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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-26 10:09:38 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-04-26 10:09:38 -0700 |
| commit | 64f8e73de08d11cbe01347340db95b4011872ec5 (patch) | |
| tree | f1a3574482457a91d4eea2af9bc3aeb7b8c26bae /arch/x86/include/asm/msr-index.h | |
| parent | eea2647e74cd7bd5d04861ce55fa502de165de14 (diff) | |
| parent | ebca17707e38f2050b188d837bd4646b29a1b0c2 (diff) | |
| download | linux-64f8e73de08d11cbe01347340db95b4011872ec5.tar.gz | |
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
Diffstat (limited to 'arch/x86/include/asm/msr-index.h')
| -rw-r--r-- | arch/x86/include/asm/msr-index.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h index 45029354e0a8..fe335d8c1676 100644 --- a/arch/x86/include/asm/msr-index.h +++ b/arch/x86/include/asm/msr-index.h @@ -265,6 +265,7 @@ #define DEBUGCTLMSR_LBR (1UL << 0) /* last branch recording */ #define DEBUGCTLMSR_BTF_SHIFT 1 #define DEBUGCTLMSR_BTF (1UL << 1) /* single-step on branches */ +#define DEBUGCTLMSR_BUS_LOCK_DETECT (1UL << 2) #define DEBUGCTLMSR_TR (1UL << 6) #define DEBUGCTLMSR_BTS (1UL << 7) #define DEBUGCTLMSR_BTINT (1UL << 8) |