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Wed, 15 Dec 2021 15:53:43 +0000 (GMT) Received: from b03ledav003.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4807C6A05F; Wed, 15 Dec 2021 15:53:42 +0000 (GMT) Received: from [9.211.79.24] (unknown [9.211.79.24]) by b03ledav003.gho.boulder.ibm.com (Postfix) with ESMTP; Wed, 15 Dec 2021 15:53:42 +0000 (GMT) Message-ID: <6103b709-f29d-16f2-7fe6-f9a25dd85b89@linux.ibm.com> Date: Wed, 15 Dec 2021 10:53:41 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [PATCH 00/12] s390x/pci: zPCI interpretation support Content-Language: en-US To: Pierre Morel , qemu-s390x@nongnu.org References: <20211207210425.150923-1-mjrosato@linux.ibm.com> From: Matthew Rosato In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: rZTakHygPATYXQMgPqBIpS7KJEG0lFFD X-Proofpoint-GUID: JJzUQk76eFw-7sT_0yiC6hgY_bOoacpZ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-15_10,2021-12-14_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 spamscore=0 phishscore=0 suspectscore=0 clxscore=1015 bulkscore=0 adultscore=0 malwarescore=0 mlxscore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112150088 Received-SPF: pass client-ip=148.163.156.1; envelope-from=mjrosato@linux.ibm.com; helo=mx0a-001b2d01.pphosted.com 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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-1.64, 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: farman@linux.ibm.com, kvm@vger.kernel.org, schnelle@linux.ibm.com, cohuck@redhat.com, richard.henderson@linaro.org, thuth@redhat.com, qemu-devel@nongnu.org, pasic@linux.ibm.com, alex.williamson@redhat.com, mst@redhat.com, pbonzini@redhat.com, david@redhat.com, borntraeger@linux.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/15/21 2:35 AM, Pierre Morel wrote: > > > On 12/7/21 22:04, Matthew Rosato wrote: >> Note:  The first 3 patches of this series are included as pre-reqs, but >> should be pulled via a separate series.  Also, patch 5 is needed to >> support 5.16+ linux header-sync and was already done by Paolo but not >> merged yet so is thus included here as well. >> >> For QEMU, the majority of the work in enabling instruction interpretation >> is handled via new VFIO ioctls to SET the appropriate interpretation and >> interrupt forwarding modes, and to GET the function handle to use for >> interpretive execution. >> >> This series implements these new ioctls, as well as adding a new, >> optional >> 'intercept' parameter to zpci to request interpretation support not be >> used >> as well as an 'intassist' parameter to determine whether or not the >> firmware assist will be used for interrupt delivery or whether the host >> will be responsible for delivering all interrupts. > > In which circumstances do we have an added value by not using interrupt > delivered by firmware? > Disabling it can be a tool to debug and assist in problem determination, but that's about the only scenario I can think of where you would intentionally want to disable intassist. Perhaps then it's not worth leaving in place.