I think my issue looks like the same.  Sometimes I just get spinning dots, and sometimes there is the message about doing an automatic repair below the spinning dots before it stops and uses 100% cpu.  I just did a git bisect:

# git bisect log
# bad: [1ab5eb4efb91a3d4569b0df6e824cc08ab4bd8ec] Update version for v2.10.0 release
# good: [6c02258e143700314ebf268dae47eb23db17d1cf] Update version for v2.9.0 release
git bisect start 'v2.10.0' 'v2.9.0'
# bad: [269c20b2bbd2aa8531e0cdc741fb166f290d7a2b] tests/qdict: check more get_try_int() cases
git bisect bad 269c20b2bbd2aa8531e0cdc741fb166f290d7a2b
# bad: [eba0161990af8509608332450ee7e338273cf5df] Merge remote-tracking branch 'rth/tags/pull-s390-20170512' into staging
git bisect bad eba0161990af8509608332450ee7e338273cf5df
# good: [9ea5ada76f34a0ef048b131c3a166d8564199bdb] audio: Use ARRAY_SIZE from qemu/osdep.h
git bisect good 9ea5ada76f34a0ef048b131c3a166d8564199bdb
# bad: [1effe6ad5eac1b2e50a077695ac801d172891d6a] Merge remote-tracking branch 'danpb/tags/pull-qcrypto-2017-05-09-1' into staging
git bisect bad 1effe6ad5eac1b2e50a077695ac801d172891d6a
# good: [f03f9f0c10dcfadee5811d43240f0a6af230f1ce] Merge remote-tracking branch 'cohuck/tags/s390x-3270-20170504' into staging
git bisect good f03f9f0c10dcfadee5811d43240f0a6af230f1ce
# good: [6c02258e143700314ebf268dae47eb23db17d1cf] qobject-input-visitor: Document full_name_nth()
git bisect good 6c02258e143700314ebf268dae47eb23db17d1cf
# bad: [95615ce5a1beffff1a5dd3597d8cb6ba83f0010e] vhost-scsi: create a vhost-scsi-common abstraction
git bisect bad 95615ce5a1beffff1a5dd3597d8cb6ba83f0010e
# bad: [31f5a726b59bda5580e2f9413867893501dd7d93] trace: add qemu mutex lock and unlock trace events
git bisect bad 31f5a726b59bda5580e2f9413867893501dd7d93
# bad: [49e00a18708e27c815828d9440d5c9300d19547c] use _Static_assert in QEMU_BUILD_BUG_ON
git bisect bad 49e00a18708e27c815828d9440d5c9300d19547c
# bad: [6103451aeb749e92bf7d730429985189c6921c32] hw/i386: Build-time assertion on pc/q35 reset register being identical.
git bisect bad 6103451aeb749e92bf7d730429985189c6921c32
# bad: [77af8a2b95b79699de650965d5228772743efe84] hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to improve guest OS support.
git bisect bad 77af8a2b95b79699de650965d5228772743efe84
# first bad commit: [77af8a2b95b79699de650965d5228772743efe84] hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to improve guest OS support.



77af8a2b95b79699de650965d5228772743efe84 is the first bad commit
commit 77af8a2b95b79699de650965d5228772743efe84
Author: Phil Dennis-Jordan <email address hidden>
Date:   Wed Mar 15 19:20:26 2017 +1300

    hw/i386: Use Rev3 FADT (ACPI 2.0) instead of Rev1 to improve guest OS support.

    This updates the FADT generated for x86/64 machine types from Revision 1 to 3. (Based on ACPI standard 2.0 instead of 1.0) The intention is to expose the reset register information to guest operating systems which require it, specifically OS X/macOS. Revision 1 FADTs do not contain the fields relating to the reset register.

    The new layout and contents remains backwards-compatible with operating systems which only support ACPI 1.0, as the existing fields are not modified by this change, as the 64-bit and 32-bit variants are allowed to co-exist according to the ACPI 2.0 standard. No regressions became apparent in tests with a range of Windows (XP-10) and Linux versions.

    The BIOS tables test suite's FADT checksum test has also been updated to reflect the new FADT layout and content.

    Signed-off-by: Phil Dennis-Jordan <email address hidden>
    Message-Id: <email address hidden>
    Signed-off-by: Paolo Bonzini <email address hidden>

:040000 040000 40063761c0b86f87e798e03ea48eff9ea0753425 6d2a94150cf1eafb16f0ccf6325281415fef64a6 M      hw
:040000 040000 fe3f1480a91b76fea238c765f0725e715932d96d 68f9368d8d78fd3267f609b603f97e8a74bdf528 M      include
:040000 040000 895e961b0a160100aa95b2f557cfe6b87a7d9bff 8ed08cef10fddee7814e38ad62be11371592a75a M      tests