Messages in this thread | | | From | "Chang S. Bae" <> | Subject | [PATCH 00/23] x86: Support Intel Advanced Matrix Extensions (part 4) | Date | Thu, 21 Oct 2021 15:55:04 -0700 |
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This is the last part of the effort to support AMX. This series follows the KVM part: https://lore.kernel.org/lkml/20211017151447.829495362@linutronix.de/
With AMX the FPU register state buffer which is part of task_struct::thread::fpu is not going to be extended unconditionally for all tasks on an AMX enabled system as that would waste minimum 8K per task.
AMX provides a mechanism to trap on first use. That trap will be utilized to allocate a larger register state buffer when the task (process) has permissions to use it. The default buffer task_struct will only carry states up to AVX512.
The cost of XFD switching only matters for an AMX-enabled system. With the cleanup of the KVM FPU handling, host-side XFD/AMX is completely independent of guest-side XFD/AMX.
The per-task feature and size information helps to support dynamic features organically compared to the old versions.
Each task has a unique sigframe length with dynamic features. sigaltstack() has a new size checker to support a per-task sigframe size.
This version also fixes the syscall implementation and the XFD state switching on hot paths.
Here is a summary of patches:
- At first, add arch-specific sigaltstack size check
- Establish a set of new syscalls to control dynamic XSTATE components
- Update infrastructure to prepare dynamic features
- Support XFD state and switching, and add buffer reallocation helpers
- Finally, enable AMX with XFD #NM handling
This series is based on:
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu-3-kvm
and a revision of the version in the tglx tree -- some bug fixes, polish, and addressing Dave Hansen's feedback (noted on each patch):
git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/fpu
This comes with a large selftest suite which is going to be posted separately. A preview along with the full series is available here:
git://github.com/intel/amx-linux.git amx
Thanks, Chang
Chang S. Bae (15): x86/fpu/xstate: Provide xstate_calculate_size() x86/arch_prctl: Add controls for dynamic XSTATE components x86/fpu/signal: Prepare for variable sigframe length x86/fpu: Reset permission and fpstate on exec() x86/cpufeatures: Add eXtended Feature Disabling (XFD) feature bit x86/msr-index: Add MSRs for XFD x86/fpu: Add XFD state to fpstate x86/fpu: Update XFD state where required x86/fpu/xstate: Add XFD #NM handler x86/fpu/xstate: Add fpstate_realloc()/free() x86/fpu/xstate: Prepare XSAVE feature table for gaps in state component numbers x86/fpu/amx: Define AMX state components and have it used for boot-time checks x86/fpu: Calculate the default sizes independently x86/fpu: Add XFD handling for dynamic states x86/fpu/amx: Enable the AMX feature in 64-bit mode
Thomas Gleixner (8): signal: Add an optional check for altstack size x86/signal: Implement sigaltstack size validation x86/fpu: Add members to struct fpu to cache permission information x86/fpu: Add fpu_state_config::legacy_features x86/fpu: Add basic helpers for dynamically enabled features x86/signal: Use fpu::__state_user_size for sigalt stack validation x86/fpu: Prepare fpu_clone() for dynamically enabled features x86/fpu: Add sanity checks for XFD
.../admin-guide/kernel-parameters.txt | 9 + arch/Kconfig | 3 + arch/x86/Kconfig | 17 + arch/x86/include/asm/cpufeatures.h | 2 + arch/x86/include/asm/fpu/api.h | 11 + arch/x86/include/asm/fpu/sched.h | 2 +- arch/x86/include/asm/fpu/types.h | 88 +++ arch/x86/include/asm/fpu/xstate.h | 21 +- arch/x86/include/asm/msr-index.h | 2 + arch/x86/include/asm/proto.h | 2 +- arch/x86/include/uapi/asm/prctl.h | 4 + arch/x86/kernel/cpu/cpuid-deps.c | 2 + arch/x86/kernel/fpu/context.h | 2 + arch/x86/kernel/fpu/core.c | 93 ++- arch/x86/kernel/fpu/init.c | 9 +- arch/x86/kernel/fpu/internal.h | 3 - arch/x86/kernel/fpu/signal.c | 70 +-- arch/x86/kernel/fpu/xstate.c | 566 ++++++++++++++++-- arch/x86/kernel/fpu/xstate.h | 61 +- arch/x86/kernel/process.c | 21 +- arch/x86/kernel/signal.c | 64 +- arch/x86/kernel/traps.c | 38 ++ include/linux/signal.h | 6 + kernel/signal.c | 35 +- 24 files changed, 1008 insertions(+), 123 deletions(-)
base-commit: 672f086122b67b299aa89c6b5f647c20ef84157f -- 2.17.1
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