From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 003E0C77B73 for ; Thu, 20 Apr 2023 09:52:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=oSqjcbfPmXmwmzy8xProiatQdQ/6Z7aTxqG0UTagxQg=; b=ggeTS5UqDAavTZ sYfdGwnNE678gZmxkvLDLcdlWFg1T74q3FfEkBgBSkykdNKw7FhqH6wc9GKVQC2CET+4Lvqn3hvX2 1fHmsbqSXQjr276i8gFhHiAFOXPRS2+6na6MQd1XeMuJdYSq7fDPbDkUYaeJJVPjSYjGi2nxqnfYy lujd7f+3ImY10X7raq+Or9DUbiUWvy9fjTTeSG2f6QjQY8Pj310lRydqBKYDtg01OyZ49YmC1Sb8k JofH7TtDcGswW3jYxzxDtEvbTWH12ChnG3O+w7KeRNEd1x/t4u3ol+acseFSL6dS2ejryj/bQG1Sa SwX8d7vKWpCd9kt/y0KQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ppQwu-007bJC-2G; Thu, 20 Apr 2023 09:51:32 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1ppQwr-007bIX-3C for linux-arm-kernel@lists.infradead.org; Thu, 20 Apr 2023 09:51:31 +0000 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 E9C701480; Thu, 20 Apr 2023 02:52:09 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E7A8E3F587; Thu, 20 Apr 2023 02:51:24 -0700 (PDT) Date: Thu, 20 Apr 2023 10:51:22 +0100 From: Sudeep Holla To: Robin Murphy Cc: Ayan Kumar Halder , mark.rutland@arm.com, lpieralisi@kernel.org, linux-arm-kernel@lists.infradead.org, Sudeep Holla , linux-kernel@vger.kernel.org, Vladimir Murzin , Stefano Stabellini Subject: Re: SMP enablement on Cortex-R52 (using PSCI ?) Message-ID: <20230420095122.chw527nozzwkopnx@bogus> References: <1cb7d428-c047-1485-e39d-465806f6ef0b@amd.com> <20230419084756.3gypfyuuezjj7tyd@bogus> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230420_025130_092180_BEABEA1B X-CRM114-Status: GOOD ( 14.87 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Apr 19, 2023 at 06:50:26PM +0100, Robin Murphy wrote: > On 19/04/2023 9:47 am, Sudeep Holla wrote: > > > > I will check with the authors if EL3 is a must for PSCI implementation, but > > IMO it must not be though every aspects described in the spec may not apply > > when used across EL2/EL1 boundaries especially when EL3 is not implemented > > in the hardware. > > Xen could provide PSCI to EL1 guests using the HVC conduit. However if EL2 > is the highest implemented EL, then Xen is the most privileged software in > the system - it would have to own the EL2 exception vectors, and it would > have to own the low-level CPU bringup code. At that point it just wouldn't > make much sense to HVC *itself* via the PSCI protocol when it could simply > call the function directly. > Agreed, I was focussing to much just on EL2/EL1. I don't know details on how power management responsibilities are split between Dom0 and hypervisor, but I am more interested in understanding how cpuidle/suspend would be structured with the direct function calls. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel