Linus Torvalds 64f8e73de0 Support for enhanced split lock detection:
Newer CPUs provide a second mechanism to detect operations with lock
   prefix which go accross a cache line boundary. Such operations have to
   take bus lock which causes a system wide performance degradation when
   these operations happen frequently.
 
   The new mechanism is not using the #AC exception. It triggers #DB and is
   restricted to operations in user space. Kernel side split lock access can
   only be detected by the #AC based variant. Contrary to the #AC based
   mechanism the #DB based variant triggers _after_ the instruction was
   executed. The mechanism is CPUID enumerated and contrary to the #AC
   version which is based on the magic TEST_CTRL_MSR and model/family based
   enumeration on the way to become architectural.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAmCGkr8THHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYodUKD/9tUXhInR7+1ykEHpMvdmSp48vqY3nc
 sKmT22pPl+OchnJ62mw3T8gKpBYVleJmcCaY2qVx7hfaVcWApLGJvX4tmfXmv422
 XDSJ6b8Os6wfgx5FR//I17z8ZtXnnuKkPrTMoRsQUw2qLq31y6fdQv+GW/cc1Kpw
 mengjmPE+HnpaKbtuQfPdc4a+UvLjvzBMAlDZPTBPKYrP4FFqYVnUVwyTg5aLVDY
 gHz4V8+b502RS/zPfTAtE3J848od+NmcUPdFlcG9DVA+hR0Rl0thvruCTFiD2vVh
 i9DJ7INof5FoJDEzh0dGsD7x+MB6OY8GZyHdUMeGgIRPtWkqrG52feQQIn2YYlaL
 fB3DlpNv7NIJ/0JMlALvh8S0tEoOcYdHqH+M/3K/zbzecg/FAo+lVo8WciGLPqWs
 ykUG5/f/OnlTvgB8po1ebJu0h0jHnoK9heWWXk9zWIRVDPXHFOWKW3kSbTTb3icR
 9hfjP/SNejpmt9Ju1OTwsgnV7NALIdVX+G5jyIEsjFl31Co1RZNYhHLFvi11FWlQ
 /ssvFK9O5ZkliocGCAN9+yuOnM26VqWSCE4fis6/2aSgD2Y4Gpvb//cP96SrcNAH
 u8eXNvGLlniJP3F3JImWIfIPQTrpvQhcU4eZ6NtviXqj/utQXX6c9PZ1PLYpcvUh
 9AWF8rwhT8X4oA==
 =lmi8
 -----END PGP SIGNATURE-----

Merge tag 'x86-splitlock-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 bus lock detection updates from Thomas Gleixner:
 "Support for enhanced split lock detection:

  Newer CPUs provide a second mechanism to detect operations with lock
  prefix which go accross a cache line boundary. Such operations have to
  take bus lock which causes a system wide performance degradation when
  these operations happen frequently.

  The new mechanism is not using the #AC exception. It triggers #DB and
  is restricted to operations in user space. Kernel side split lock
  access can only be detected by the #AC based variant.

  Contrary to the #AC based mechanism the #DB based variant triggers
  _after_ the instruction was executed. The mechanism is CPUID
  enumerated and contrary to the #AC version which is based on the magic
  TEST_CTRL_MSR and model/family based enumeration on the way to become
  architectural"

* tag 'x86-splitlock-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation/admin-guide: Change doc for split_lock_detect parameter
  x86/traps: Handle #DB for bus lock
  x86/cpufeatures: Enumerate #DB for bus lock detection
2021-04-26 10:09:38 -07:00
..
2021-03-18 15:31:53 +01:00
2020-03-30 19:14:28 -07:00
2020-11-24 16:47:49 +01:00
2021-03-18 15:31:53 +01:00
2021-03-18 15:31:53 +01:00
2021-03-18 15:31:53 +01:00
2021-03-18 15:31:53 +01:00
2019-11-12 16:21:15 +01:00
2021-03-18 15:31:53 +01:00
2019-11-12 16:21:15 +01:00
2021-03-18 15:31:53 +01:00
2021-02-21 13:31:43 -08:00
2020-06-02 10:59:12 -07:00
2020-08-20 13:12:58 +02:00
2021-03-18 15:31:53 +01:00
2020-06-11 15:54:31 -07:00
2020-07-27 14:31:07 -04:00
2020-07-27 14:31:07 -04:00
2021-03-18 15:31:53 +01:00
2020-08-04 14:47:45 -07:00
2020-12-14 17:34:12 -08:00