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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>
Subject: [RFC PATCH 4/7] arm64/fpsimd: Don't warn when EFI execution context is preemptible
Date: Wed, 14 May 2025 19:43:44 +0200	[thread overview]
Message-ID: <20250514174339.1834871-13-ardb+git@google.com> (raw)
In-Reply-To: <20250514174339.1834871-9-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 ae2ea0196030..47a8706e26b7 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1975,11 +1975,11 @@ 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:
-- 
2.49.0.1101.gccaa498523-goog


  parent reply	other threads:[~2025-05-14 17:44 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-05-14 17:43 [RFC PATCH 0/7] arm64: Make EFI calls preemptible Ard Biesheuvel
2025-05-14 17:43 ` [RFC PATCH 1/7] efi: Add missing static initializer for efi_mm::cpus_allowed_lock Ard Biesheuvel
2025-05-14 17:43 ` [RFC PATCH 2/7] efi/runtime: Return success/failure from arch_efi_call_virt_setup() Ard Biesheuvel
2025-05-14 17:43 ` [RFC PATCH 3/7] efi/runtime: Deal with arch_efi_call_virt_setup() returning failure Ard Biesheuvel
2025-05-14 17:43 ` Ard Biesheuvel [this message]
2025-05-14 17:43 ` [RFC PATCH 5/7] arm64/efi: Use a semaphore to protect the EFI stack and FP/SIMD state Ard Biesheuvel
2025-05-14 17:43 ` [RFC PATCH 6/7] arm64/efi: Move uaccess en/disable out of efi_set_pgd() Ard Biesheuvel
2025-07-11 13:41   ` Will Deacon
2025-07-14  6:38     ` Ard Biesheuvel
2025-05-14 17:43 ` [RFC PATCH 7/7] arm64/efi: Call EFI runtime services without disabling preemption Ard Biesheuvel
2025-07-11 13:48   ` Peter Zijlstra
2025-07-14  2:20     ` Ard Biesheuvel
2025-07-14 10:55       ` Peter Zijlstra
2025-07-15  0:46         ` Ard Biesheuvel
2025-07-11 13:44 ` [RFC PATCH 0/7] arm64: Make EFI calls preemptible Will Deacon

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