diff options
| author |   Xiaoyao Li <xiaoyao.li@intel.com> | 2020-03-25 11:09:24 +0800 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2020-03-27 11:43:30 +0100 |
| commit | a6a60741035bb48ca8d9f92a138958818148064c (patch) | |
| tree | c4ad4d6fc86dd4ef0e3fc15b753db88742bc60bb /arch/x86/include/asm/thread_info.h | |
| parent | x86/split_lock: Rework the initialization flow of split lock detection (diff) | |
| download | linux-dev-a6a60741035bb48ca8d9f92a138958818148064c.tar.xz linux-dev-a6a60741035bb48ca8d9f92a138958818148064c.zip | |
x86/split_lock: Avoid runtime reads of the TEST_CTRL MSR
In a context switch from a task that is detecting split locks to one that
is not (or vice versa) we need to update the TEST_CTRL MSR. Currently this
is done with the common sequence:
read the MSR
flip the bit
write the MSR
in order to avoid changing the value of any reserved bits in the MSR.
Cache unused and reserved bits of TEST_CTRL MSR with SPLIT_LOCK_DETECT bit
cleared during initialization, so we can avoid an expensive RDMSR
instruction during context switch.
Suggested-by: Sean Christopherson <sean.j.christopherson@intel.com>
Originally-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200325030924.132881-3-xiaoyao.li@intel.com
Diffstat (limited to 'arch/x86/include/asm/thread_info.h')
0 files changed, 0 insertions, 0 deletions