From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Zhang Lei <zhang.lei@jp.fujitsu.com>,
Andre Przywara <andre.przywara@arm.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 7/7] arm64/sve: Don't zero non-FPSIMD register state on syscall by default
Date: Wed, 20 Jul 2022 15:31:34 +0100 [thread overview]
Message-ID: <YtgRxh1L7VrHvjDl@sirena.org.uk> (raw)
In-Reply-To: <878rooyvvv.wl-maz@kernel.org>
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On Wed, Jul 20, 2022 at 10:29:56AM +0100, Marc Zyngier wrote:
> Mark Brown <broonie@kernel.org> wrote:
> > it. Marc Zyngier has previously noted publicly the current behaviour
> > being a consideration in the context of discusion of optimisation ideas
> > like this one, I was a bit surprised that he commented on an earlier
> > patch in the series but not this one.
> Just because I don't repeat myself doesn't mean I changed my mind. I
> still don't buy the ABI change, as there is already a large(-ish) body
> of SW that assumes the current semantics.
Your previous comments (or at least the ones that I saw) weren't *quite*
that definitive.
I'm unconvinced about us actually having a large body of software at
this point, it's only potentially things that directly do syscalls in
the middle of SVE using functions and never get run with qemu user mode
- that could definitely be a thing, but let's not overstate it.
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WARNING: multiple messages have this Message-ID (diff)
From: Mark Brown <broonie@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Zhang Lei <zhang.lei@jp.fujitsu.com>,
James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Andre Przywara <andre.przywara@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Mark Rutland <mark.rutland@arm.com>
Subject: Re: [PATCH v2 7/7] arm64/sve: Don't zero non-FPSIMD register state on syscall by default
Date: Wed, 20 Jul 2022 15:31:34 +0100 [thread overview]
Message-ID: <YtgRxh1L7VrHvjDl@sirena.org.uk> (raw)
In-Reply-To: <878rooyvvv.wl-maz@kernel.org>
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On Wed, Jul 20, 2022 at 10:29:56AM +0100, Marc Zyngier wrote:
> Mark Brown <broonie@kernel.org> wrote:
> > it. Marc Zyngier has previously noted publicly the current behaviour
> > being a consideration in the context of discusion of optimisation ideas
> > like this one, I was a bit surprised that he commented on an earlier
> > patch in the series but not this one.
> Just because I don't repeat myself doesn't mean I changed my mind. I
> still don't buy the ABI change, as there is already a large(-ish) body
> of SW that assumes the current semantics.
Your previous comments (or at least the ones that I saw) weren't *quite*
that definitive.
I'm unconvinced about us actually having a large body of software at
this point, it's only potentially things that directly do syscalls in
the middle of SVE using functions and never get run with qemu user mode
- that could definitely be a thing, but let's not overstate it.
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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-07-20 14:31 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-20 12:41 [PATCH v2 0/7] arm64/sve: Clean up KVM integration and optimise syscalls Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 1/7] KVM: arm64: Discard any SVE state when entering KVM guests Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 2/7] arm64/fpsimd: Track the saved FPSIMD state type separately to TIF_SVE Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-07-11 9:40 ` Marc Zyngier
2022-07-11 9:40 ` Marc Zyngier
2022-07-11 11:39 ` Mark Brown
2022-07-11 11:39 ` Mark Brown
2022-07-11 14:33 ` Marc Zyngier
2022-07-11 14:33 ` Marc Zyngier
2022-07-11 15:53 ` Mark Brown
2022-07-11 15:53 ` Mark Brown
2022-07-20 9:40 ` Marc Zyngier
2022-07-20 9:40 ` Marc Zyngier
2022-07-20 13:51 ` Mark Brown
2022-07-20 13:51 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 3/7] arm64/fpsimd: Have KVM explicitly say which FP registers to save Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 4/7] arm64/fpsimd: Stop using TIF_SVE to manage register saving in KVM Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 5/7] arm64/fpsimd: Load FP state based on recorded data type Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 6/7] arm64/sve: Leave SVE enabled on syscall if we don't context switch Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-06-20 12:41 ` [PATCH v2 7/7] arm64/sve: Don't zero non-FPSIMD register state on syscall by default Mark Brown
2022-06-20 12:41 ` Mark Brown
2022-07-19 17:35 ` Catalin Marinas
2022-07-19 17:35 ` Catalin Marinas
2022-07-19 19:35 ` Mark Brown
2022-07-19 19:35 ` Mark Brown
2022-07-20 9:20 ` Will Deacon
2022-07-20 9:20 ` Will Deacon
2022-07-20 12:32 ` Mark Brown
2022-07-20 12:32 ` Mark Brown
2022-07-20 9:29 ` Marc Zyngier
2022-07-20 9:29 ` Marc Zyngier
2022-07-20 14:31 ` Mark Brown [this message]
2022-07-20 14:31 ` Mark Brown
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