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 B8277109B46D for ; Tue, 31 Mar 2026 14:14:15 +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:Message-ID:Date:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=u2fGGIf4no/o//tYkizMZzVURETL1fEqQakfZPBw6+k=; b=hHakorYKXj27obHqxNhkOh6EGp 6cgDdOq6HdmPu3BkndYVIFm1v8NlfmtrTWqzkiUfUzIjfTddUpRo4FA0z3ViGtIQv1sd0sFhuk8j7 p34pxY/lwo97t9HVcvuJexD8SXxJBtwmZtIBDWHjapkdrvGVg21aC40+heb6VuecWwEYI5Dh5y2Sp Yn82Xv25WL2kpVrfCefnpzv8G8pgC8tm2uy/k/n+YHi3rQg3FwJK5HFM3JYrr0bWKG00GaS+n1JxO ylKGBNENRoRpimJKVoFEJvi+NTo3Sysa3fXHmW36Br44IN3SE7GgPcmqTremUKV8vm8DdkKVsZMR6 QtINvd6g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w7Zr8-0000000D3X6-0ZyE; Tue, 31 Mar 2026 14:14:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w7Zr4-0000000D3Ve-2Yl0 for linux-arm-kernel@lists.infradead.org; Tue, 31 Mar 2026 14:14:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1565249C7; Tue, 31 Mar 2026 07:13:57 -0700 (PDT) Received: from devkitleo.cambridge.arm.com (devkitleo.cambridge.arm.com [10.1.196.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BC9EF3F641; Tue, 31 Mar 2026 07:13:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774966442; bh=0WokdVZGVQOySMRtOFuViCjuFlNJiqco1s6MePa8OP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SLROPAAq4tm06CZlvLbnK6UlSl74cbeF4PnQYHt9YVrFbK4s7f7jkSNb87VbkRboy XXkf4Lg/itNksvkyv6pSBDL/ICC5mCXYYcQ0SnbvaUsn7q3qpwFoRaJP/O5WcrtsmP 3Bp268ytYRpb6dxbptQOk8QvUD84hzofzk3QHT0g= From: Leonardo Bras To: Tian Zheng Cc: Leonardo Bras , maz@kernel.org, oupton@kernel.org, catalin.marinas@arm.com, corbet@lwn.net, pbonzini@redhat.com, will@kernel.org, yuzenghui@huawei.com, wangzhou1@hisilicon.com, liuyonglong@huawei.com, Jonathan.Cameron@huawei.com, yezhenyu2@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, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, suzuki.poulose@arm.com Subject: Re: [PATCH v3 0/5] Support the FEAT_HDBSS introduced in Armv9.5 Date: Tue, 31 Mar 2026 15:13:50 +0100 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260225040421.2683931-1-zhengtian10@huawei.com> References: <20260225040421.2683931-1-zhengtian10@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260331_071406_803160_12378432 X-CRM114-Status: GOOD ( 24.38 ) 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 Wed, Feb 25, 2026 at 12:04:16PM +0800, 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. This feature utilizes hardware assistance to achieve dirty > page tracking, aiming to significantly reduce the overhead of scanning > for dirty pages. > > 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. > > v2: > https://lore.kernel.org/linux-arm-kernel/20251121092342.3393318-1-zhengtian10@huawei.com/ > > v2->v3 changes: > - Remove the ARM64_HDBSS configuration option and ensure this feature > is only enabled in VHE mode. > - Move HDBSS-related variables to the arch-independent portion of the > kvm structure. > - Remove error messages during HDBSS enable/disable operations > - Change HDBSS buffer flushing from handle_exit to vcpu_put, > check_vcpu_requests, and kvm_handle_guest_abort. > - Add fault handling for HDBSS including buffer full, external abort, > and general protection fault (GPF). > - Add support for a 4KB HDBSS buffer size, mapped to the value 0b0000. > - Add a second argument to the ioctl to turn HDBSS on or off. > > Tian Zheng (1): > KVM: arm64: Document HDBSS ioctl > > eillon (4): > arm64/sysreg: Add HDBSS related register information > KVM: arm64: Add support to set the DBM attr during memory abort > KVM: arm64: Add support for FEAT_HDBSS > KVM: arm64: Enable HDBSS support and handle HDBSSF events > > Documentation/virt/kvm/api.rst | 16 +++++ > arch/arm64/include/asm/cpufeature.h | 5 ++ > arch/arm64/include/asm/esr.h | 7 ++ > arch/arm64/include/asm/kvm_host.h | 17 +++++ > arch/arm64/include/asm/kvm_mmu.h | 1 + > arch/arm64/include/asm/kvm_pgtable.h | 4 ++ > arch/arm64/include/asm/sysreg.h | 11 +++ > arch/arm64/kernel/cpufeature.c | 12 ++++ > arch/arm64/kvm/arm.c | 102 +++++++++++++++++++++++++++ > arch/arm64/kvm/hyp/pgtable.c | 6 ++ > arch/arm64/kvm/hyp/vhe/switch.c | 19 +++++ > arch/arm64/kvm/mmu.c | 70 ++++++++++++++++++ > arch/arm64/kvm/reset.c | 3 + > arch/arm64/tools/cpucaps | 1 + > arch/arm64/tools/sysreg | 29 ++++++++ > include/uapi/linux/kvm.h | 1 + > tools/include/uapi/linux/kvm.h | 1 + > 17 files changed, 305 insertions(+) > > -- > 2.33.0 > Hi Tian, I was thinking: maybe instead of putting the HDBSS (and HACDBS) stuff across a bunch of KVM files, we should try to focus them all on a single arch/arm64/kvm/dirty_bit.c file (plus a header such as arch/arm64/include/asm/kvm_dirty_bit.h). What is your opinion on that? Thanks! Leo