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 7F210D3A67C for ; Tue, 29 Oct 2024 18:50:50 +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:Content-Transfer-Encoding: Content-Type: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=TRJR9R5IHSgGtl1A11bcLec6KY/DTqbAljozQGl2rew=; b=DV0XNqNXsYtXaeynVA+YYKcLxv CPHQCF6tVwbQeoqSzx8PZY/JIJxbpHRO+p/IYF5qF0E3V1KH6VkMDb+pm5hKAGCSoHZnAFqbd1UUJ AQBT6JbgqpdzZlhGWPs1Rw3GcaXn3cjK49AN/xXqsgF/XbQu5sTWTHfnxYXnChEKel1CjbngkkSyI KX2KnbZKjFjgDsfBegAGFCBoKt32x6OokGLrtplgjfb4wM7VY0dHF8f4yOLopfBDtIObCrJ8d2HAI bZJDeKDuL3MvBtyutfGffySOa0daxZO1R7kTAvRczNkjbtpbFHlJDkjn1QQqmNJrTnnW1OH0z2dwH 468APNEQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1t5rIe-0000000FZmR-2wqB; Tue, 29 Oct 2024 18:50:40 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1t5rFc-0000000FYMn-3fcL for linux-arm-kernel@lists.infradead.org; Tue, 29 Oct 2024 18:47:39 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id D25385C5521; Tue, 29 Oct 2024 18:46:46 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8B90FC4CECD; Tue, 29 Oct 2024 18:47:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1730227651; bh=S8+gRCQ82buuid7niivRW0sZNsV61zi3mxR5t/hggD0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Ly2eFgGIN5rXRS0uoyRdB4tj/P6vCWubBcamm2P4jnc/VzNl4fH9KHdRZa5/Sn2x/ AQaVD/rBsxaAkpSgL77uRuf8YCnkJRip5u+8Kc2//ku+AvD9P5VcVZO05MSKri9zrV gmdZv9HoPAzDdrAcAncmXQCRfpAa5yya5wn6cnco32NKllGIN7gdkTSbbiz2LQ/cV+ aaivwg1tayAFHQQ5eQW/TXPcQi//XtAYbRPqB8nqfmn66OC6THRCTC5+rGUrtS8pGL f2bLOyPOHd2VVb9AlQGEsv1Of/tP7ALvFYPbGGsxo2GbZCyup0oMOjqZ4YhnXORh1f 0h6YuRwo3U8/A== 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 1t5rFZ-0081Xu-Cc; Tue, 29 Oct 2024 18:47:29 +0000 Date: Tue, 29 Oct 2024 18:47:29 +0000 Message-ID: <865xpa3fwe.wl-maz@kernel.org> From: Marc Zyngier To: Raghavendra Rao Ananta Cc: Oliver Upton , linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, stable@vger.kernel.org, syzbot Subject: Re: [PATCH v2] KVM: arm64: Get rid of userspace_irqchip_in_use In-Reply-To: References: <20241028234533.942542-1-rananta@google.com> <868qu63mdo.wl-maz@kernel.org> 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/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: rananta@google.com, oliver.upton@linux.dev, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, stable@vger.kernel.org, syzkaller@googlegroups.com 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-20241029_114733_599876_AB5E8792 X-CRM114-Status: GOOD ( 18.88 ) 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, 29 Oct 2024 17:06:09 +0000, Raghavendra Rao Ananta wrote: >=20 > On Tue, Oct 29, 2024 at 9:27=E2=80=AFAM Marc Zyngier wro= te: > > > > On Mon, 28 Oct 2024 23:45:33 +0000, > > Raghavendra Rao Ananta wrote: > > > > > Did you have a chance to check whether this had any negative impact on > > actual workloads? Since the entry/exit code is a bit of a hot spot, > > I'd like to make sure we're not penalising the common case (I only > > wrote this patch while waiting in an airport, and didn't test it at > > all). > > > I ran the kvm selftests, kvm-unit-tests and booted a linux guest to > test the change and noticed no failures. > Any specific test you want to try out? My question is not about failures (I didn't expect any), but specifically about *performance*, and whether checking the flag without a static key can lead to any performance drop on the hot path. Can you please run an exit-heavy workload (such as hackbench, for example), and report any significant delta you could measure? Thanks, M. --=20 Without deviation from the norm, progress is not possible.