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 E33E234D385; Fri, 21 Nov 2025 09:54:44 +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=1763718885; cv=none; b=AN+z8oQJzaZH8skMOkwt0Go6ijosyLK1jFCqohiuAd5NC4pCxc7mMETBDwqdVhhhEk2KbcQL5cxs1IlPOkiIwdnfU7erbIFiNgMpZRqv6dP4MslHsS3Lrntx03dTd1mZEgHIPZQQqLiOS2q08EjZJOWdjBMDkwfjJ4ujp/QJwhA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763718885; c=relaxed/simple; bh=ckVGtchhklPTh0H5XGrkBBtZKAvAc7k3gSAzJOeSpQs=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=b73q+4ed/Ncyjcq6LBFQStS3aqzr9xJOgYnMqWj43f23LO9eGYod4EtPy/Ovxz4DllBnZSJrJedb9k7V5QBOfpPjG0pW//ETedDcThAXdFo3h3Jr9Q2eC7qB+fz6VEZZgjBuFrSRZQgDr15eRyVWEQEpWPsja1+Xr/4Jx+xREaE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cvAIznXb; 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="cvAIznXb" 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) Precedence: bulk X-Mailing-List: linux-doc@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=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 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.