From: Hector Martin <marcan@marcan.st>
To: Zayd Qumsieh <zayd_qumsieh@apple.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Mark Brown <broonie@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Mateusz Guzik <mjguzik@gmail.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Marc Zyngier <maz@kernel.org>,
Oliver Upton <oliver.upton@linux.dev>,
Miguel Luis <miguel.luis@oracle.com>,
Joey Gouly <joey.gouly@arm.com>,
Christoph Paasch <cpaasch@apple.com>,
Kees Cook <keescook@chromium.org>,
Sami Tolvanen <samitolvanen@google.com>,
Baoquan He <bhe@redhat.com>,
Lecopzer Chen <lecopzer.chen@mediatek.com>,
Joel Granados <j.granados@samsung.com>,
Dawei Li <dawei.li@shingroup.cn>,
Andrew Morton <akpm@linux-foundation.org>,
Florent Revest <revest@chromium.org>,
David Hildenbrand <david@redhat.com>,
Stefan Roesch <shr@devkernel.io>,
Andy Chiu <andy.chiu@sifive.com>,
Josh Triplett <josh@joshtriplett.org>,
Oleg Nesterov <oleg@redhat.com>, Helge Deller <deller@gmx.de>,
Zev Weiss <zev@bewilderbeest.net>,
Ondrej Mosnacek <omosnace@redhat.com>,
Miguel Ojeda <ojeda@kernel.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, Justin Lu <ih_justin@apple.com>,
Asahi Linux <asahi@lists.linux.dev>
Subject: Re: [PATCH 0/3] tso: aarch64: Expose TSO for virtualized linux on Apple Silicon
Date: Thu, 11 Apr 2024 08:23:23 +0900 [thread overview]
Message-ID: <f4f53335-eba9-4c71-b64d-ca2c65c29a74@marcan.st> (raw)
In-Reply-To: <20240410211652.16640-1-zayd_qumsieh@apple.com>
On 2024/04/11 6:16, Zayd Qumsieh wrote:
> x86 CPUs use a TSO memory model. Apple Silicon CPUs have the ability to
> selectively use a TSO memory model. This can be done by setting the
> ACTLR.TSOEN bit to 1. This feature is useful for x86 emulators, since it
> removes the need for emulators to insert memory barriers in order to abide
> by the TSO memory model. This patch series will add ACTLR.TSOEN support to
> virtualized linux on Apple Silicon machines. Userspace will be able to use
> a prctl to change the memory model of the CPU from the default ARM64 memory
> model to a TSO memory model.
>
> A simple test can be used to determine if the TSO memory model is in use.
> This must be done on Apple Silicon MacOS Sonoma version 14.4 or later,
> since earlier versions do not support modification of the TSOEN bit.
> https://github.com/saagarjha/TSOEnabler/blob/master/testtso/main.c
>
> This program will hang indefinitely if TSO is in use, and will crash almost
> immediately if it is not in use.
Well this is unexpected, given I talked to Justin Lu at Apple back in
December and I thought our plan was to work together on the series I've
had cooking in the Asahi tree [1] for a while now, which is actually
shipping in thousands of Asahi Linux systems in production and actually
already supported by the FEX-Emu project with our ABI. You CCed 30+
people, but not me nor the asahi@lists.linux.dev mailing list...
[1] https://github.com/AsahiLinux/linux/tree/bits/220-tso
Given that we're here now, I'll send out my series for review and see
what people think about that one.
>
> Zayd Qumsieh (3):
> tso: aarch64: allow linux kernel to read/write ACTLR.TSOEN
> tso: aarch64: context-switch tso bit on thread switch
> tso: aarch64: allow userspace to set tso bit using prctl
>
> arch/arm64/Kconfig | 19 +++++++++
> arch/arm64/include/asm/processor.h | 4 ++
> arch/arm64/include/asm/sysreg.h | 7 ++++
> arch/arm64/include/asm/tso.h | 19 +++++++++
> arch/arm64/kernel/Makefile | 2 +-
> arch/arm64/kernel/process.c | 61 +++++++++++++++++++++++++++++
> arch/arm64/kernel/tso.c | 62 ++++++++++++++++++++++++++++++
> include/uapi/linux/prctl.h | 9 +++++
> kernel/sys.c | 11 ++++++
> 9 files changed, 193 insertions(+), 1 deletion(-)
> create mode 100644 arch/arm64/include/asm/tso.h
> create mode 100644 arch/arm64/kernel/tso.c
>
- Hector
parent reply other threads:[~2024-04-10 23:32 UTC|newest]
Thread overview: expand[flat|nested] mbox.gz Atom feed
[parent not found: <20240410211652.16640-1-zayd_qumsieh@apple.com>]
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