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Tue, 20 Jan 2026 15:23:13 +0000 (GMT) Message-ID: Subject: Re: [PATCH] KVM: s390: vsie: retry SIE when unable to get vsie_page From: Eric Farman To: Janosch Frank , Claudio Imbrenda Cc: Christian Borntraeger , David Hildenbrand , Christoph Schlameuss , kvm@vger.kernel.org, linux-s390@vger.kernel.org Date: Tue, 20 Jan 2026 10:23:13 -0500 In-Reply-To: References: <20251217030107.1729776-1-farman@linux.ibm.com> <8334988f-2caa-4361-b0b9-50b9f41f6d8a@linux.ibm.com> <20260114105033.23d3c699@p-imbrenda> <23154a0c6b4b9e625daa2b1bbaadc349bf3a99ed.camel@linux.ibm.com> <3d997b2645c80396c0f7c69f95fd8ec0d4784b20.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 (3.58.2-1.fc43) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: naHqG2ZgSj6wPbHtX4qvQGlWOh4whxzz X-Proofpoint-ORIG-GUID: naHqG2ZgSj6wPbHtX4qvQGlWOh4whxzz X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTIwMDEyNyBTYWx0ZWRfX58ySOYl887Mm wMQn4xbn28JmDtG8l0mk3dVWh909AmvPSqZ6DD5+UJadsMcv216htMPoxo8ZPojbrSTgFv1WEbU GfPG4109r/7wkfMohGIo5ThgBrUO1D7dn+LVV6ypffeB0GVUI2lJnwDm+bprx92t2wbvUwDv53g hAlXOxPOP5JgskfMAlQBO/eBUaafvQOoLxvYbtrYJj9A9Ttq5Iap4TUyBWCvdRe8Rn2TBFSogE/ uKwWgaVj9DnVeLJM5u6y8S4JcrsvtSmE0lGmL1Qz4MbYl1JCp6ji/w8thqau0S+kC8mPE94H4NY 26TP/uU/+mMAJ8CpSYWeFxE/yU9JURvSugG2GlAhohqs++DQASJh5ZYR145wtqiI9L42j3Ti8UN 3VEx4pA1A9sdx9hRViBWKInuyv1Znxk09POX//se7ykCcovpbVigUAXgpLfK8AMg2/7tYg4mgd/ 3PzcUooii3Wwza1Ks9w== X-Authority-Analysis: v=2.4 cv=bopBxUai c=1 sm=1 tr=0 ts=696f9de5 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=cP2koYoijfjhQiI88GMA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.20,FMLib:17.12.100.49 definitions=2026-01-20_04,2026-01-20_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 bulkscore=0 adultscore=0 suspectscore=0 impostorscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2601150000 definitions=main-2601200127 On Mon, 2026-01-19 at 15:49 +0100, Janosch Frank wrote: > On 1/16/26 16:45, Eric Farman wrote: > > On Thu, 2026-01-15 at 16:17 -0500, Eric Farman wrote: > > > On Wed, 2026-01-14 at 10:50 +0100, Claudio Imbrenda wrote: > > > > On Mon, 05 Jan 2026 10:46:53 -0500 > > > > Eric Farman wrote: > > > >=20 > > > > > On Mon, 2026-01-05 at 13:41 +0100, Janosch Frank wrote: > > > > > > On 12/17/25 04:01, Eric Farman wrote: > > > > > > > SIE may exit because of pending host work, such as handling a= n interrupt, > > > > > > > in which case VSIE rewinds the guest PSW such that it is tran= sparently > > > > > > > resumed (see Fixes tag). There is still one scenario where th= ose conditions > > > >=20 > > > > can you add a few words to (very briefly) explain what the scenario= is? > > >=20 > > > Maybe if this paragraph were rewritten this way, instead? > > >=20 > > > --8<-- > > > SIE may exit because of pending host work, such as handling an interr= upt, > > > in which case VSIE rewinds the guest PSW such that it is transparentl= y > > > resumed (see Fixes tag). Unlike those other places that return rc=3D0= , this > > > return leaves the guest PSW in place, requiring the guest to handle a= n > > > intercept that was meant to be serviced by the host. This showed up w= hen > > > testing heavy I/O workloads, when multiple vcpus attempted to dispatc= h the > > > same SIE block and incurred failures inserting them into the radix tr= ee. > > > -->8-- > >=20 > > Spoke to Claudio offline, and he suggested the following edit to the ab= ove: > >=20 > > --8<-- > > SIE may exit because of pending host work, such as handling an interrup= t, > > in which case VSIE rewinds the guest PSW such that it is transparently > > resumed (see Fixes tag). Unlike those other places that return rc=3D0, = this > > return leaves the guest PSW in place, requiring the guest to handle a > > spurious intercept. This showed up when testing heavy I/O workloads, > > when multiple vcpus attempted to dispatch the same SIE block and incurr= ed > > failures inserting them into the radix tree. > > -->8-- > >=20 > > >=20 > > > @Janosch, if that ends up being okay, can you update the patch or do = you want me to send a v2? >=20 > I can fix that up. Great, thank you!