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 66A40C98308 for ; Wed, 23 Sep 2026 00:33:32 +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:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=kls9Aeh3ft2h2p7XC+gtGs+6aohVBMrr1+4HHRXk/ks=; b=a8u97UZTjimhykgP9mafFZ4iDb Y4uDkx8L4sxOjXXj+h16+6eBOmhcHbjYvlpVo3B2aAZrae+RXdfww9QF/GJG8nmTMDTR5SEtoY4LO 3hDwQap1wutw7PKEyqtgUZ7K8WTqSdu+H70iO7dcZWLJIpZQW+vQ8PRPo2ksYzzvbx8oPdxH8uCCF 0kfJxx3kUoq5yws5vLQ8b/QOWe5DVjzelfr3Lvnqdqq6SHYoZlznKg7/LDHAl9KlYkKGMr74GxRtT mbn7r+eC4xmpZbsK/OMLxWuqS2OlxcfdQBIXqJOPauXiG346SJ8TqsB/YI5SyfofPfFdc2hEdQH1+ N28t6EvQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9AvN-00000006nbS-2dql; Wed, 23 Sep 2026 00:33:25 +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 1x9AvL-00000006nb3-1t6G for linux-arm-kernel@lists.infradead.org; Wed, 23 Sep 2026 00:33:24 +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 223E51576; Tue, 22 Sep 2026 17:33:18 -0700 (PDT) Received: from [10.57.9.113] (unknown [10.57.9.113]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A2AE63F86C; Tue, 22 Sep 2026 17:33:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790123601; bh=77i3zYEPqhl4Ykq7WhP+J7mIM1DnI3AO6zla9d0ZiPw=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=oRgWkLcQ31WqXE0HZzy2oda8oXCF5KyAJJ1hOCVglmH0esN1QobUgRqjxsKQ0rnUF HcEHi0aN57b3J02f+zBZVVZvI20ki3Y3HdxMh4KN/vl1I33mR4KWfrvwABIFz7re3G vAjp9bLwL/VO4cIRYlc8jfWw+ejPv0v1LHN4Olh4= Message-ID: <19c4acf0-bc5a-4856-96c7-bf19c2d989e7@arm.com> Date: Wed, 23 Sep 2026 01:33:17 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v7 02/13] mm: Add an allocator for CoCo shared memory Content-Language: en-GB To: Jason Gunthorpe , Catalin Marinas Cc: "Aneesh Kumar K.V (Arm)" , linux-coco@lists.linux.dev, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, Andrew Morton , christian.koenig@amd.com, Joerg Roedel , Marc Zyngier , Marek Szyprowski , Robin Murphy , Steven Price , Sumit Semwal , Thomas Gleixner , Will Deacon , dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, linux-media@vger.kernel.org, linux-mm@kvack.org References: <20260921144847.501151-1-aneesh.kumar@kernel.org> <20260921144847.501151-3-aneesh.kumar@kernel.org> <20260922165147.GD1540250@ziepe.ca> From: Suzuki K Poulose In-Reply-To: <20260922165147.GD1540250@ziepe.ca> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260922_173323_531110_57A53356 X-CRM114-Status: GOOD ( 10.43 ) 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 22/09/2026 17:51, Jason Gunthorpe wrote: > On Tue, Sep 22, 2026 at 05:25:58PM +0100, Catalin Marinas wrote: >> Does the memset() post sharing logic work for pKVM as well? If nothing >> clears it, we have a small window where guest data is leaked to the >> host. > > Same question for RMM? Or did they define that the RMM zeros on these > transitions? RMM doesn't "define" what exactly is written when a granule is transitioned to "DELEGATED" or "UNDELEGATED". But does guarantee that the contents are wiped after the transition. This may be: * RMM writing random bytes or 0s * Changing the MEC of the location. See section A2.3.8 Granule wiping DEN0137 2.0-bet3 Cheers Suzuki