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([2001:b07:6468:f312:ec2c:90a9:1236:ebc6]) by smtp.gmail.com with ESMTPSA id z13sm25261492wro.97.2020.09.22.02.04.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Sep 2020 02:04:53 -0700 (PDT) Subject: Re: [PATCH 2/6] block/nvme: Map doorbells pages write-only To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Fam Zheng , Stefan Hajnoczi , qemu-devel@nongnu.org References: <20200921162949.553863-1-philmd@redhat.com> <20200921162949.553863-3-philmd@redhat.com> <6ea4b96862a0dac22205592b6c8d9e21ab57189a.camel@euphon.net> <22dab788-06f1-3686-51f3-24ee7ce77fda@redhat.com> From: Paolo Bonzini Message-ID: Date: Tue, 22 Sep 2020 11:04:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <22dab788-06f1-3686-51f3-24ee7ce77fda@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Received-SPF: pass client-ip=216.205.24.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/22 00:31:51 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.455, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action 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: Kevin Wolf , qemu-block@nongnu.org, Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 22/09/20 10:41, Philippe Mathieu-Daudé wrote: >> Besides looking more correct in access mode, is there any side effect >> of WO mapping? > TBH I don't have enough knowledge to answer this question. > I tested successfully on X86. I'm writing more tests. No problem with doing this, but PROT_WRITE does not work at all on x86. :) PROT_EXEC works if you have a machine with PKRU, but PROT_WRITE silently becomes PROT_READ|PROT_WRITE because the processor does not support it. Paolo