Thread (14 messages) 14 messages, 5 authors, 2025-09-15
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[PATCH v2 4/7] arm64/fpsimd: Don't warn when EFI execution context is preemptible

From: Ard Biesheuvel <hidden>
Date: 2025-09-05 13:30:52
Also in: linux-efi, lkml
Subsystem: arm64 port (aarch64 architecture), the rest · Maintainers: Catalin Marinas, Will Deacon, Linus Torvalds

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 c37f02d7194e..d26a02ea2bb9 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1933,11 +1933,11 @@ 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:
-- 
2.51.0.355.g5224444f11-goog

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