From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 306802BEC2D; Mon, 15 Dec 2025 09:33:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765791231; cv=none; b=L7LDWWIi7F7fPqUJo9gVxBBRZSKvijgQhyLoZlm1P94LJPLvGYhbZkM0hLM8Ldukmv65qzUlu6biY7rQQX8aCuXnjPT0u6AdbQNiabimgCb/X6tLxTpJyHKWRN5YaE6q9X4PC5Q4AAsy5/N7jpTlwcDPbCIj8xFGpvzHNVO5Htg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765791231; c=relaxed/simple; bh=SeF9YpW8ZZv1PqRsseJuqiCynezLQg+Dpkn6Gx/DWrM=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=c0K33baWTycM8/WUlIeAWyexrdtgD5imPzCsVNZ7HBzAober7B7Lg7BDh2S/paQ/Iwzm/UP6rVbhlEywYBDjF8rjHmPyYVgLnq5OzJd8aESJ+wLAST8Euff8Km/AyCSMysfWAYi6iSaawvYSWNgYAItjGe7rl+jZ7Je9cxaYM6M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Xt1v9Zy6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Xt1v9Zy6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B2690C4CEF5; Mon, 15 Dec 2025 09:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765791230; bh=SeF9YpW8ZZv1PqRsseJuqiCynezLQg+Dpkn6Gx/DWrM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Xt1v9Zy6vJn3XucSIhPiWS5DgEBL8MeL8S3hjUOZ92Pz+AF2MsIKRPE4X+WE23PXB 8vZa/Foh1wS2BLniSCP/VRE6zIjzaao6VIZtWIaWvO8QpDz6XATn/HMt4pEPx7kJ6D CAr4/XhcmkEIMyuTaoSdxBgVfhKphIvDaO6xyHazeILXiuNsz2ZpcPkgDbmjI2sahs wtW/iYCyHIyVMkgcJBGgdA0Gx7tAHlClPmM5dyf0Vr0ohcy4zDqsu+6kuAH1rttPPM bJanP79mJIJ/YOa+hi6bvpvXE1/UuTjmxYUMGi6i+JICrwdMa/RVMXjoKFUYP3ukLo iW3VfwHc28bPw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vV4xg-0000000Ciix-00EC; Mon, 15 Dec 2025 09:33:48 +0000 Date: Mon, 15 Dec 2025 09:33:47 +0000 Message-ID: <86ms3knl6s.wl-maz@kernel.org> From: Marc Zyngier To: Yeoreum Yun Cc: catalin.marinas@arm.com, will@kernel.org, broonie@kernel.org, oliver.upton@linux.dev, miko.lenczewski@arm.com, kevin.brodsky@arm.com, ardb@kernel.org, suzuki.poulose@arm.com, lpieralisi@kernel.org, yangyicong@hisilicon.com, scott@os.amperecomputing.com, joey.gouly@arm.com, yuzenghui@huawei.com, pbonzini@redhat.com, shuah@kernel.org, mark.rutland@arm.com, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH v11 RESEND 9/9] arm64: armv8_deprecated: apply FEAT_LSUI for swpX emulation. In-Reply-To: <20251214112248.901769-10-yeoreum.yun@arm.com> References: <20251214112248.901769-1-yeoreum.yun@arm.com> <20251214112248.901769-10-yeoreum.yun@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: yeoreum.yun@arm.com, catalin.marinas@arm.com, will@kernel.org, broonie@kernel.org, oliver.upton@linux.dev, miko.lenczewski@arm.com, kevin.brodsky@arm.com, ardb@kernel.org, suzuki.poulose@arm.com, lpieralisi@kernel.org, yangyicong@hisilicon.com, scott@os.amperecomputing.com, joey.gouly@arm.com, yuzenghui@huawei.com, pbonzini@redhat.com, shuah@kernel.org, mark.rutland@arm.com, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Sun, 14 Dec 2025 11:22:48 +0000, Yeoreum Yun wrote: > > Apply the FEAT_LSUI instruction to emulate the deprecated swpX > instruction, so that toggling of the PSTATE.PAN bit can be removed when > LSUI-related instructions are used. > > Signed-off-by: Yeoreum Yun It really begs the question: what are the odds of ever seeing a CPU that implements both LSUI and AArch32? This seems extremely unlikely to me. M. -- Without deviation from the norm, progress is not possible.