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| author | Fenghua Yu <fenghua.yu@intel.com> | 2021-03-22 14:53:23 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2021-03-28 22:52:14 +0200 |
| commit | f21d4d3b97a8603567e5d4250bd75e8ebbd520af (patch) | |
| tree | 922b404df5341d99291fa1aa1294a933d77d2d8c /arch/x86 | |
| parent | Linux 5.12-rc4 (diff) | |
| download | linux-f21d4d3b97a8603567e5d4250bd75e8ebbd520af.tar.xz linux-f21d4d3b97a8603567e5d4250bd75e8ebbd520af.zip | |
x86/cpufeatures: Enumerate #DB for bus lock detection
A bus lock is acquired through either a split locked access to writeback
(WB) memory or any locked access to non-WB memory. This is typically >1000
cycles slower than an atomic operation within a cache line. It also
disrupts performance on other cores.
Some CPUs have the ability to notify the kernel by a #DB trap after a user
instruction acquires a bus lock and is executed. This allows the kernel to
enforce user application throttling or mitigation. Both breakpoint and bus
lock can trigger the #DB trap in the same instruction and the ordering of
handling them is the kernel #DB handler's choice.
The CPU feature flag to be shown in /proc/cpuinfo will be "bus_lock_detect".
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lore.kernel.org/r/20210322135325.682257-2-fenghua.yu@intel.com
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/cpufeatures.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index cc96e26d69f7..faec3d92d09b 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -354,6 +354,7 @@ #define X86_FEATURE_AVX512_VPOPCNTDQ (16*32+14) /* POPCNT for vectors of DW/QW */ #define X86_FEATURE_LA57 (16*32+16) /* 5-level page tables */ #define X86_FEATURE_RDPID (16*32+22) /* RDPID instruction */ +#define X86_FEATURE_BUS_LOCK_DETECT (16*32+24) /* Bus Lock detect */ #define X86_FEATURE_CLDEMOTE (16*32+25) /* CLDEMOTE instruction */ #define X86_FEATURE_MOVDIRI (16*32+27) /* MOVDIRI instruction */ #define X86_FEATURE_MOVDIR64B (16*32+28) /* MOVDIR64B instruction */ |