[MODERATED] [PATCH v2 0/2] v2: more sampling fun 0

From: mark gross <[email protected]>
Subject: [PATCH v2 0/2] more sampling fun

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 bechmark of calling RDRAND many times shows a 10x 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 first patch updates cpu_vuln_whitelist
with support for a 16 bit field for enumerating based on stepping as well as
vendor, family, model.

The second patch enables the command line control of the mitigation as well as
the sysfs export of vulnerability status.

The documentation patch is pending on the official white paper to be complete
such that I can make sure the in tree documentation is consistent with the
white paper.

The microcode defaults to enabling the mitigation.

changes since last version:
use GENMASK is most places recomended by Ben.
Fixed sysfs reporting issue associated with TSX=on case.

The next version is pending white paper finalization.  The disclosure of this
issues is coming in May.

mark gross (2):
  Add capability to specify a range of steppings in the vulnerability
    white list structure.
  WIP SRBDS mitigation enabling.

 arch/x86/include/asm/cpu_device_id.h | 12 ++++
 arch/x86/include/asm/cpufeatures.h   |  3 +
 arch/x86/include/asm/msr-index.h     |  4 ++
 arch/x86/kernel/cpu/bugs.c           | 84 ++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/common.c         | 52 ++++++++++++-----
 arch/x86/kernel/cpu/cpu.h            | 10 ++++
 arch/x86/kernel/cpu/intel.c          |  2 +
 arch/x86/kernel/cpu/match.c          | 26 +++++++++
 drivers/base/cpu.c                   |  8 +++
 9 files changed, 187 insertions(+), 14 deletions(-)

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2.17.1