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[91.12.96.155]) by smtp.gmail.com with ESMTPSA id r20sm1146840wmd.37.2021.12.15.06.02.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 15 Dec 2021 06:02:19 -0800 (PST) Message-ID: Date: Wed, 15 Dec 2021 15:02:18 +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: [RFC PATCH v5 1/1] KVM: s390: Clarify SIGP orders versus STOP/RESTART Content-Language: en-US To: Christian Borntraeger , 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> <28d795f7-e3f7-e64d-88eb-264a30167961@de.ibm.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <28d795f7-e3f7-e64d-88eb-264a30167961@de.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On 15.12.21 14:57, Christian Borntraeger wrote: > > > 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? > Certainly an Acked-by: David Hildenbrand , to fully review I need some more time (maybe tomorrow) -- Thanks, David / dhildenb