[kvm-unit-tests PATCH v3 00/11] GIC fixes and improvements

[Alexandru Elisei <alexandru.elisei@arm.com>]

What started this series is Andre's SPI and group interrupts tests [1],
which prompted me to attempt to rewrite check_acked() so it's more flexible
and not so complicated to review. When I was doing that I noticed that the
message passing pattern for accesses to the acked, bad_irq and bad_sender
arrays didn't look quite right, and that turned into the first 7 patches of
the series. Even though the diffs are relatively small, they are not
trivial and the reviewer can skip them for the more palatable patches that
follow. I would still appreciate someone having a look at the memory
ordering fixes.

Patch #8 ("Split check_acked() into two functions") is where check_acked()
is reworked with an eye towards supporting different timeout values or
silent reporting without adding too many arguments to check_acked().

After changing the IPI tests, I turned my attention to the LPI tests, which
followed the same memory synchronization patterns, but invented their own
interrupt handler and testing functions. Instead of redoing the work that I
did for the IPI tests, I decided to convert the LPI tests to use the same
infrastructure.

For v2, I ran tests on the following machines and didn't see any issues:

- Ampere EMAG: all arm64 tests 10,000+ times (combined) under qemu and
  kvmtool.

- rockpro64: the arm GICv2 and GICv3 tests 10,000+ times under kvmtool (I
  chose kvmtool because it's faster than qemu); the arm64 gic tests (GICv2
  and GICv3) 5000+ times with qemu (didn't realize that ./run_tests.sh -g
  gic doesn't include the its tests); the arm64 GICv2 and GICv3 and ITS
  tests under kvmtool 13,000+ times.

For v3, because the changes weren't too big, I ran ./run_tests.sh for arm
and arm64 with qemu TCG on the my x86 machine; ran ./run_tests.sh for arm64
on rockpro64; and ran all the gic tests for arm and arm64 under kvmtool on
the rockpro64.

Changes in v3:

* Gathered Reviewed-by tags, thank you for the feedback!

* Reworked patch #2 and renamed it to "lib: arm/arm64: gicv2: Document
  existing barriers when sending IPIs". The necessary barriers were already in
  place in writel/readl. Dropped the R-b tag.

* Removed the GICv2 smp_rmb() barrier in #4 ("arm/arm64: gic: Remove unnecessary
  synchronization with stats_reset") because of the rmb() already present in
  readl() and reworded the commit message accordingly. Dropped the R-b tag.

* Commented the extra delay in wait_for_interrupts() for patch #8
  ("arm/arm64: gic: Split check_acked() into two functions").

* Minor change to the commit message for #10 ("arm64: gic: its-trigger:
  Don't trigger the LPI while it is pending") as per Andre's suggestion.

* Dropped patch #11 ("lib: arm64: gic-v3-its: Add wmb() barrier before INT
  command") because the wmb() was already present in __its_send_int() ->
  its_send_single_command() -> its_post_commands() -> writeq().

Changes in v2:

* Gathered Reviewed-by tags, thank you for the feedback!

* Modified code comments in #1 ("lib: arm/arm64: gicv3: Add missing barrier
  when sending IPIs") as per review suggestions.

* Moved the barrier() in gicv2_ipi_send_self() from #3 ("arm/arm64: gic:
  Remove memory synchronization from ipi_clear_active_handler()") to #2
  ("lib: arm/arm64: gicv2: Add missing barrier when sending IPIs").

* Renamed #3, changed "[..] Remove memory synchronization [..]" to
  "[..] Remove SMP synchronization [..]".

* Moved the removal of smp_rmb() from check_spurious() from #5 ("arm/arm64:
  gic: Use correct memory ordering for the IPI test") to patch #7
  ("arm/arm64: gic: Wait for writes to acked or spurious to complete").

* Fixed typos in #8 ("arm/arm64: gic: Split check_acked() into two
  functions").

* Patch #10 ("arm64: gic: its-trigger: Don't trigger the LPI while it is
  pending") is new. It was added to fix an issue found in v1 [2].

* Patch #11 ("lib: arm64: gic-v3-its: Add wmb() barrier before INT
  command") is also new; it was split from #12 ("arm64: gic: Use IPI test
  checking for the LPI tests") following review comments.

* Removed the now redundant call to stats_reset() from its_prerequisites()
  in #12 ("arm64: gic: Use IPI test checking for the LPI tests").

[1] https://lists.cs.columbia.edu/pipermail/kvmarm/2019-November/037853.html
[2] https://www.spinics.net/lists/kvm-arm/msg43628.html

Alexandru Elisei (11):
  lib: arm/arm64: gicv3: Add missing barrier when sending IPIs
  lib: arm/arm64: gicv2: Document existing barriers when sending IPIs
  arm/arm64: gic: Remove SMP synchronization from
    ipi_clear_active_handler()
  arm/arm64: gic: Remove unnecessary synchronization with stats_reset()
  arm/arm64: gic: Use correct memory ordering for the IPI test
  arm/arm64: gic: Check spurious and bad_sender in the active test
  arm/arm64: gic: Wait for writes to acked or spurious to complete
  arm/arm64: gic: Split check_acked() into two functions
  arm/arm64: gic: Make check_acked() more generic
  arm64: gic: its-trigger: Don't trigger the LPI while it is pending
  arm64: gic: Use IPI test checking for the LPI tests

 lib/arm/gic-v2.c |   6 +
 lib/arm/gic-v3.c |   6 +
 arm/gic.c        | 338 +++++++++++++++++++++++++----------------------
 3 files changed, 190 insertions(+), 160 deletions(-)

-- 
2.30.0