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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-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CEB341A0004 X-Stat-Signature: pijx3jtdkjm7itrcj47o5qy9xzuwehra X-Rspam-User: X-HE-Tag: 1790123602-358853 X-HE-Meta: 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 e0GzKRi/ e+g2xPzpWr2qBZ25bv5XptJqNH5TSRMujAOrHxIIbrdzdelNT7BDq1aacI3Qx4YB3bdNypo2iEb72qrtPE+/xeqSH7aDvyykUdRF5O0/8HjvsQdLFxogP8d3OKvAYXK01X7HdftnYeL9SB8vAkgU/Ll7KwY52VRoGQnDcGahnnLgtCgyq+acrReotn/f6s91RDKkZ5RVH9239BNI9zxA30GTJJ6vqByNhGyhzQy6ShDIb0oY= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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