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From: Ard Biesheuvel <ardb+git@google.com>
To: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	 Ard Biesheuvel <ardb@kernel.org>, Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	 Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Peter Zijlstra <peterz@infradead.org>,
	 Catalin Marinas <catalin.marinas@arm.com>,
	Mark Brown <broonie@kernel.org>,
	 Pierre Gondois <Pierre.Gondois@arm.com>,
	Sami Mujawar <Sami.Mujawar@arm.com>
Subject: [PATCH v4 resend 3/7] arm64/fpsimd: Don't warn when EFI execution context is preemptible
Date: Wed, 15 Oct 2025 22:56:38 +0200	[thread overview]
Message-ID: <20251015205634.3820870-12-ardb+git@google.com> (raw)
In-Reply-To: <20251015205634.3820870-9-ardb+git@google.com>

From: Ard Biesheuvel <ardb@kernel.org>

Kernel mode FP/SIMD no longer requires preemption to be disabled, so
only warn on uses of FP/SIMD from preemptible context if the fallback
path is taken for cases where kernel mode NEON would not be allowed
otherwise.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm64/kernel/fpsimd.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index e3f8f51748bc..3d848c89604e 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1934,11 +1934,11 @@ void __efi_fpsimd_begin(void)
 	if (!system_supports_fpsimd())
 		return;
 
-	WARN_ON(preemptible());
-
 	if (may_use_simd()) {
 		kernel_neon_begin();
 	} else {
+		WARN_ON(preemptible());
+
 		/*
 		 * If !efi_sve_state, SVE can't be in use yet and doesn't need
 		 * preserving:
-- 
2.51.0.869.ge66316f041-goog



  parent reply	other threads:[~2025-10-15 21:01 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-10-15 20:56 [PATCH v4 resend 0/7] arm64: Make EFI calls preemptible Ard Biesheuvel
2025-10-15 20:56 ` [PATCH v4 resend 1/7] efi: Add missing static initializer for efi_mm::cpus_allowed_lock Ard Biesheuvel
2025-10-15 20:56 ` [PATCH v4 resend 2/7] efi/runtime-wrappers: Keep track of the efi_runtime_lock owner Ard Biesheuvel
2025-10-15 20:56 ` Ard Biesheuvel [this message]
2025-11-04 15:52   ` [PATCH v4 resend 3/7] arm64/fpsimd: Don't warn when EFI execution context is preemptible Will Deacon
2025-11-04 16:00     ` Ard Biesheuvel
2025-11-04 16:16       ` Will Deacon
2025-10-15 20:56 ` [PATCH v4 resend 4/7] arm64/fpsimd: Permit kernel mode NEON with IRQs off Ard Biesheuvel
2025-10-15 20:56 ` [PATCH v4 resend 5/7] arm64/efi: Drop efi_rt_lock spinlock from EFI arch wrapper Ard Biesheuvel
2025-10-15 20:56 ` [PATCH v4 resend 6/7] arm64/efi: Move uaccess en/disable out of efi_set_pgd() Ard Biesheuvel
2025-10-15 20:56 ` [PATCH v4 resend 7/7] arm64/efi: Call EFI runtime services without disabling preemption Ard Biesheuvel
2025-11-11 18:45 ` [PATCH v4 resend 0/7] arm64: Make EFI calls preemptible Catalin Marinas
2025-11-11 18:50   ` Ard Biesheuvel
2025-11-11 18:59     ` Catalin Marinas
2025-11-11 20:16 ` Catalin Marinas

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