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Wed, 15 Dec 2021 13:57:31 +0000 (GMT) Received: from [9.171.32.186] (unknown [9.171.32.186]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 15 Dec 2021 13:57:31 +0000 (GMT) Message-ID: <28d795f7-e3f7-e64d-88eb-264a30167961@de.ibm.com> Date: Wed, 15 Dec 2021 14:57:31 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.3.0 Subject: Re: [RFC PATCH v5 1/1] KVM: s390: Clarify SIGP orders versus STOP/RESTART Content-Language: en-US To: David Hildenbrand , Eric Farman , Janosch Frank , Claudio Imbrenda , Thomas Huth Cc: Heiko Carstens , Vasily Gorbik , kvm@vger.kernel.org, linux-s390@vger.kernel.org References: <20211213210550.856213-1-farman@linux.ibm.com> <20211213210550.856213-2-farman@linux.ibm.com> <3832e4ab-ffb7-3389-908d-99225ccea038@redhat.com> From: Christian Borntraeger In-Reply-To: <3832e4ab-ffb7-3389-908d-99225ccea038@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: C66EkEN1bTGfKgxHinpTApwdGbwD5J8o X-Proofpoint-ORIG-GUID: CpNU_36gU5tazeRIR06KC2W53M4wZywX 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_09,2021-12-14_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 mlxscore=0 suspectscore=0 spamscore=0 adultscore=0 malwarescore=0 clxscore=1015 priorityscore=1501 mlxlogscore=999 lowpriorityscore=0 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112150077 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org Am 15.12.21 um 14:24 schrieb David Hildenbrand: > On 13.12.21 22:05, Eric Farman wrote: >> With KVM_CAP_S390_USER_SIGP, there are only five Signal Processor >> orders (CONDITIONAL EMERGENCY SIGNAL, EMERGENCY SIGNAL, EXTERNAL CALL, >> SENSE, and SENSE RUNNING STATUS) which are intended for frequent use >> and thus are processed in-kernel. The remainder are sent to userspace >> with the KVM_CAP_S390_USER_SIGP capability. Of those, three orders >> (RESTART, STOP, and STOP AND STORE STATUS) have the potential to >> inject work back into the kernel, and thus are asynchronous. >> >> Let's look for those pending IRQs when processing one of the in-kernel >> SIGP orders, and return BUSY (CC2) if one is in process. This is in >> agreement with the Principles of Operation, which states that only one >> order can be "active" on a CPU at a time. >> >> Suggested-by: David Hildenbrand >> Signed-off-by: Eric Farman >> --- > > In general, LGTM. As raised, with SIGP RESTART there are other cases we > could fix in the kernel, but they are of very low priority IMHO. Does that qualify as an RB, assuming that we can fix the other cases later on?