From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 5DA0528B4FA; Wed, 23 Sep 2026 00:33:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790123604; cv=none; b=Lpif08e1IRAW/hpIr/wnPlLifiOct+JlScNRtYlJy3PYNWqLlZ/TjXMUS2lSAIrNBzON+gf9pnonyTnwxc5ecGmV4DjPzobSFuDUwH8oALJLjY8MksHqcNkYa/GZOzpIKvcXOlrYBx5wFuFMqRRuxJ6VkVJGwRkCbpk0xs7iNPw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790123604; c=relaxed/simple; bh=77i3zYEPqhl4Ykq7WhP+J7mIM1DnI3AO6zla9d0ZiPw=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=AGaYWi+u7SkHT86jO6y/GlAawXZdGdEipj0MpJumkAw68IGQI9AET3jfT1GBCBBwV8R8L5cyJ2pOZPbVThNrRT0GRdzFZpJgEYREjNt53AlykjEcHQ5t+7CX3p5b67ppf3llvqXR7R4CLodirJeWLaMIDIzYde51m4s1zrhvqjY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=oRgWkLcQ; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="oRgWkLcQ" 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 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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 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