From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794489249; b=ttdjlAO9g8/mUTVngrUSbisfmNT7T/6TqAXCi1yaC9CUqViudJlRldkuOWLcKZRJ4PF8 Aqbj7jR28Pv0+Ww+MNj9Az9A0YWZ8FlW1RrHo2yLbhwr87YVmCzymCiBySWiwvV30GQMZ fgi1lr0Bl4F2ENG4Uxdos2w/YB3eqH1Rso/MZIWo9r4YHPgaK0XggSOD9LUiIARS/NHYf jcrvuqjehHalzGUk4Op1O4mQQ348tImKEzYeuRyN96p4NxWVlYtbmAfOlGiPd2cink8Yb Sjd8PB8N1t/T06M0pL2086tLMKm5YcI+6Ic6QDJjDYQyTe5K7CmSuY8971qzqeyOrSA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794489249; h=DMARC-Filter:Received:Received:DKIM-Signature:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=yRd8+Huvlp5plhQTndzEeeQ6oPa/Jct92yGvLHnpzEw=; b=UoCgGdUUMQks6/Md8GANft3LpzVuFBPGjLt92iVqSrpo0updk7aMCrzEzkUoZFdQZIV6 /5T5S6Iv/KxBN8sryu/IV0LR/MuaF3q6fcIADd/Q4ut7ZmJO8Ae8fk7+QaLD1S3UZaN9i vArum2IE9GgFlVVbEYV730YX27udHIJyr9orndUq9Tgt5eWc9DaokMEtD6wemp8C4nLUL bM/urTOzf04xqPt8NXsnShvRiiULHdkyMuKd43F3U0tD6eidYvDiVUOoJbf1B7ABJf1JI +n86k7RNkL1CWksjlglGNBvbeeRZuFSac3iZ4hU1aS+5eOawbdP+nYNohwF4Kp70fQg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=Ir+GhsOF; arc=none smtp.remote-ip=217.140.110.172 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id F280A606A330; Thu, 12 Nov 2026 13:14:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org F280A606A330 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=Ir+GhsOF Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 5389C1576; Thu, 12 Nov 2026 05:14:05 -0800 (PST) Received: from e129823.arm.com (e129823.arm.com [10.2.213.3]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 215A13F632; Thu, 12 Nov 2026 05:14:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1794489248; bh=w1bnY+Ps4zITYTRUimdbVrN0cNHgFPf1y5ifSbYb950=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ir+GhsOFl4eXFwGT7DY570KXtbzdF31B+5y++WKx8y5Mt8D9PCavJtunWAPhq11FQ 3y9F+FQeN7oJYgE6McH1/9bBfmGxPdH3wzJzX2m8BupRfTjtvOMcJ34FftvP/WD6se sCtXi4bJ4nt0qiwC4fHQYnZSriQiUhYjZrdlfgEs= Date: Thu, 12 Nov 2026 13:14:01 +0000 From: Yeoreum Yun To: Mark Brown Cc: Kevin Brodsky , Yeoreum Yun , linux-hardening@vger.kernel.org, Andrew Morton , Ard Biesheuvel , Andy Lutomirski , Catalin Marinas , Dave Hansen , "David Hildenbrand (Arm)" , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linu Cherian , Linus Walleij , Marc Zyngier , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , =?iso-8859-1?Q?Pierre-Cl=E9ment?= Tosi , Quentin Perret , Rick Edgecombe , Ryan Roberts , Vlastimil Babka , Will Deacon , Yang Shi , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org, Ira Weiny , Lorenzo Stoakes , Thomas Gleixner Subject: Re: [PATCH RFC v10 07/22] arm64: Initialize POR_EL1 register on cpu_resume() Message-ID: References: <20261109-kpkeys-v10-0-aa6c4d9603bc@arm.com> <20261109-kpkeys-v10-7-aa6c4d9603bc@arm.com> <7b92f7c8-1543-447e-8ef3-aba608141699@arm.com> <6808f3a6-1c12-4cb2-a109-30704d812490@sirena.org.uk> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6808f3a6-1c12-4cb2-a109-30704d812490@sirena.org.uk> On Thu, Nov 12, 2026 at 01:02:16PM +0000, Mark Brown wrote: > On Thu, Nov 12, 2026 at 01:38:13PM +0100, Kevin Brodsky wrote: > > On 10/11/2026 17:36, Yeoreum Yun wrote: > > > > Thanks. seems required to isb() after initialising SYS_POR_EL1. > > > Agreed (as Sashiko reported as well). Presumably that means we also need > > an ISB after writing to POR_EL1 in cpu_enable_poe(), as that's basically > > the same situation. > > Possibly just have one before writing TCR2_EL1 rather than for each of > the indvididual features, that's harder to mess up? I'm not sure that's necessarily better, as we'd end up executing an isb() even when POE or other features aren't enabled. Wouldn't it be better to execute an isb() only when needed? -- Sincerely, Yeoreum Yun