From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 0AA6A2F56; Tue, 29 Oct 2024 18:47:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730227652; cv=none; b=uuxpjoZk6D1o6CMR1b4KJSCI0mvWfkpui9EGXERD8m0SD+7jLk2E0XIdINGQmbKVJjpOp1kiyiup/LuyyIETzv3nqLa2GyGcmjGa7eafO8N0fvb5oV+FVPlk1dkOX4GIjg8EKxYGDINyFrAMQiBOuZ9/6uK76BzHq/AwjNw1vnQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730227652; c=relaxed/simple; bh=S8+gRCQ82buuid7niivRW0sZNsV61zi3mxR5t/hggD0=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=jKzoE751oiuUFyNKl5s2ZKqWg7iXyXbFuf61Q+9E/iADAFIN3LS5PRjZS7QZV3EeaeCcl+KmllCvyOgqOMU1utaxNKXxQymu9/N7w+cEhjV7lDB9pLmS122zw3f441/K+xYCeiYmScGa174RdK5t/bIJ+2VFe5k9BTQ7QKv4fDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ly2eFgGI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ly2eFgGI" 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) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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.