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From: Xin Li <xin3.li@intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
	dave.hansen@linux.intel.com, hpa@zytor.com
Subject: [PATCH 0/6] Enable LKGS instruction
Date: Thu,  6 Oct 2022 08:40:35 -0700	[thread overview]
Message-ID: <20221006154041.13001-1-xin3.li@intel.com> (raw)

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


             reply	other threads:[~2022-10-06 16:03 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-06 15:40 Xin Li [this message]
2022-10-06 15:40 ` [PATCH 1/6] x86/cpufeature: add cpu feature bit for LKGS Xin Li
2022-10-06 15:40 ` [PATCH 2/6] x86/opcode: add LKGS instruction to x86-opcode-map Xin Li
2022-10-06 15:40 ` [PATCH 3/6] x86/gsseg: make asm_load_gs_index() take an u16 Xin Li
2022-10-06 15:40 ` [PATCH 4/6] x86/gsseg: move local_irq_save/restore() into asm_load_gs_index() Xin Li
2022-10-07 14:50   ` Peter Zijlstra
2022-10-07 17:47     ` H. Peter Anvin
2022-10-06 15:40 ` [PATCH 5/6] x86/gsseg: move load_gs_index() to its own header file Xin Li
2022-10-07 15:40   ` Brian Gerst
2022-10-07 17:43     ` H. Peter Anvin
2022-10-07 22:41       ` Li, Xin3
2022-10-06 15:40 ` [PATCH 6/6] x86/gsseg: use the LKGS instruction if available for load_gs_index() Xin Li
2022-10-07 14:47   ` Peter Zijlstra
2022-10-07 17:45     ` H. Peter Anvin
2022-10-07 18:07       ` Li, Xin3
2022-10-07 18:49         ` H. Peter Anvin
2022-10-07 18:01     ` Li, Xin3
2022-10-07 19:24       ` Peter Zijlstra
2022-10-07 20:03         ` H. Peter Anvin
2022-10-07 20:23           ` Peter Zijlstra
2022-10-07 20:33             ` H. Peter Anvin
2022-10-08  5:32               ` Li, Xin3
2022-10-08  7:16                 ` H. Peter Anvin
2022-10-10  4:21                   ` Li, Xin3
2022-10-14  4:36               ` Li, Xin3
2022-10-07 14:52   ` Peter Zijlstra
2022-10-07 15:09   ` Peter Zijlstra
2022-10-08  5:31     ` Li, Xin3
2022-10-07 16:18   ` Brian Gerst
2022-10-08  5:40     ` Li, Xin3
2022-10-08 12:40       ` Brian Gerst
2022-10-10  4:32         ` Li, Xin3
2022-10-10  4:51           ` H. Peter Anvin
2022-10-10  7:53           ` Peter Zijlstra

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