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[83.57.168.62]) by smtp.gmail.com with ESMTPSA id d9sm2022577wre.52.2021.11.10.23.51.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Nov 2021 23:51:23 -0800 (PST) Message-ID: Date: Thu, 11 Nov 2021 08:51:22 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH 1/2] virtio: use virtio accessor to access packed descriptor flags To: Jason Wang , mst@redhat.com References: <20211111063854.29060-1-jasowang@redhat.com> From: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= In-Reply-To: <20211111063854.29060-1-jasowang@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=philmd@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=philmd@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -74 X-Spam_score: -7.5 X-Spam_bar: ------- X-Spam_report: (-7.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-3.999, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: eperezma@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 11/11/21 07:38, Jason Wang wrote: > We used to access packed descriptor flags via > address_space_{write|read}_cached(). When we hit the cache, memcpy() > is used which is not an atomic operation which may lead a wrong value > is read or wrote. > > So this patch switches to use virito_{stw|lduw}_phys_cached() to make > sure the aceess is atomic. > > Fixes: 86044b24e865f ("virtio: basic packed virtqueue support") > Cc: qemu-stable@nongnu.org > Signed-off-by: Jason Wang > --- > hw/virtio/virtio.c | 11 ++++------- > 1 file changed, 4 insertions(+), 7 deletions(-) Reviewed-by: Philippe Mathieu-Daudé