A recent submission to LKML introduced a CPU feature flag for a new Intel architecture Serializing Instruction, SERIALIZE [1]. Unlike the existing Serializing Instructions, this new instruction does not have side effects such as clobbering registers or exiting to a hypervisor.
As stated in the Intel "extensions" (ISE) manual [2], this instruction will appear first in Sapphire Rapids and Alder Lake. Andy Lutomirski suggested to use this instruction in sync_core() as it serves the very purpose of this function [3]. For completeness, I picked patch #3 from Cathy's series (and has become patch #1 here) [1]. Her series depends on such patch to build correctly. Maybe it can be merged independently while the discussion continues? Thanks and BR, Ricardo [1]. https://lore.kernel.org/kvm/1594088183-7187-1-git-send-email-cathy.zh...@intel.com/ [2]. https://software.intel.com/sites/default/files/managed/c5/15/architecture-instruction-set-extensions-programming-reference.pdf [3]. https://lore.kernel.org/kvm/CALCETrWudiF8G8r57r5i4JefuP5biG1kHg==0o8yxb-bys-...@mail.gmail.com/ Ricardo Neri (4): x86/cpufeatures: Add enumeration for SERIALIZE instruction x86/cpu: Relocate sync_core() to sync_core.h x86/cpu: Refactor sync_core() for readability x86/cpu: Use SERIALIZE in sync_core() when available arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/processor.h | 64 ---------------------- arch/x86/include/asm/special_insns.h | 4 ++ arch/x86/include/asm/sync_core.h | 80 ++++++++++++++++++++++++++++ arch/x86/kernel/alternative.c | 1 + arch/x86/kernel/cpu/mce/core.c | 1 + drivers/misc/sgi-gru/grufault.c | 1 + drivers/misc/sgi-gru/gruhandles.c | 1 + drivers/misc/sgi-gru/grukservices.c | 1 + 9 files changed, 90 insertions(+), 64 deletions(-) -- 2.17.1
