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bh=PFzKoHqZVN58xXzW9REjb7dVMfQ+d82D122kA9U6f7Q=; b=Sp+UT/PWaNf6+9k4TkPzL6XMgssqBQcR8eBOTUtiKh5JRguXas5hK/jMoPftrAU570ItE2 EO6hFecpyyUqjIbIJ4sSqvKa/grFFl4bYg/EEGjr5wUZFu1O6jySxTd7tdP9qzHijetOUE yLQrudbQsrqaNJWCmtLOnOw1S+7Qvyc= X-MC-Unique: IMHxHxCWPJK4Qr_q3Yrmzw-1 From: Cornelia Huck To: Peter Maydell Subject: [PULL 7/8] vfio-ccw: Do not read region ret_code after write Date: Fri, 5 Mar 2021 16:55:16 +0100 Message-Id: <20210305155517.1604547-8-cohuck@redhat.com> In-Reply-To: <20210305155517.1604547-1-cohuck@redhat.com> References: <20210305155517.1604547-1-cohuck@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=cohuck@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eric Farman , qemu-s390x@nongnu.org, Cornelia Huck , qemu-devel@nongnu.org, Matthew Rosato Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" From: Eric Farman A pwrite() call returns the number of bytes written (or -1 on error), and vfio-ccw compares this number with the size of the region to determine if an error had occurred or not. If they are not equal, this is a failure and the errno is used to determine exactly how things failed. An errno of zero is possible (though unlikely) in this situation and would be translated to a successful operation. If they ARE equal, the ret_code field is read from the region to determine how to proceed. While the kernel sets the ret_code field as necessary, the region and thus this field is not "written back" to the user. So the value can only be what it was initialized to, which is zero. So, let's convert an unexpected length with errno of zero to a return code of -EFAULT, and explicitly set an expected length to a return code of zero. This will be a little safer and clearer. Suggested-by: Matthew Rosato Signed-off-by: Eric Farman Message-Id: <20210303160739.2179378-1-farman@linux.ibm.com> Signed-off-by: Cornelia Huck --- hw/vfio/ccw.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c index bc78a0ad7638..b2df708e4b01 100644 --- a/hw/vfio/ccw.c +++ b/hw/vfio/ccw.c @@ -104,9 +104,9 @@ again: goto again; } error_report("vfio-ccw: write I/O region failed with errno=3D%d", = errno); - ret =3D -errno; + ret =3D errno ? -errno : -EFAULT; } else { - ret =3D region->ret_code; + ret =3D 0; } switch (ret) { case 0: @@ -192,9 +192,9 @@ again: goto again; } error_report("vfio-ccw: write cmd region failed with errno=3D%d", = errno); - ret =3D -errno; + ret =3D errno ? -errno : -EFAULT; } else { - ret =3D region->ret_code; + ret =3D 0; } switch (ret) { case 0: @@ -232,9 +232,9 @@ again: goto again; } error_report("vfio-ccw: write cmd region failed with errno=3D%d", = errno); - ret =3D -errno; + ret =3D errno ? -errno : -EFAULT; } else { - ret =3D region->ret_code; + ret =3D 0; } switch (ret) { case 0: --=20 2.26.2