From: Mark Rutland <mark.rutland@arm•com>
To: linux-arm-kernel@lists•infradead.org, kvmarm@lists•linux.dev
Cc: broonie@kernel•org, catalin.marinas@arm•com, james.morse@arm•com,
mark.rutland@arm•com, maz@kernel•org, oupton@kernel•org,
tabba@google•com, vladimir.murzin@arm•com, will@kernel•org
Subject: [PATCH v3 02/18] KVM: arm64: Don't override FFR save/restore argument
Date: Tue, 2 Jun 2026 16:11:34 +0100 [thread overview]
Message-ID: <20260602151150.925126-3-mark.rutland@arm.com> (raw)
In-Reply-To: <20260602151150.925126-1-mark.rutland@arm.com>
The __sve_save_state() and __sve_restore_state() functions take a
parameter describing whether to save/restore the FFR, but both functions
silently override this with '1'. This has always been benign (and
callers have all passed 'true' since the parameter was introduced), but
clearly this is not intentional.
Historically, the functions always saved/restored the FFR, and there was
no parameter to control this.
In v5.16, the sve_save and sve_load assembly macros used by
__sve_save_state() and __sve_restore_state() were changed to make
saving/restoring FFR optional. The implementations of __sve_save_state()
and __sve_restore_state() were changed to pass '1' to their respective
macros, and the prototypes of __sve_save_state() and
__sve_restore_state() were unchanged. See commit:
9f5848665788 ("arm64/sve: Make access to FFR optional")
In v6.10, the prototypes of __sve_save_state() and __sve_restore_state()
were changed to add 'save_ffr' and 'restore_ffr' parameters
respectively, but the implementations were not changed to stop passing 1
to their respective macros. All callers were changed to pass 'true' to
__sve_save_state() and __sve_restore_state(). See commit:
45f4ea9bcfe9 ("KVM: arm64: Fix prototype for __sve_save_state/__sve_restore_state")
This is all benign, but clearly unintentional, and it gets in the way of
cleaning up the FPSIMD/SVE/SME code. Remove the unnecessary overriding.
Signed-off-by: Mark Rutland <mark.rutland@arm•com>
Reviewed-by: Mark Brown <broonie@kernel•org>
Reviewed-by: Vladimir Murzin <vladimir.murzin@arm•com>
Cc: Catalin Marinas <catalin.marinas@arm•com>
Cc: Fuad Tabba <tabba@google•com>
Cc: James Morse <james.morse@arm•com>
Cc: Marc Zyngier <maz@kernel•org>
Cc: Oliver Upton <oupton@kernel•org>
Cc: Will Deacon <will@kernel•org>
---
arch/arm64/kvm/hyp/fpsimd.S | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/arm64/kvm/hyp/fpsimd.S b/arch/arm64/kvm/hyp/fpsimd.S
index e950875e31cee..6e16cbfc5df27 100644
--- a/arch/arm64/kvm/hyp/fpsimd.S
+++ b/arch/arm64/kvm/hyp/fpsimd.S
@@ -21,13 +21,11 @@ SYM_FUNC_START(__fpsimd_restore_state)
SYM_FUNC_END(__fpsimd_restore_state)
SYM_FUNC_START(__sve_restore_state)
- mov x2, #1
sve_load 0, x1, x2, 3
ret
SYM_FUNC_END(__sve_restore_state)
SYM_FUNC_START(__sve_save_state)
- mov x2, #1
sve_save 0, x1, x2, 3
ret
SYM_FUNC_END(__sve_save_state)
--
2.30.2
next prev parent reply other threads:[~2026-06-02 15:12 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-02 15:11 [PATCH v3 00/18] arm64+KVM: FPSIMD/SVE/SME cleanups Mark Rutland
2026-06-02 15:11 ` [PATCH v3 01/18] KVM: arm64: Don't include <asm/fpsimdmacros.h> Mark Rutland
2026-06-02 15:11 ` Mark Rutland [this message]
2026-06-02 15:36 ` [PATCH v3 02/18] KVM: arm64: Don't override FFR save/restore argument Mark Brown
2026-06-03 9:25 ` Mark Rutland
2026-06-02 15:11 ` [PATCH v3 03/18] KVM: arm64: pkvm: Save host FPMR in host cpu context Mark Rutland
2026-06-02 15:11 ` [PATCH v3 04/18] KVM: arm64: pkvm: Remove struct cpu_sve_state Mark Rutland
2026-06-02 15:11 ` [PATCH v3 05/18] arm64: fpsimd: Fold sve_init_regs() into do_sve_acc() Mark Rutland
2026-06-02 15:11 ` [PATCH v3 06/18] arm64: fpsimd: Remove sve_set_vq() and sme_set_vq() Mark Rutland
2026-06-02 15:11 ` [PATCH v3 07/18] arm64: fpsimd: Use assembler for SVE instructions Mark Rutland
2026-06-02 15:11 ` [PATCH v3 08/18] arm64: fpsimd: Use assembler for baseline SME instructions Mark Rutland
2026-06-02 15:11 ` [PATCH v3 09/18] arm64: fpsimd: Move sve_get_vl() and sme_get_vl() inline Mark Rutland
2026-06-02 15:11 ` [PATCH v3 10/18] arm64: sysreg: Add FPCR and FPSR Mark Rutland
2026-06-02 15:11 ` [PATCH v3 11/18] arm64: fpsimd: Split FPSR/FPCR from SVE save/restore Mark Rutland
2026-06-02 15:11 ` [PATCH v3 12/18] arm64: fpsimd: Move fpsimd save/restore inline Mark Rutland
2026-06-02 15:11 ` [PATCH v3 13/18] arm64: fpsimd: Use opaque type for SVE state Mark Rutland
2026-06-02 15:11 ` [PATCH v3 14/18] arm64: fpsimd: Use opaque type for SME state Mark Rutland
2026-06-02 15:11 ` [PATCH v3 15/18] arm64: fpsimd: Move SVE save/restore inline Mark Rutland
2026-06-02 15:11 ` [PATCH v3 16/18] arm64: fpsimd: Move sve_flush_live() inline Mark Rutland
2026-06-02 15:11 ` [PATCH v3 17/18] arm64: fpsimd: Move SME save/restore inline Mark Rutland
2026-06-02 15:30 ` Mark Brown
2026-06-02 15:11 ` [PATCH v3 18/18] arm64: fpsimd: Remove <asm/fpsimdmacros.h> Mark Rutland
2026-06-02 15:33 ` Mark Brown
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