[PATCH v8 00/19] Add support for 32-bit tasks on asymmetric AArch32 systems

Will Deacon
2021-06-02T16:49:41Z

Hi again folks,

Here is v8 of the asymmetric 32-bit support patches that I previously
posted here:

v1: https://lore.kernel.org/r/20201027215118.27003-1-will@kernel.org
v2: https://lore.kernel.org/r/20201109213023.15092-1-will@kernel.org
v3: https://lore.kernel.org/r/20201113093720.21106-1-will@kernel.org
v4: https://lore.kernel.org/r/20201124155039.13804-1-will@kernel.org
v5: https://lore.kernel.org/r/20201208132835.6151-1-will@kernel.org
v6: https://lore.kernel.org/r/20210518094725.7701-1-will@kernel.org
v7: https://lore.kernel.org/r/20210525151432.16875-1-will@kernel.org

There was also a nice LWN writeup in case you've forgotten what this is
about:

https://lwn.net/Articles/838339/

Changes since v7 include:

* Dropped the scheduler migration fix, as Valentin has kindly fixed
this separately in -tip:

https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?h=sched/core&id=475ea6c60279e9f2ddf7e4cf2648cd8ae0608361

* Dropped the freezer/ttwu changes, as Peter is rewriting that:

https://lore.kernel.org/r/YLYZv4v68OnAlx+3@hirez.programming.kicks-ass.net

* Reworded documentation wrt KVM behaviour [maz]

* Tidied up control flow in cpuset_cpus_allowed_fallback() [peterz]

* Fixed interaction with migrate_disable() [peterz]

* Don't ignore allocation failure in restrict_cpus_allowed_ptr() [peterz]

* Reordered the patches to put arm64 prep work first

* Added some more acks/reviewed-by tags

Cheers,

Will

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Qais Yousef <qais.yousef@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Quentin Perret <qperret@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: kernel-team@android.com

--->8

Will Deacon (19):
arm64: cpuinfo: Split AArch32 registers out into a separate struct
arm64: Allow mismatched 32-bit EL0 support
KVM: arm64: Kill 32-bit vCPUs on systems with mismatched EL0 support
arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs
sched: Introduce task_cpu_possible_mask() to limit fallback rq
selection
cpuset: Don't use the cpu_possible_mask as a last resort for cgroup v1
cpuset: Honour task_cpu_possible_mask() in guarantee_online_cpus()
sched: Reject CPU affinity changes based on task_cpu_possible_mask()
sched: Introduce task_struct::user_cpus_ptr to track requested
affinity
sched: Split the guts of sched_setaffinity() into a helper function
sched: Allow task CPU affinity to be restricted on asymmetric systems
sched: Introduce task_cpus_dl_admissible() to check proposed affinity
arm64: Implement task_cpu_possible_mask()
arm64: exec: Adjust affinity for compat tasks with mismatched 32-bit
EL0
arm64: Prevent offlining first CPU with 32-bit EL0 on mismatched
system
arm64: Advertise CPUs capable of running 32-bit applications in sysfs
arm64: Hook up cmdline parameter to allow mismatched 32-bit EL0
arm64: Remove logic to kill 32-bit tasks on 64-bit-only cores
Documentation: arm64: describe asymmetric 32-bit support

.../ABI/testing/sysfs-devices-system-cpu | 9 +
.../admin-guide/kernel-parameters.txt | 11 +
Documentation/arm64/asymmetric-32bit.rst | 155 ++++++++
Documentation/arm64/index.rst | 1 +
arch/arm64/include/asm/cpu.h | 44 +--
arch/arm64/include/asm/cpufeature.h | 8 +-
arch/arm64/include/asm/elf.h | 6 +-
arch/arm64/include/asm/mmu_context.h | 13 +
arch/arm64/kernel/cpufeature.c | 227 +++++++++---
arch/arm64/kernel/cpuinfo.c | 53 +--
arch/arm64/kernel/process.c | 44 ++-
arch/arm64/kvm/arm.c | 11 +-
arch/arm64/tools/cpucaps | 3 +-
include/linux/cpuset.h | 3 +-
include/linux/mmu_context.h | 11 +
include/linux/sched.h | 21 ++
init/init_task.c | 1 +
kernel/cgroup/cpuset.c | 49 ++-
kernel/fork.c | 2 +
kernel/sched/core.c | 334 ++++++++++++++----
kernel/sched/sched.h | 1 +
21 files changed, 819 insertions(+), 188 deletions(-)
create mode 100644 Documentation/arm64/asymmetric-32bit.rst

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2.32.0.rc0.204.g9fa02ecfa5-goog