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 86C863D90 for ; Thu, 21 Sep 2023 07:39:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AC5A9C43215; Thu, 21 Sep 2023 07:39:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1695281995; bh=6pNyXq2RZMPL5x7hcfLT9+oov3jusYl/Qty+7oyN1/w=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=KfBes/RVId2ghmYa67l/8slvtw9rB1dtRAdAD/szL300HhaDxs5UARdJrD6er3xZP dkTwTHqXNwaaFNxRUVSdpdbCil+X/WH633GYU/Gx95fX4hDm7znzVwfSvabJvLoJ5E 5m4YK2GPqrMSKiAq5fKzHzNPByYZVlYcQjhBu+gB1ioSePg1nmokARPL34wQYrMitf aCJ8d9a/TTjt1HTX0vGQzGdfcUpVWXIKki/EUzVAf27sgxQNEc/Rt5tG+uBqvSZwSQ ProvQ5Eyxs9T3Ax+1c2ZHV9o0uer1gewLdUhC0zNie/ZU9nZd/HW+cbtZm/MBPM0X8 qC62SUeJWmbFw== Received: from 82-132-232-12.dab.02.net ([82.132.232.12] helo=wait-a-minute.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 1qjEHw-00Es5g-NK; Thu, 21 Sep 2023 08:39:53 +0100 Date: Thu, 21 Sep 2023 08:39:45 +0100 Message-ID: <875y443rge.wl-maz@kernel.org> From: Marc Zyngier To: Oliver Upton Cc: kvmarm@lists.linux.dev, kvm@vger.kernel.org, James Morse , Suzuki K Poulose , Zenghui Yu , Will Deacon , Catalin Marinas , linux-arm-kernel@lists.infradead.org, Gavin Shan Subject: Re: [PATCH 0/2] KVM: arm64: Address soft lockups due to I-cache CMOs In-Reply-To: <20230920080133.944717-1-oliver.upton@linux.dev> References: <20230920080133.944717-1-oliver.upton@linux.dev> 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/28.2 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 82.132.232.12 X-SA-Exim-Rcpt-To: oliver.upton@linux.dev, kvmarm@lists.linux.dev, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org, catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, gshan@redhat.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Wed, 20 Sep 2023 09:01:31 +0100, Oliver Upton wrote: > > Small series to address the soft lockups that Gavin hits when running > KVM guests w/ hugepages on an Ampere Altra Max machine. While I > absolutely loathe "fixing" the issue of slow I-cache CMOs in this way, > I can't really think of an alternative. I don't think there is any, unfortunately. I don't think this change is inherently bad (we should have added something like this a long while ago), but it scares me that these systems can apparently be DoS'd from userspace or a guest... Anyway: Reviewed-by: Marc Zyngier M. -- Without deviation from the norm, progress is not possible.