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 D2B47C5CFCF for ; Fri, 14 Aug 2026 16:26:27 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From: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=axm9DDg7/F1CyalXq6Y0UQsX8AkJAu95f6HQXMokHlg=; b=FQdB2gnnFr61cJbMRU2HUuN1qJ 5XSW1E/A9jpg6RdwxlmhLbiFQzSHFn9DR39Ky4TNQbSVIboNofqeMqPARrMuoPl6oEx0k4X/m04lw XAsLULjEtLfZCNQGlJ7odgnXop3IFoidwcpmoMuTS4LWqmt0xz30wDt6JfohztwUgCDx8Wjbz9V3C JQxdo3r29Z+TxQxPdDFwEvkV6PZjftNkbwd42H9QnqkmHcHAXNkfRQskc43usBnIU1LjMsS0QKiNz byxnrd58Gx6DBMvrZ+1rHkbT+Z+pmDUUQXXbvAZ/Sh+pLA5rgwkjxQPiebhMomW4h42aWwNI7Og8x srrnrwDQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wuujW-00000002v4L-2ERk; Fri, 14 Aug 2026 16:26:16 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wuujR-00000002v3c-2cT1 for linux-arm-kernel@lists.infradead.org; Fri, 14 Aug 2026 16:26:10 +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 175141596; Fri, 14 Aug 2026 09:26:01 -0700 (PDT) Received: from raptor (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id DC3FF3F632; Fri, 14 Aug 2026 09:26:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1786724765; bh=MTPBOHQFJvYtb+AHcGvBZoYpVjfEnZJvBa0lWB+9N4g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DWgoTJHqOCjad3GIisdj3ANJUPRHIZpHgG+PT2LH+0PtFsBB96Dx1ZWBk/dLSVIz+ lWRVVd6FJRFZeOnqUQYcjh+8S6wGBxgK1yknbk6JSYoFK6km4YAdjMZ7aIaOXQKrjf JFfOrlqAtKTXo1ga4xKDGaXnVaQRHXeH2UegfyMA= Date: Fri, 14 Aug 2026 17:26:00 +0100 From: Alexandru Elisei To: Sean Christopherson Cc: David Hildenbrand , Mark Rutland , pbonzini@redhat.com, kvm@vger.kernel.org, maz@kernel.org, oupton@kernel.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, fuad.tabba@linux.dev Subject: Re: [RFC PATCH 0/3] KVM: Dirty page logging for guest_memfd-only memslots Message-ID: References: <487aa57c-72ad-453b-971d-ca24a8380429@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260814_092609_706612_53B3A9E4 X-CRM114-Status: GOOD ( 18.42 ) 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 Hi, On Fri, Aug 14, 2026 at 09:04:46AM -0700, Sean Christopherson wrote: > On Fri, Aug 14, 2026, Alexandru Elisei wrote: > > On Fri, Aug 14, 2026 at 06:03:54AM -0700, Sean Christopherson wrote: > > > > That would be in contrast to user space having to guess that page migration on > > > > the current hardware with the current guest_memfd implementation does not > > > > support page migration, to then disable exactly that. > > > > If guest_memfd picks up support for another feature that might lead to > > memory being unmapped from stage 2 without userspace initiating it, would > > you be ok with that feature being gated by another guest_memfd flag? > > Yes, absolutely. FWIW, if I get my way and reclaim is driven by userspace, then > hopefully such a feature never comes along. But if guest_memfd does gain some > feature that triggers invalidations, then yeah, at the very least it would need > to have some knowledge of whether or not the associated VM supports said feature. > > > I get the feeling we're all on the same page, that guest_memfd will support > > a mode where memory isn't unmapped from stage 2, and right now the > > discussion is more about how that will be implemented. > > Ya. That's great, thanks for confirming. Alex