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    Subject[PATCH v18 00/15] arm64: MMU enabled kexec relocation
    Date
    Changelog:
    v18:
    - Addressed comments from Will Deacon
    - Added Acks from Catalin Marinas
    v17:
    - Merged with 5.15-rc1 as requested by Catalin Marinas
    - Added Tested-by: Pingfan Liu <piliu@redhat.com>
    v16:
    - Merged with 5.14-rc4
    v15:
    - Changed trans_pgd_copy_el2_vectors() to use vector table that
    only shared by kexec and hibernate. This way sync does not have
    dangling branch that was recently introduced. (Reported by Marc
    Zyngier)
    - Renamed is_hyp_callable() to is_hyp_nvhe() as requested by Marc
    Zyngier
    - Clean-ups, comment fixes.
    - Sync with upstream 368094df48e680fa51cedb68537408cfa64b788e
    v14:
    - Fixed a bug in "arm64: hyp-stub: Move elx_sync into the vectors"
    that was noticed by Marc Zyngier
    - Merged with upstream
    v13:
    - Fixed a hang on ThunderX2, thank you Pingfan Liu for reporting
    the problem. In relocation function we need civac not ivac, we
    need to clean data in addition to invalidating it.
    Since I was using ThunderX2 machine I also measured the new
    performance data on this large ARM64 server. The MMU improves
    kexec relocation 190 times on this machine! (see below for
    raw data). Saves 7.5s during CentOS kexec reboot.
    v12:
    - A major change compared to previous version. Instead of using
    contiguous VA range a copy of linear map is now used to perform
    copying of segments during relocation as it was agreed in the
    discussion of version 11 of this project.
    - In addition to using linear map, I also took several ideas from
    James Morse to better organize the kexec relocation:
    1. skip relocation function entirely if that is not needed
    2. remove the PoC flushing function since it is not needed
    anymore with MMU enabled.
    v11:
    - Fixed missing KEXEC_CORE dependency for trans_pgd.c
    - Removed useless "if(rc) return rc" statement (thank you Tyler Hicks)
    - Another 12 patches were accepted into maintainer's get.
    Re-based patches against:
    https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
    Branch: for-next/kexec
    v10:
    - Addressed a lot of comments form James Morse and from Marc Zyngier
    - Added review-by's
    - Synchronized with mainline

    v9: - 9 patches from previous series landed in upstream, so now series
    is smaller
    - Added two patches from James Morse to address idmap issues for machines
    with high physical addresses.
    - Addressed comments from Selin Dag about compiling issues. He also tested
    my series and got similar performance results: ~60 ms instead of ~580 ms
    with an initramfs size of ~120MB.
    v8:
    - Synced with mainline to keep series up-to-date
    v7:
    -- Addressed comments from James Morse
    - arm64: hibernate: pass the allocated pgdp to ttbr0
    Removed "Fixes" tag, and added Added Reviewed-by: James Morse
    - arm64: hibernate: check pgd table allocation
    Sent out as a standalone patch so it can be sent to stable
    Series applies on mainline + this patch
    - arm64: hibernate: add trans_pgd public functions
    Remove second allocation of tmp_pg_dir in swsusp_arch_resume
    Added Reviewed-by: James Morse <james.morse@arm.com>
    - arm64: kexec: move relocation function setup and clean up
    Fixed typo in commit log
    Changed kern_reloc to phys_addr_t types.
    Added explanation why kern_reloc is needed.
    Split into four patches:
    arm64: kexec: make dtb_mem always enabled
    arm64: kexec: remove unnecessary debug prints
    arm64: kexec: call kexec_image_info only once
    arm64: kexec: move relocation function setup
    - arm64: kexec: add expandable argument to relocation function
    Changed types of new arguments from unsigned long to phys_addr_t.
    Changed offset prefix to KEXEC_*
    Split into four patches:
    arm64: kexec: cpu_soft_restart change argument types
    arm64: kexec: arm64_relocate_new_kernel clean-ups
    arm64: kexec: arm64_relocate_new_kernel don't use x0 as temp
    arm64: kexec: add expandable argument to relocation function
    - arm64: kexec: configure trans_pgd page table for kexec
    Added invalid entries into EL2 vector table
    Removed KEXEC_EL2_VECTOR_TABLE_SIZE and KEXEC_EL2_VECTOR_TABLE_OFFSET
    Copy relocation functions and table into separate pages
    Changed types in kern_reloc_arg.
    Split into three patches:
    arm64: kexec: offset for relocation function
    arm64: kexec: kexec EL2 vectors
    arm64: kexec: configure trans_pgd page table for kexec
    - arm64: kexec: enable MMU during kexec relocation
    Split into two patches:
    arm64: kexec: enable MMU during kexec relocation
    arm64: kexec: remove head from relocation argument
    v6:
    - Sync with mainline tip
    - Added Acked's from Dave Young
    v5:
    - Addressed comments from Matthias Brugger: added review-by's, improved
    comments, and made cleanups to swsusp_arch_resume() in addition to
    create_safe_exec_page().
    - Synced with mainline tip.
    v4:
    - Addressed comments from James Morse.
    - Split "check pgd table allocation" into two patches, and moved to
    the beginning of series for simpler backport of the fixes.
    Added "Fixes:" tags to commit logs.
    - Changed "arm64, hibernate:" to "arm64: hibernate:"
    - Added Reviewed-by's
    - Moved "add PUD_SECT_RDONLY" earlier in series to be with other
    clean-ups
    - Added "Derived from:" to arch/arm64/mm/trans_pgd.c
    - Removed "flags" from trans_info
    - Changed .trans_alloc_page assumption to return zeroed page.
    - Simplify changes to trans_pgd_map_page(), by keeping the old
    code.
    - Simplify changes to trans_pgd_create_copy, by keeping the old
    code.
    - Removed: "add trans_pgd_create_empty"
    - replace init_mm with NULL, and keep using non "__" version of
    populate functions.
    v3:
    - Split changes to create_safe_exec_page() into several patches for
    easier review as request by Mark Rutland. This is why this series
    has 3 more patches.
    - Renamed trans_table to tans_pgd as agreed with Mark. The header
    comment in trans_pgd.c explains that trans stands for
    transitional page tables. Meaning they are used in transition
    between two kernels.
    v2:
    - Fixed hibernate bug reported by James Morse
    - Addressed comments from James Morse:
    * More incremental changes to trans_table
    * Removed TRANS_FORCEMAP
    * Added kexec reboot data for image with 380M in size.

    Enable MMU during kexec relocation in order to improve reboot performance.

    If kexec functionality is used for a fast system update, with a minimal
    downtime, the relocation of kernel + initramfs takes a significant portion
    of reboot.

    The reason for slow relocation is because it is done without MMU, and thus
    not benefiting from D-Cache.

    Performance data
    ----------------

    Cavium ThunderX2:
    Kernel Image size: 38M Iniramfs size: 46M Total relocation size: 84M
    MMU-disabled:
    relocation 7.489539915s
    MMU-enabled:
    relocation 0.03946095s

    Relocation performance is improved 190 times.

    Broadcom Stingray:
    For this experiment, the size of kernel plus initramfs is small, only 25M.
    If initramfs was larger, than the improvements would be greater, as time
    spent in relocation is proportional to the size of relocation.

    MMU-disabled::
    kernel shutdown 0.022131328s
    relocation 0.440510736s
    kernel startup 0.294706768s

    Relocation was taking: 58.2% of reboot time

    MMU-enabled:
    kernel shutdown 0.032066576s
    relocation 0.022158152s
    kernel startup 0.296055880s

    Now: Relocation takes 6.3% of reboot time

    Total reboot is x2.16 times faster.

    With bigger userland (fitImage 380M), the reboot time is improved by 3.57s,
    and is reduced from 3.9s down to 0.33s

    Previous approaches and discussions
    -----------------------------------
    v17: https://lore.kernel.org/lkml/20210916231325.125533-1-pasha.tatashin@soleen.com
    v16: https://lore.kernel.org/lkml/20210802215408.804942-1-pasha.tatashin@soleen.com
    v15: https://lore.kernel.org/lkml/20210609004419.936873-1-pasha.tatashin@soleen.com
    v14: https://lore.kernel.org/lkml/20210527150526.271941-1-pasha.tatashin@soleen.com
    v13: https://lore.kernel.org/lkml/20210408040537.2703241-1-pasha.tatashin@soleen.com
    v12: https://lore.kernel.org/lkml/20210303002230.1083176-1-pasha.tatashin@soleen.com
    v11: https://lore.kernel.org/lkml/20210127172706.617195-1-pasha.tatashin@soleen.com
    v10: https://lore.kernel.org/linux-arm-kernel/20210125191923.1060122-1-pasha.tatashin@soleen.com
    v9: https://lore.kernel.org/lkml/20200326032420.27220-1-pasha.tatashin@soleen.com
    v8: https://lore.kernel.org/lkml/20191204155938.2279686-1-pasha.tatashin@soleen.com
    v7: https://lore.kernel.org/lkml/20191016200034.1342308-1-pasha.tatashin@soleen.com
    v6: https://lore.kernel.org/lkml/20191004185234.31471-1-pasha.tatashin@soleen.com
    v5: https://lore.kernel.org/lkml/20190923203427.294286-1-pasha.tatashin@soleen.com
    v4: https://lore.kernel.org/lkml/20190909181221.309510-1-pasha.tatashin@soleen.com
    v3: https://lore.kernel.org/lkml/20190821183204.23576-1-pasha.tatashin@soleen.com
    v2: https://lore.kernel.org/lkml/20190817024629.26611-1-pasha.tatashin@soleen.com
    v1: https://lore.kernel.org/lkml/20190801152439.11363-1-pasha.tatashin@soleen.com

    Pasha Tatashin (15):
    arm64: kernel: add helper for booted at EL2 and not VHE
    arm64: trans_pgd: hibernate: Add trans_pgd_copy_el2_vectors
    arm64: hibernate: abstract ttrb0 setup function
    arm64: kexec: flush image and lists during kexec load time
    arm64: kexec: skip relocation code for inplace kexec
    arm64: kexec: Use dcache ops macros instead of open-coding
    arm64: kexec: pass kimage as the only argument to relocation function
    arm64: kexec: configure EL2 vectors for kexec
    arm64: kexec: relocate in EL1 mode
    arm64: kexec: use ld script for relocation function
    arm64: kexec: install a copy of the linear-map
    arm64: kexec: keep MMU enabled during kexec relocation
    arm64: kexec: remove the pre-kexec PoC maintenance
    arm64: kexec: remove cpu-reset.h
    arm64: trans_pgd: remove trans_pgd_map_page()

    arch/arm64/Kconfig | 2 +-
    arch/arm64/include/asm/assembler.h | 49 ++++++--
    arch/arm64/include/asm/kexec.h | 12 ++
    arch/arm64/include/asm/mmu_context.h | 24 ++++
    arch/arm64/include/asm/sections.h | 1 +
    arch/arm64/include/asm/trans_pgd.h | 14 ++-
    arch/arm64/include/asm/virt.h | 7 ++
    arch/arm64/kernel/asm-offsets.c | 11 ++
    arch/arm64/kernel/cpu-reset.S | 7 +-
    arch/arm64/kernel/cpu-reset.h | 32 -----
    arch/arm64/kernel/hibernate-asm.S | 72 -----------
    arch/arm64/kernel/hibernate.c | 49 ++------
    arch/arm64/kernel/machine_kexec.c | 177 ++++++++++++++-------------
    arch/arm64/kernel/relocate_kernel.S | 69 +++++------
    arch/arm64/kernel/sdei.c | 2 +-
    arch/arm64/kernel/vmlinux.lds.S | 19 +++
    arch/arm64/mm/Makefile | 1 +
    arch/arm64/mm/trans_pgd-asm.S | 65 ++++++++++
    arch/arm64/mm/trans_pgd.c | 84 ++++---------
    19 files changed, 357 insertions(+), 340 deletions(-)
    delete mode 100644 arch/arm64/kernel/cpu-reset.h
    create mode 100644 arch/arm64/mm/trans_pgd-asm.S

    --
    2.33.0.800.g4c38ced690-goog

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