From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 9 Jun 2020 16:30:21 +0000 (-0700)
Subject: Merge branch 'x86/srbds' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
X-Git-Tag: v5.8-rc1~85
X-Git-Url: http://git.samba.org/samba.git/?a=commitdiff_plain;h=8b4d37db9a566deaf22065ba1ba9b19c9fb964b4;p=sfrench%2Fcifs-2.6.git

Merge branch 'x86/srbds' of git://git./linux/kernel/git/tip/tip

Pull x86 srbds fixes from Thomas Gleixner:
 "The 9th episode of the dime novel "The performance killer" with the
  subtitle "Slow Randomizing Boosts Denial of Service".

  SRBDS is an MDS-like speculative side channel that can leak bits from
  the random number generator (RNG) across cores and threads. New
  microcode serializes the processor access during the execution of
  RDRAND and RDSEED. This ensures that the shared buffer is overwritten
  before it is released for reuse. This is equivalent to a full bus
  lock, which means that many threads running the RNG instructions in
  parallel have the same effect as the same amount of threads issuing a
  locked instruction targeting an address which requires locking of two
  cachelines at once.

  The mitigation support comes with the usual pile of unpleasant
  ingredients:

   - command line options

   - sysfs file

   - microcode checks

   - a list of vulnerable CPUs identified by model and stepping this
     time which requires stepping match support for the cpu match logic.

   - the inevitable slowdown of affected CPUs"

* branch 'x86/srbds' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/speculation: Add Ivy Bridge to affected list
  x86/speculation: Add SRBDS vulnerability and mitigation documentation
  x86/speculation: Add Special Register Buffer Data Sampling (SRBDS) mitigation
  x86/cpu: Add 'table' argument to cpu_matches()
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