From: Vladimir Murzin <vladimir.murzin@arm•com>
To: Mark Rutland <mark.rutland@arm•com>,
linux-arm-kernel@lists•infradead.org, kvmarm@lists•linux.dev
Cc: broonie@kernel•org, catalin.marinas@arm•com, james.morse@arm•com,
maz@kernel•org, oupton@kernel•org, tabba@google•com,
will@kernel•org
Subject: Re: [PATCH 00/18] arm64+KVM: FPSIMD/SVE/SME cleanups
Date: Thu, 28 May 2026 14:21:52 +0100 [thread overview]
Message-ID: <9f95f8df-8c28-4c8c-b13e-87bc366f43a8@arm.com> (raw)
In-Reply-To: <20260521132556.584676-1-mark.rutland@arm.com>
Hi Mark,
On 5/21/26 14:25, Mark Rutland wrote:
> Hi.
>
> This series cleans up low-level FPSIMD/SVE/SME state management code,
> making it easier to maintain and extend (e.g. adding SME support to
> KVM), and enabling better debugging (e.g. by making SVE/SME save/restore
> visible to KASAN and KCSAN).
>
> This is purely cleanup, there are NO bugs addressed by this series.
>
> The series aims to do a few key things:
>
> * Make it harder to mis-manage in-memory SVE state and SME state. These
> are given opaque types (struct sve_state and struct sme_state), and
> the (awkward) calling convention for saving/restoring SVE state is
> simplified to take a pointer to the base of the state rather than a
> pointer to the FFR within the state.
>
> * Minimize duplications between KVM and the rest of the kernel. The
> FPSIMD/SVE/SME routines are moved to inline assembly such that the
> same helper functions can be used everywhere, without the need to wrap
> assembly macros.
>
> * Make the code easier to follow. Assembly sequences are minimized to
> avoid address generation and control-flow that can be written more
> clearly in C. Awkward assembly macros are removed where possible.
>
> * Make it easier to debug state management. Explicit instrumentation is
> added to the save/restore functions so that KASAN and KCSAN can detect
> memory safety issues and concurrency issues.
>
> This instrumentation is inhibited for nVHE hyp objects, and does not
> adversely affect KVM. I've confirmed by looking at compiler flags
> during the build, and disassembling the relevant object files.
>
> * Remove unnecessary code. By relying on assembler support for SVE and
> SME we can remove awkward assembly macros, making the code
> significantly simpler and easier to read.
>
> I've compile-tested this with a variety of toolchains:
>
> * GCC 8.1.0 + binutils 2.30
> * GCC 11.1.0 + binutils 2.36.1
> * GCC 12.1.0 + binutils 2.38
> * GCC 15.2.0 + binutils 2.45
> * LLVM 15.0.7
> * LLVM 21.1.8
>
> I've boot-tested on an SVE+SME capable model, both with KASAN enabled
> and without KASAN enabled. All the FPSIMD/SVE/SME kselftests passed in
> both configurations, without any KASAN splats. Unfortunately, with KCSAN
> enabled, some tests hit timeouts (without any KCSAN splat), which I
> believe is simply due to the overhead of KCSAN rather than some adverse
> functional effect.
>
> I've boot-tested on an SVE+SME capable model, booting with KVM in each
> of:
>
> * VHE mode
> * hVHE mode
> * Protected mode
>
> In each case I've boot-tested a v7.0 defconfig guest, both with SVE and
> without SVE.
>
> Mark.
>
> Mark Rutland (18):
> KVM: arm64: Don't include <asm/fpsimdmacros.h>
> KVM: arm64: Don't override FFR save/restore argument
> KVM: arm64: pkvm: Save host FPMR in host cpu context
> KVM: arm64: pkvm: Remove struct cpu_sve_state
> arm64: fpsimd: Fold sve_init_regs() into do_sve_acc()
> arm64: fpsimd: Remove sve_set_vq() and sme_set_vq()
This may be out of scope for the series, but I noticed that
write_vl() and sve_cond_update_zcr_vq() might similarly benefit
from using sysreg_clear_set_s()
> arm64: fpsimd: Use assembler for SVE instructions
> arm64: fpsimd: Use assembler for baseline SME instructions
> arm64: fpsimd: Move sve_get_vl() and sme_get_vl() inline
> arm64: sysreg: Add FPCR and FPSR
> arm64: fpsimd: Split FPSR/FPCR from SVE save/restore
> arm64: fpsimd: Move fpsimd save/restore inline
> arm64: fpsimd: Use opaque type for SVE state
> arm64: fpsimd: Use opaque type for SME state
> arm64: fpsimd: Move SVE save/restore inline
> arm64: fpsimd: Move sve_flush_live() inline
> arm64: fpsimd: Move SME save/restore inline
> arm64: fpsimd: Remove <asm/fpsimdmacros.h>
>
> arch/arm64/Kconfig | 5 +
> arch/arm64/include/asm/fpsimd.h | 369 ++++++++++++++++++++++--
> arch/arm64/include/asm/fpsimdmacros.h | 357 -----------------------
> arch/arm64/include/asm/kvm_host.h | 27 +-
> arch/arm64/include/asm/kvm_hyp.h | 5 -
> arch/arm64/include/asm/kvm_pkvm.h | 3 +-
> arch/arm64/include/asm/processor.h | 7 +-
> arch/arm64/kernel/Makefile | 2 +-
> arch/arm64/kernel/entry-common.c | 8 +-
> arch/arm64/kernel/entry-fpsimd.S | 134 ---------
> arch/arm64/kernel/fpsimd.c | 90 +++---
> arch/arm64/kvm/arm.c | 16 +-
> arch/arm64/kvm/guest.c | 4 +-
> arch/arm64/kvm/hyp/entry.S | 1 -
> arch/arm64/kvm/hyp/fpsimd.S | 33 ---
> arch/arm64/kvm/hyp/include/hyp/switch.h | 23 +-
> arch/arm64/kvm/hyp/nvhe/Makefile | 2 +-
> arch/arm64/kvm/hyp/nvhe/hyp-main.c | 20 +-
> arch/arm64/kvm/hyp/nvhe/setup.c | 4 +-
> arch/arm64/kvm/hyp/vhe/Makefile | 2 +-
> arch/arm64/tools/sysreg | 45 +++
> 21 files changed, 480 insertions(+), 677 deletions(-)
> delete mode 100644 arch/arm64/include/asm/fpsimdmacros.h
> delete mode 100644 arch/arm64/kernel/entry-fpsimd.S
> delete mode 100644 arch/arm64/kvm/hyp/fpsimd.S
>
> -- 2.30.2
>
Cheers
Vladimir
next prev parent reply other threads:[~2026-05-28 13:22 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-21 13:25 [PATCH 00/18] arm64+KVM: FPSIMD/SVE/SME cleanups Mark Rutland
2026-05-21 13:25 ` [PATCH 01/18] KVM: arm64: Don't include <asm/fpsimdmacros.h> Mark Rutland
2026-05-26 14:18 ` Mark Brown
2026-05-27 10:10 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 02/18] KVM: arm64: Don't override FFR save/restore argument Mark Rutland
2026-05-26 14:27 ` Mark Brown
2026-05-27 10:16 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 03/18] KVM: arm64: pkvm: Save host FPMR in host cpu context Mark Rutland
2026-05-27 10:29 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 04/18] KVM: arm64: pkvm: Remove struct cpu_sve_state Mark Rutland
2026-05-27 11:58 ` Vladimir Murzin
2026-05-27 16:02 ` Mark Rutland
2026-05-27 16:11 ` Vladimir Murzin
2026-05-28 15:09 ` Mark Rutland
2026-05-28 15:12 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 05/18] arm64: fpsimd: Fold sve_init_regs() into do_sve_acc() Mark Rutland
2026-05-26 15:28 ` Mark Brown
2026-05-27 12:05 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 06/18] arm64: fpsimd: Remove sve_set_vq() and sme_set_vq() Mark Rutland
2026-05-26 15:42 ` Mark Brown
2026-05-27 12:50 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 07/18] arm64: fpsimd: Use assembler for SVE instructions Mark Rutland
2026-05-26 15:43 ` Mark Brown
2026-05-27 12:58 ` Vladimir Murzin
2026-05-27 16:10 ` Mark Rutland
2026-05-21 13:25 ` [PATCH 08/18] arm64: fpsimd: Use assembler for baseline SME instructions Mark Rutland
2026-05-26 15:45 ` Mark Brown
2026-05-27 13:06 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 09/18] arm64: fpsimd: Move sve_get_vl() and sme_get_vl() inline Mark Rutland
2026-05-26 15:47 ` Mark Brown
2026-05-27 13:18 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 10/18] arm64: sysreg: Add FPCR and FPSR Mark Rutland
2026-05-26 15:55 ` Mark Brown
2026-05-26 16:51 ` Mark Rutland
2026-05-26 16:54 ` Mark Brown
2026-05-21 13:25 ` [PATCH 11/18] arm64: fpsimd: Split FPSR/FPCR from SVE save/restore Mark Rutland
2026-05-26 16:28 ` Mark Brown
2026-05-27 13:51 ` Mark Rutland
2026-05-27 14:13 ` Mark Brown
2026-05-27 16:13 ` Mark Rutland
2026-05-27 13:44 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 12/18] arm64: fpsimd: Move fpsimd save/restore inline Mark Rutland
2026-05-26 16:44 ` Mark Brown
2026-05-28 16:15 ` Mark Rutland
2026-05-28 16:39 ` Mark Brown
2026-05-27 14:49 ` Vladimir Murzin
2026-05-27 15:34 ` Mark Rutland
2026-05-27 16:13 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 13/18] arm64: fpsimd: Use opaque type for SVE state Mark Rutland
2026-05-26 16:53 ` Mark Brown
2026-05-28 9:45 ` Vladimir Murzin
2026-05-28 16:25 ` Mark Rutland
2026-05-21 13:25 ` [PATCH 14/18] arm64: fpsimd: Use opaque type for SME state Mark Rutland
2026-05-26 16:56 ` Mark Brown
2026-05-28 9:51 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 15/18] arm64: fpsimd: Move SVE save/restore inline Mark Rutland
2026-05-27 12:29 ` Mark Brown
2026-05-28 10:39 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 16/18] arm64: fpsimd: Move sve_flush_live() inline Mark Rutland
2026-05-27 12:54 ` Mark Brown
2026-05-27 16:23 ` Mark Rutland
2026-05-28 10:49 ` Vladimir Murzin
2026-05-21 13:25 ` [PATCH 17/18] arm64: fpsimd: Move SME save/restore inline Mark Rutland
2026-05-26 14:08 ` Mark Rutland
2026-05-26 14:39 ` Vladimir Murzin
2026-05-26 15:28 ` Mark Rutland
2026-05-26 16:38 ` Mark Rutland
2026-05-27 9:00 ` Vladimir Murzin
2026-05-29 9:10 ` Mark Rutland
2026-05-28 12:30 ` Vladimir Murzin
2026-05-28 14:39 ` Mark Rutland
2026-05-21 13:25 ` [PATCH 18/18] arm64: fpsimd: Remove <asm/fpsimdmacros.h> Mark Rutland
2026-05-28 13:10 ` Vladimir Murzin
2026-05-27 8:07 ` [PATCH 00/18] arm64+KVM: FPSIMD/SVE/SME cleanups Marc Zyngier
2026-05-27 10:32 ` Mark Rutland
2026-05-27 14:36 ` Will Deacon
2026-05-28 13:21 ` Vladimir Murzin [this message]
2026-05-28 16:28 ` Mark Rutland
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