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[64.229.69.35]) by smtp.gmail.com with ESMTPSA id c12sm1483684qkc.81.2019.09.11.08.07.15 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 11 Sep 2019 08:07:16 -0700 (PDT) From: Richard Henderson To: David Hildenbrand , qemu-devel@nongnu.org References: <20190906075750.14791-1-david@redhat.com> <20190906075750.14791-5-david@redhat.com> <7788b1b6-fbf0-3370-5563-1da4f7124999@linaro.org> Openpgp: preference=signencrypt Message-ID: <905250c7-b249-6812-391c-408af69d9523@linaro.org> Date: Wed, 11 Sep 2019 11:07:14 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <7788b1b6-fbf0-3370-5563-1da4f7124999@linaro.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2607:f8b0:4864:20::841 Subject: Re: [Qemu-devel] [PATCH v2 04/28] s390x/tcg: MVCL: Process max 2k bytes at a time X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Florian Weimer , Thomas Huth , Cornelia Huck , Stefano Brivio , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/11/19 10:52 AM, Richard Henderson wrote: > The code within Hercules breaks the action at every 2k address boundary -- for > both src and dest. That's the only way that actually makes sense to me, as > otherwise we end up allowing userspace to read/write into a page without > permission. Which is a security hole. Also, doesn't "2k" come from the old esa/360 page size? Which means that we could break at 4k pages instead of 2k now and the program wouldn't really be able to tell the difference. r~