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=1794328581; b=qDJgL+kzidSmFA+Id9xRFpfBjH0HLE02aaXNIxph81MqgGckrnYtv9OdbiI0rzri882M x9FQ5kcmBCPK5I3bn1Yl8VG/x+Kf6IaBxLuPoXe+RMF/9Z9HdBkuW4g8UFYp4eyrnrpZq wDa/MTtNraL/S9VU0weF0K0/kWa4qWfWDPqupcKkZNhDlGmMGlaQUUeC8R7drkS489ss6 j/uslFkD65KUgit1Mo5m2+qL0QMI9rP0lrggWxDlZ86uNIIv8UYIDu9MyFmwOtI87be5Z e7TRRkrtawA7rL8rV7whS5leMNQafo/UsPPg88mdB9UFo8VPhWN5sZ0F9zPkkNWNUEA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794328581; 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=/2IklnXQ8VDOasmnc4s8LlsX94sJzF0TyhpWpFGrd40=; b=0UUQVp8BwozPr7xxqj55/2Kje0Xd71LZgfCGbz0tAi3PAO+bqb/SXJhaMPPRjswrkiMP muoSheJHJ/XxaOdvHhsOSWSF3VVR6cuU4GJcLtpALs+pWm7YkbRwodupy0Bo6Hy+FVcVL v4DdA2aEOkv95tZg2pu2lUdqKEOSEt8bMtjbzQHTWJuTcrkJ4Ko6xf/QpeqmAZZX3hecz KvFpoGnJiYOzGOF6YSfOBc7nQAgaN6N1858t/BLRUOZin1anJR8d8OLbBiGgT5mC0cQAJ eZ1Xu7n3JVUCZFzm2LKBQQqJuwFyKH1pNvaCQRnyIkR0RQ4QggpRHloBqHIS6jlBCgQ== 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=sYozmqnT; 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 462EF606A20D; Tue, 10 Nov 2026 16:36:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 462EF606A20D 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, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=sYozmqnT 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 3924B1477; Tue, 10 Nov 2026 08:36:16 -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 234893F85F; Tue, 10 Nov 2026 08:36:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1794328579; bh=W93zuHvv0B3GjuQYbnfR2B0hYUYTD/1HhAutAvOyHc8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=sYozmqnTmmj1HDyt+LmelivUTXfURzy4ZuotqpQSAnyER6/dyDFtKIFkVkn0SmpO+ O+RU5XZyaIzhycu65Pmw23utreNYCUqv9PnuZP1DrGLbr5D7k6uP7oHKi7dXqKJdYN CbmlR/v3UEIQ3c8AHIpFUW0pKrLveLcUhkh7pNdA= Date: Tue, 10 Nov 2026 16:36:12 +0000 From: Yeoreum Yun To: Mark Brown Cc: Kevin Brodsky , 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 , Yeoreum Yun , 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> 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: On Tue, Nov 10, 2026 at 03:53:30PM +0000, Mark Brown wrote: > On Mon, Nov 09, 2026 at 03:58:32PM +0000, Kevin Brodsky wrote: > > From: Yeoreum Yun > > > > The POR_EL1 register is reset to an unknown value after cpu_suspend(). > > Since POR_EL1 always holds POR_EL1_INIT when entering cpu_suspend(), > > initialize POR_EL1 with POR_EL1_INIT before cpu_do_resume(). > > > +#ifdef CONFIG_ARM64_POE > > +alternative_if_not ARM64_HAS_S1POE > > + b .Lskip_por_set > > +alternative_else_nop_endif > > + mov_q x2, POR_EL1_INIT > > + msr_s SYS_POR_EL1, x2 > > + /* isb can be skipped since cpu_do_resume() will do it. */ > > +.Lskip_por_set: > > +#endif /* CONFIG_ARM64_POE */ > > cpu_do_resume() will update TCR2_EL1 to enable POE again, a sufficiently > unhelpful implementation could potentially decide to do that before this > POR_EL1 value takes effect AFAICT given that there's no barriers. Thanks. seems required to isb() after initialising SYS_POR_EL1. -- Sincerely, Yeoreum Yun