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 982A3CFA765 for ; Fri, 21 Nov 2025 09:54:53 +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-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID: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=p+szjHYwqS2Mr65bGjesKFDKj1wE6uXd8EXsGbGaDwM=; b=PmG9XpAQz91NA9/RXPZST6XxTf ew3CV240k7h6vUd9tK55GH96aj+QRx/jeYO2LbUPsM2EODZIx7VdF3J5Z5jIBFbZiDbvlbGAwL99s 1JVLVk7yjOFAVTvTj50bglkh4StSkxzRbeuZnQpAvFe7gMquG5bqNyypB21XsGfA3lHIgoVFrKY5T LymEb9dUXJWr7kIdWUa9XMTzSpeZYaO0C7KOBVfgikqeN2WocnXE0mJYe7rZTQPE+46Dl2h5d9UHr vNKW9oSFcQ4rXM8ZC/JSVvGFNbmg/gJmEdHcpHWVSMoHvwYAtCiQxV3MSQRxaHMDReX4i+ZMWAoaA I50lc1RA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vMNqp-00000008B16-1rMY; Fri, 21 Nov 2025 09:54:47 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vMNqn-00000008B0j-0qbh for linux-arm-kernel@lists.infradead.org; Fri, 21 Nov 2025 09:54:46 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 8F2FB42ABF; Fri, 21 Nov 2025 09:54:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67A69C16AAE; Fri, 21 Nov 2025 09:54:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1763718884; bh=ckVGtchhklPTh0H5XGrkBBtZKAvAc7k3gSAzJOeSpQs=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=cvAIznXbFms3ytp6HoL1PnFgWBzLDmgLo/T51jbEUr3jehiNEqJt/vdlrQR4LwuwO MBHnNHDT3SqJ55yibghKZZR2GCJIRGmPLQn/F7Gqq/AXRkcGfdEJHXuC5Uadr7eaSc C1r8aKoEBcLJnTrWIuHzJTY27sqe2FZUxJ+4fzKo9e8R03aioniGyyv0oP+S34uAN2 CTZUEvn8S843psmfy3frwRglXjJjIXmHIur9QCfSVztmkGBFfkCqhMo9T7RnroqV1m GHXuCqkGYj9+TDpzIuxcjy4Pdsh37gefspsv61zqWjIDOxBR3CsEqVbej9AuysyM2a +OjJwp2hEUjqw== 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 4.98.2) (envelope-from ) id 1vMNqk-00000007BJ0-05Ov; Fri, 21 Nov 2025 09:54:42 +0000 Date: Fri, 21 Nov 2025 09:54:41 +0000 Message-ID: <86zf8fr9r2.wl-maz@kernel.org> From: Marc Zyngier To: Tian Zheng Cc: , , , , , , , , , , , , , , , , , Subject: Re: [PATCH v2 0/5] Support the FEAT_HDBSS introduced in Armv9.5 In-Reply-To: <20251121092342.3393318-1-zhengtian10@huawei.com> References: <20251121092342.3393318-1-zhengtian10@huawei.com> 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/30.1 (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=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: zhengtian10@huawei.com, oliver.upton@linux.dev, catalin.marinas@arm.com, corbet@lwn.net, pbonzini@redhat.com, will@kernel.org, linux-kernel@vger.kernel.org, yuzenghui@huawei.com, wangzhou1@hisilicon.com, yezhenyu2@huawei.com, xiexiangyou@huawei.com, zhengchuan@huawei.com, linuxarm@huawei.com, joey.gouly@arm.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, suzuki.poulose@arm.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-20251121_015445_284975_12BCFBF5 X-CRM114-Status: GOOD ( 17.78 ) 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 Fri, 21 Nov 2025 09:23:37 +0000, Tian Zheng wrote: > > This series of patches add support to the Hardware Dirty state tracking > Structure(HDBSS) feature, which is introduced by the ARM architecture > in the DDI0601(ID121123) version. > > The HDBSS feature is an extension to the architecture that enhances > tracking translation table descriptors' dirty state, identified as > FEAT_HDBSS. The goal of this feature is to reduce the cost of surveying > for dirtied granules, with minimal effect on recording when a granule > has been dirtied. > > The purpose of this feature is to make the execution overhead of live > migration lower to both the guest and the host, compared to existing > approaches (write-protect or search stage 2 tables). > > After these patches, users(such as qemu) can use the > KVM_CAP_ARM_HW_DIRTY_STATE_TRACK ioctl to enable or disable the HDBSS > feature before and after the live migration. > > This feature is similar to Intel's Page Modification Logging (PML), > offering hardware-assisted dirty tracking to reduce live migration > overhead. With PML support expanding beyond Intel, HDBSS introduces a > comparable mechanism for ARM. Where is the change log describing what was changed compared to the previous version? We gave you extensive comments back in March. You never replied to the feedback. And you now dump a whole set of patches, 6 months later, without the slightest indication of what has changed? Why should we make the effort to review this again? M. -- Without deviation from the norm, progress is not possible.