Messages in this thread | | | From | Xin Li <> | Subject | [PATCH 0/6] Enable LKGS instruction | Date | Thu, 6 Oct 2022 08:40:35 -0700 |
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LKGS instruction is introduced with Intel FRED (flexible return and event delivery) specification https://cdrdv2.intel.com/v1/dl/getContent/678938.
LKGS is independent of FRED, so we enable it as a standalone CPU feature.
LKGS behaves like the MOV to GS instruction except that it loads the base address into the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s descriptor cache, which is exactly what Linux kernel does to load user level GS base. Thus, with LKGS, there is no need to SWAPGS away from the kernel GS base.
H. Peter Anvin (Intel) (6): x86/cpufeature: add cpu feature bit for LKGS x86/opcode: add LKGS instruction to x86-opcode-map x86/gsseg: make asm_load_gs_index() take an u16 x86/gsseg: move local_irq_save/restore() into asm_load_gs_index() x86/gsseg: move load_gs_index() to its own header file x86/gsseg: use the LKGS instruction if available for load_gs_index()
arch/x86/entry/entry_64.S | 28 +++++++++--- arch/x86/ia32/ia32_signal.c | 1 + arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/gsseg.h | 58 ++++++++++++++++++++++++ arch/x86/include/asm/mmu_context.h | 1 + arch/x86/include/asm/special_insns.h | 21 --------- arch/x86/kernel/paravirt.c | 1 + arch/x86/kernel/tls.c | 1 + arch/x86/lib/x86-opcode-map.txt | 1 + tools/arch/x86/include/asm/cpufeatures.h | 1 + tools/arch/x86/lib/x86-opcode-map.txt | 1 + 11 files changed, 88 insertions(+), 27 deletions(-) create mode 100644 arch/x86/include/asm/gsseg.h
-- 2.34.1
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