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 E571BC4345F for ; Wed, 1 May 2024 19:51:42 +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=6+K7Z3k6+2/MnkLb0P7ewdG/lIcPjvKWC1kEKSROEnE=; b=X2jlkhRK8gj+hM FJvqUORzQBfgQaGEBn565mkUcSQWPMqPa6BBFkeMdwPWcXsrgXP3ZL0FWl5Jn7OlUaO41x+NxJ+WN 3w1itsDyjXTzZ9YslEwsKnW8ecN1ltbfZ8oJ7hipbAtn04BGo1VlQz/Tlv1PBRLWH0ZNuzb7KmARB dLhFfLO0UOR3KNjd/V0klrJTZYEK1RQXfNoHtDxs9l/ls2LqbhtBiuGlQxbSUBE9H85m91z3Kg71L X5eXu1DT+4CclGamb/bye+lRytjl07BKqnGk4zSntp8JDk6gsO5vR0xtEO/veuPWCOYmxxuOs+14V VHMkIwf3xSS4hm7mdiQg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1s2FzI-0000000AZTa-26ib; Wed, 01 May 2024 19:51:32 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1s2FzF-0000000AZSI-3IBU for linux-arm-kernel@lists.infradead.org; Wed, 01 May 2024 19:51:31 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=0A31sCIBZJeiwuMP4GxlbOVkmUB2QfLVfijRKGWXcFU=; b=ceA7PnxkXiACKUL8mtep4lA+y5 S2bEbuXDW4kNrbNUgRcyDoamwX22ZQrjZ+M6xmzTd5bEl21SJvFN6I8JkVCRIzDyQKecj5dFi2vuy woWHCO98NxgJfbuMkl6CkcpTQSngVCHQ2AEjLsbNSb3LKj3VahBPiZ1myDl+FE9/R9KGHUbgHRbCA 9XlxqtFgh+EAXTiab0w8dZ6VRLXimhlpkPhFA8uJ4I63agFziQ8QgBzrR+rtN/eraI0P9OZXZMt36 oEtaEn0aE8HCkplduneOK49QxfIv+tFgQO919I6+Z++xN9fWQAYLzSvAwSS8bqU3lfrBhynzpOnn6 kjeDnwTQ==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:38288) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1s2Fz3-0006Zk-0G; Wed, 01 May 2024 20:51:17 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.94.2) (envelope-from ) id 1s2Fz1-0002yu-OR; Wed, 01 May 2024 20:51:15 +0100 Date: Wed, 1 May 2024 20:51:15 +0100 From: "Russell King (Oracle)" To: Oliver Upton Cc: Marc Zyngier , Catalin Marinas , Will Deacon , James Morse , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev Subject: Re: [PATCH RFC] KVM: arm64: allow ID_MMFR4_EL1 to be writable Message-ID: References: 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-20240501_125129_846199_65294FE5 X-CRM114-Status: GOOD ( 26.41 ) 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, May 01, 2024 at 06:59:17PM +0000, Oliver Upton wrote: > On Wed, May 01, 2024 at 07:08:05PM +0100, Russell King (Oracle) wrote: > > On Wed, May 01, 2024 at 05:57:20PM +0000, Oliver Upton wrote: > > > Hi Russell, > > > > > > On Wed, May 01, 2024 at 06:06:51PM +0100, Russell King (Oracle) wrote: > > > > Between 5.4 and 5.15, the guests view of HPDS, CnP, XNX and AC2 > > > > changed their value on the same Neoverse N1 r3p1 hardware which makes > > > > migrating between these kernels on the host problematical. > > > > > > It'd be helpful to expand a bit more on how these fields changed, better > > > yet if we can blame it back to a commit. I'm guessing the only direction > > > of migration you care about is old -> new then? > > > > Yes. For MMFR4_EL1, we see 0 with our 5.4 based kernel, and 0x21110 > > with our 5.15 kernel. I've been looking at tracking down which commit > > is responsible but I've come up with nothing that fits. > > > > The only change I can see is the FTR definition for MMFR4, but this > > always included 4:7 (AC2) which changed 0 -> 1. So... no idea what > > commit caused the change. > > > > There are a load of other registers that we need sorting, but this > > is just a test forray into attempting to solve this. > > Got it, let me see if I can find it then. Do share that list of > problematic registers when you have it, hopefully this isn't the tip of > the iceberg... There unfortunately is an iceberg, but hopefully it isn't big enough to sink a ship! Besides ID_MMFR4_EL1, here are the other differences we've identified. Note that these are Oracle's UEK kernels, so based on stable kernel branches. Register Field 5.4.x 5.15.x ID_PFR0_EL1 CSV2 0 1 ID_ISAR6_EL1 DP 0 1 ID_PFR2_EL1 SSBS 0 1 CSV3 0 1 ID_AA64DFR0_EL1 PMSVer 1 0 DebugVer 8 6 ID_AA64MMFR1_EL1 XNX 0 1 ID_AA64MMFR2_EL1 EVT 0 1 KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2 0x12 0 I think some of these differences are due to Marc's removal of the WA2 code in commit 29e8910a566a ("KVM: arm64: Simplify handling of ARCH_WORKAROUND_2"). The WA2 register for example has changed from avail/enabled to not_avail. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel