From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 08EEE17BD3 for ; Fri, 20 Dec 2024 15:01:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734706878; cv=none; b=bbPnHklgB9oFkFsHL+puhmcXK9OlkdYjzqLqFpnj8beJtYNAcJ2RTiXLklk1fPDIdv1RpesWHnxbHYRzhLpKlWcvSQr47b8KrLFKttt0BBXUQYHmhVP2F8jEbkLfF3An0w2yIXdr7RGlMcm08LVhIiNIWF2/a3IuWDyxnw6MIaw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734706878; c=relaxed/simple; bh=FU8u7FgteP60R1LVsxBg0Y2jrMf1zurXaeJFrIqaxrc=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=KfI5l0yR0PZKvLumeTTlzKGaB+oCjQCAtwA8lKac+tEAWCYBUKniIoBY8sREvhD08KCl12eoJZwhtOgzcJwILzXQvaEAqNWZeoLhy84dNC0Af38J1hAD8eSSyMDeUcJi35LbH0zMhmndoRLT+KLUy/RmZJARrFOOeL8tGcmlXuI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=aq7TqP1a; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aq7TqP1a" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1734706876; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=nZvwncwJOuHramMroFGr8eBsUbQp9V+RXkC2LSaW6Lg=; b=aq7TqP1aBwMvpgm6udG7x+SqYvB08OKQdTT36tf6oqtwGKXPjCtCNUosU99RiqUQxkfCGG bcUQ3HtBsmbE92O2E5p43Q7JpuyzIh96SaSsD2Ba/5kU61RSeZedFBQw6V6oAgaCqutK+e TPl5aSDbgtyl8ex/W1THToFyMyeGkzY= Received: from mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-619-JQCwutYbOvi5j9rBr_W_nQ-1; Fri, 20 Dec 2024 10:01:11 -0500 X-MC-Unique: JQCwutYbOvi5j9rBr_W_nQ-1 X-Mimecast-MFC-AGG-ID: JQCwutYbOvi5j9rBr_W_nQ Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 292DD195605B; Fri, 20 Dec 2024 15:01:03 +0000 (UTC) Received: from localhost (dhcp-192-244.str.redhat.com [10.33.192.244]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3008F1956053; Fri, 20 Dec 2024 15:00:59 +0000 (UTC) From: Cornelia Huck To: Marc Zyngier , Oliver Upton Cc: Shameer Kolothum , kvmarm@lists.linux.dev, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, eric.auger@redhat.com, sebott@redhat.com, yuzenghui@huawei.com, wangzhou1@hisilicon.com, jiangkunkun@huawei.com, jonathan.cameron@huawei.com, anthony.jebson@huawei.com, linux-arm-kernel@lists.infradead.org, linuxarm@huawei.com Subject: Re: [PATCH v4 3/3] arm64: paravirt: Enable errata based on implementation CPUs In-Reply-To: <86v7veppsj.wl-maz@kernel.org> Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Michael O'Neill, Amy Ross" References: <20241218105345.73472-1-shameerali.kolothum.thodi@huawei.com> <20241218105345.73472-4-shameerali.kolothum.thodi@huawei.com> <86bjx8q995.wl-maz@kernel.org> <86v7veppsj.wl-maz@kernel.org> User-Agent: Notmuch/0.38.3 (https://notmuchmail.org) Date: Fri, 20 Dec 2024 16:00:57 +0100 Message-ID: <87ikrebdqu.fsf@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 6LyvB_b7u5ZuUYY2BepSESaR96g2_bVq1DaUlhLgync_1734706865 X-Mimecast-Originator: redhat.com Content-Type: text/plain On Fri, Dec 20 2024, Marc Zyngier wrote: > On Thu, 19 Dec 2024 17:40:55 +0000, > Oliver Upton wrote: >> >> > Independent of this, I wonder what we should output in sysfs >> > (/sys/devices/system/cpu/cpu*/regs/identification/*). >> >> It's a bit crap, but maybe implementation index 0 gets reported through >> the 'main' midr/revidr files, otherwise have a directory per >> implementation index of midr/revidr. > > Having slept on that one, I'm starting to think that we should keep > the status-quo of reporting what the kernel snapshot at boot time. > There is no good reason to force the VMM to report the potential > implementations in any specific order. > > The "alternative-implementations" is interesting, but we don't keep it > per-CPU, so I don't think it fits the current scheme. But maybe > something in /sys/devices/system/cpu, outside of the cpu* hierarchy? I agree that this should be reported outside of the cpu* hierarchy, maybe smth like /sys/devices/system/cpu/alternatives/ identification/ regs0/ aidr_el1 midr_el1 revidr_el1 regs1/ aidr_el1 midr_el1 revidr_el1 (with no guarantee as to _which_ triplet will show up under regs) Also depends on the intended consumers, I guess. > > Either way, this isn't something we should worry too much right now. I agree as well.