86/kernel/cpu/bugs.c                    | 110 +++++++++++++
 arch/x86/kernel/cpu/common.c                  |  41 +++++
 arch/x86/kernel/cpu/cpu.h                     |  13 ++
 arch/x86/kernel/cpu/intel.c                   |   2 +
 arch/x86/kernel/cpu/match.c                   |  26 ++++
 drivers/base/cpu.c                            |   8 +
 12 files changed, 376 insertions(+)
 create mode 100644 Documentation/admin-guide/hw-vuln/special-register-buffer-data-sampling.rst

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2.17.1