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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D415C433FE for ; Fri, 30 Sep 2022 09:28:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231266AbiI3J2w (ORCPT ); Fri, 30 Sep 2022 05:28:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46860 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231459AbiI3J2i (ORCPT ); Fri, 30 Sep 2022 05:28:38 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8D98E3186 for ; Fri, 30 Sep 2022 02:28:37 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7388A620B0 for ; Fri, 30 Sep 2022 09:28:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C89E3C433B5; Fri, 30 Sep 2022 09:28:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1664530116; bh=x8HabbATdkexho2Sr0YyoN1UguAw5LEKb1ooDCEczWA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=XiGI6MJbTcOcLVa20KljaOzWsAiDUE/7AYz514QbjYY7fB6/lOlwlReZovBCV+BWp D7dJz/843OOuZbMepRKDxOXqg0FS1tt4+jgU0mRfCR3yZzbTr14tOmFpn0Q0j4fcNh 6u39iIQOf9s6LlHOol/7ol4OwbpKwPR2+mKXB9FD5q4AmtRz/jkoZN0N0bUNIipvEe tuCGgj7zscF4DPo2ZKIHqRTjhIkCBYkrMLZVuQ5JNmJWZhpfJ5+ayqL6eJTWULqOsg g/+ZtLbLpG3ryT/lzlT8qXS0cwoOOevpIWzzycGj66b7cckFvF6rM9Re2RmdGkJbje ku5QfXzb32hUw== 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 1oeCJu-00Dj63-NC; Fri, 30 Sep 2022 10:28:34 +0100 Date: Fri, 30 Sep 2022 10:28:34 +0100 Message-ID: <86a66h6wjh.wl-maz@kernel.org> From: Marc Zyngier To: Peter Xu Cc: Gavin Shan , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, catalin.marinas@arm.com, bgardon@google.com, shuah@kernel.org, andrew.jones@linux.dev, will@kernel.org, dmatlack@google.com, pbonzini@redhat.com, zhenyzha@redhat.com, shan.gavin@gmail.com, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, oliver.upton@linux.dev Subject: Re: [PATCH v4 3/6] KVM: arm64: Enable ring-based dirty memory tracking In-Reply-To: References: <20220927005439.21130-1-gshan@redhat.com> <20220927005439.21130-4-gshan@redhat.com> <86sfkc7mg8.wl-maz@kernel.org> <320005d1-fe88-fd6a-be91-ddb56f1aa80f@redhat.com> <87y1u3hpmp.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/27.1 (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: peterx@redhat.com, gshan@redhat.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, catalin.marinas@arm.com, bgardon@google.com, shuah@kernel.org, andrew.jones@linux.dev, will@kernel.org, dmatlack@google.com, pbonzini@redhat.com, zhenyzha@redhat.com, shan.gavin@gmail.com, james.morse@arm.com, suzuki.poulose@arm.com, alexandru.elisei@arm.com, oliver.upton@linux.dev X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Thu, 29 Sep 2022 15:32:03 +0100, Peter Xu wrote: > > > If I'm correct, Marc may be talking about SMMU, which is emulated in host > > instead of QEMU. In this case, the DMA target pages are similar to those > > pages for vgic/its tables. Both sets of pages are invisible from QEMU. > > OK, I'm not aware the SMMU can also be emulated in the host kernel, thanks > Gavin. If so then we really need to think as I mentioned above since we > will only sync this when switchover, and if the DMA range can cover a large > portion of guest mem (assuming the physical pages to DMA can be randomly > allocated by guest device drivers) then it may be another problem to cause > drastic downtime. I don't know where this is coming from. The kernel has no SMMU emulation at all. M. -- Without deviation from the norm, progress is not possible.