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 A6019E6817A for ; Tue, 17 Feb 2026 12:26:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id: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-Owner; bh=tfKzSeau4sWZSt12SmP9c2jYzxSDL7+fSWgN7FTF05M=; b=ZGJSBJqLS1mc+8/EcAPi095lfc QTyDRRIepCpj7b2Mm5i+XJ7obzT8UR7nWg11WfDXvgZ4lkvGGB7VBoXPM4m7LC4QJ+I+y2SBfHX+K 188AFMLoJZkeB7ANCQfB6WYSqa2Wz2jkR/gOp06NRkrY/9tswBpIPer6Ktt/g2ejLhx6BZaSBBbKW KKdgBa+9taWavDfpqLO7/YrPJCUbJzSZH8fVNGagV+w7Dm0kgZcHM/JUkAo5sK9c7EvxYHKXZtJnh rxwIH84fuEfQQXeE01foGKPM5lwxWpOuVFKt/2l6jUxmnASuHUb05uipx1RRSBWOhgjMpcHY0BlEF c+USS+JQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vsK9Y-00000008ChN-35V5; Tue, 17 Feb 2026 12:26:08 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vsK9X-00000008Cgy-28MM for linux-arm-kernel@lists.infradead.org; Tue, 17 Feb 2026 12:26:07 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 987D860128; Tue, 17 Feb 2026 12:26:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7682BC4CEF7; Tue, 17 Feb 2026 12:26:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771331166; bh=2KlYMYJvT7Y1hTSO1LDecXwagv+AIm7sgfiCCrb0pYE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TI9AL0PJHNoLl0/+DUPyswIEazvwwB78CNj8mD4bRvCbR0MbGiEPMChYqzrw9BFC2 5TLTun3MnEffKHQz/v6Y3Uf3AhgS3QgFmZqCBkviX700Y1USxbbpxaApVINvRFISki eWmMw3sy+XqJodL07DZFztJ+Vaw4Od0grh+QCYs1klINpTnvkD0akl5GhsyNKJauR6 4xzBmH6flQGJQWI7BggQc1RNioqchViAsoJvWYSoP4rq9HwMCn3NSjoV0OmfSnsma+ SBKANRTyf3bamNkIPyBIKePAyZqjmYqsRNWeJf9sD/3bZeqpDmScj1vw74vSsVxumV eCycN4OD+yb8Q== Date: Tue, 17 Feb 2026 12:26:01 +0000 From: Will Deacon To: James Clark Cc: Marc Zyngier , kvmarm@lists.linux.dev, mark.rutland@arm.com, linux-arm-kernel@lists.infradead.org, Oliver Upton , Leo Yan , Suzuki K Poulose , Fuad Tabba Subject: Re: [PATCH] KVM: arm64: Disable TRBE Trace Buffer Unit when running in guest context Message-ID: References: <20260216130959.19317-1-will@kernel.org> <86a4x8bw38.wl-maz@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Feb 17, 2026 at 12:20:14PM +0000, James Clark wrote: > On 16/02/2026 5:32 pm, Will Deacon wrote: > > On Mon, Feb 16, 2026 at 02:29:31PM +0000, Marc Zyngier wrote: > > > And even then, I'm tempted to simply get rid of any sort of > > > guest-only tracing, given that TRBE is not capable of representing > > > exceptions that are synthesised by the host, making it the resulting > > > traces useless. > > > > I think that effectively means reverting the series merged from here: > > > > https://lore.kernel.org/all/20250106142446.628923-1-james.clark@linaro.org/ > > > > but then we still need to clear TRBLIMITR_EL1.E. > > > > Removing that series would actually have the effect of turning guest trace > on in nVHE for non-TRBE sinks. The reason for implementing the filtering was > to turn guest trace off because a user didn't want to see it. What I meant was, revert that series and then also ensure that both TRFCR and TRBLIMITR are always zero while running in the guest. Is that not sufficient? Will