linux-kernel - [PATCH v5 0/2] Renovate memcpy_mcsafe with copy_mc_to

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Date:   Wed, 27 May 2020 16:16:02 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     tglx@...utronix.de, mingo@...hat.com
Cc:     Tony Luck <tony.luck@...el.com>, Vivek Goyal <vgoyal@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Borislav Petkov <bp@...en8.de>, stable@...r.kernel.org,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>,
        Paul Mackerras <paulus@...ba.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Erwin Tsaur <erwin.tsaur@...el.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Mikulas Patocka <mpatocka@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org, linux-nvdimm@...ts.01.org
Subject: [PATCH v5 0/2] Renovate memcpy_mcsafe with copy_mc_to_{user, kernel}

Changes since v4 [1]:
- Fix up .gitignore for PowerPC test artifacts (Michael)

- Collect Michael's Ack.

[1]: http://lore.kernel.org/r/159010126119.975921.6614194205409771984.stgit@dwillia2-desk3.amr.corp.intel.com

---

The primary motivation to go touch memcpy_mcsafe() is that the existing
benefit of doing slow "handle with care" copies is obviated on newer
CPUs. With that concern lifted it also obviates the need to continue to
update the MCA-recovery capability detection code currently gated by
"mcsafe_key". Now the old "mcsafe_key" opt-in to perform the copy with
concerns for recovery fragility can instead be made an opt-out from the
default fast copy implementation (enable_copy_mc_fragile()).

The discussion with Linus on the first iteration of this patch
identified that memcpy_mcsafe() was misnamed relative to its usage. The
new names copy_mc_to_user() and copy_mc_to_kernel() clearly indicate the
intended use case and lets the architecture organize the implementation
accordingly.

For both powerpc and x86 a copy_mc_generic() implementation is added as
the backend for these interfaces.

Patches are relative to tip/master.

---

Dan Williams (2):
      x86, powerpc: Rename memcpy_mcsafe() to copy_mc_to_{user,kernel}()
      x86/copy_mc: Introduce copy_mc_generic()


 arch/powerpc/Kconfig                               |    2 
 arch/powerpc/include/asm/string.h                  |    2 
 arch/powerpc/include/asm/uaccess.h                 |   40 +++--
 arch/powerpc/lib/Makefile                          |    2 
 arch/powerpc/lib/copy_mc_64.S                      |    4 
 arch/x86/Kconfig                                   |    2 
 arch/x86/Kconfig.debug                             |    2 
 arch/x86/include/asm/copy_mc_test.h                |   75 +++++++++
 arch/x86/include/asm/mcsafe_test.h                 |   75 ---------
 arch/x86/include/asm/string_64.h                   |   32 ----
 arch/x86/include/asm/uaccess.h                     |   21 +++
 arch/x86/include/asm/uaccess_64.h                  |   20 --
 arch/x86/kernel/cpu/mce/core.c                     |    8 -
 arch/x86/kernel/quirks.c                           |    9 -
 arch/x86/lib/Makefile                              |    1 
 arch/x86/lib/copy_mc.c                             |   64 ++++++++
 arch/x86/lib/copy_mc_64.S                          |  165 ++++++++++++++++++++
 arch/x86/lib/memcpy_64.S                           |  115 --------------
 arch/x86/lib/usercopy_64.c                         |   21 ---
 drivers/md/dm-writecache.c                         |   15 +-
 drivers/nvdimm/claim.c                             |    2 
 drivers/nvdimm/pmem.c                              |    6 -
 include/linux/string.h                             |    9 -
 include/linux/uaccess.h                            |    9 +
 include/linux/uio.h                                |   10 +
 lib/Kconfig                                        |    7 +
 lib/iov_iter.c                                     |   43 +++--
 tools/arch/x86/include/asm/mcsafe_test.h           |   13 --
 tools/arch/x86/lib/memcpy_64.S                     |  115 --------------
 tools/objtool/check.c                              |    5 -
 tools/perf/bench/Build                             |    1 
 tools/perf/bench/mem-memcpy-x86-64-lib.c           |   24 ---
 tools/testing/nvdimm/test/nfit.c                   |   48 +++---
 .../testing/selftests/powerpc/copyloops/.gitignore |    2 
 tools/testing/selftests/powerpc/copyloops/Makefile |    6 -
 .../selftests/powerpc/copyloops/copy_mc_64.S       |    1 
 .../selftests/powerpc/copyloops/memcpy_mcsafe_64.S |    1 
 37 files changed, 451 insertions(+), 526 deletions(-)
 rename arch/powerpc/lib/{memcpy_mcsafe_64.S => copy_mc_64.S} (98%)
 create mode 100644 arch/x86/include/asm/copy_mc_test.h
 delete mode 100644 arch/x86/include/asm/mcsafe_test.h
 create mode 100644 arch/x86/lib/copy_mc.c
 create mode 100644 arch/x86/lib/copy_mc_64.S
 delete mode 100644 tools/arch/x86/include/asm/mcsafe_test.h
 delete mode 100644 tools/perf/bench/mem-memcpy-x86-64-lib.c
 create mode 120000 tools/testing/selftests/powerpc/copyloops/copy_mc_64.S
 delete mode 120000 tools/testing/selftests/powerpc/copyloops/memcpy_mcsafe_64.S

base-commit: 229aaa8c059f2c908e0561453509f996f2b2d5c4