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 6B77AC54E58 for ; Mon, 18 Mar 2024 15:25:05 +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:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=XV9ia5rEBLz5X4o9wcxBldWAk26K5gQckR1nuSnkYOg=; b=UGxHXp4fCZnNfy ZbK8xyQSRmjXQpLfRbYFsznNQiD1+n4UBYtyCO6/93cxETi+192KlOdrpguU7gjpT8aFZxmk/dBZZ 0/D94JJlFy47nP5roD0wKzXVO5GUxx2uYQYdqvLnUM3yPNYoXpm96zZ3POWRKfoFZR8EEmzZubcXl wPItaMt8KHe8jAjg0uKYoXxsVD6cklmHC+OoRglZHSGS38C+W8voPspTzBVe2Ir1cdElax7UXwFrr BEM/9Sjtsm7eN6pkgkqT3Dz7qfUtT7XiERE4+stfgktUMgWDDC7yxFiKHVOisVryM4DRuOwcUiS7F v/WCrcZK9rrBsKvO4Vpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmEr7-000000091Pb-1OW1; Mon, 18 Mar 2024 15:24:53 +0000 Received: from sin.source.kernel.org ([145.40.73.55]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmEr3-000000091P7-3vWi for linux-arm-kernel@lists.infradead.org; Mon, 18 Mar 2024 15:24:51 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sin.source.kernel.org (Postfix) with ESMTP id 4D2EBCE0ABA; Mon, 18 Mar 2024 15:24:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8D5C0C433C7; Mon, 18 Mar 2024 15:24:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710775487; bh=S8LYBr1flNlq1r7kyHhu22A4oDaV3dPNEZmCdc0vdZ0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=W6uByha76p5Vs8BjyyxfzTYNj6aTsPeEOt2q3RejwRNCyK12fnY9bCuBxgNRlDmk+ 9pMi4s8FvxQmuE2F/eoPD3FtyBTEbk0NaJ4DL2b17SIHW6/RwpSOfcjzsab9DElOnM 0D9ffRLOtsBwhp8S00KbGY1Jdv9ucZhC+OGMTizb1bdBuxcOwGk2LuIeroigYU6kLG R9F7w+8EMdTjZxOTGHBm2SQjMA9CK6X0nI5NeSS5wdV8XwJZ+NlcaPGD1uwIvcd3ZM Zybz8rYxJYTGcEbm8ZLqw9v3TDA1d76b+1lJfjunfYPHm+gdcpJg8F5py0GF5FUQyw Q2NCl4+GI2wAw== 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 4.95) (envelope-from ) id 1rmEqz-00DJ0A-J9; Mon, 18 Mar 2024 15:24:45 +0000 Date: Mon, 18 Mar 2024 15:24:44 +0000 Message-ID: <86y1afzhoj.wl-maz@kernel.org> From: Marc Zyngier To: Sebastian Ott Cc: linux-arm-kernel@lists.infradead.org, Oliver Upton Subject: Re: [RFC] [PATCH 0/4] KVM: arm64: emulation for CTR_EL0 In-Reply-To: <20240318111636.10613-1-sebott@redhat.com> References: <20240318111636.10613-1-sebott@redhat.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/29.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: sebott@redhat.com, linux-arm-kernel@lists.infradead.org, oliver.upton@linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240318_082450_177203_4FCE9775 X-CRM114-Status: GOOD ( 16.11 ) 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 Mon, 18 Mar 2024 11:16:32 +0000, Sebastian Ott wrote: > > Hej folks, > > I'm looking into supporting migration between 2 Ampere Altra (Max) > machines (using Neoverse-N1). They are almost identical regarding > their feature id register state except for CTR_EL0.DIC which is set > on one machine but not the other. > > For a complete picture it's worth noting that the machine with > CTR_EL0.DIC = 1 also suffers from erratum 1542419 meaning for > userspace we trap the access and fake DIC=0. A KVM guest still sees > the original host value for that register (I assume that this is > intentional so that a guest OS can apply its own workaround to the > erratum). Indeed. The intention is that the EL1 guest will hide DIC for EL0, while EL3 will trap IC instructions from EL0 and replace them with a TLBI. That's of course assuming that the machine has received an updated firmware, something that cannot be probed AFAICT. M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel