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Wed, 14 Jan 2026 09:50:35 +0000 (GMT) Date: Wed, 14 Jan 2026 10:50:33 +0100 From: Claudio Imbrenda To: Eric Farman Cc: Janosch Frank , Christian Borntraeger , David Hildenbrand , Christoph Schlameuss , kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [PATCH] KVM: s390: vsie: retry SIE when unable to get vsie_page Message-ID: <20260114105033.23d3c699@p-imbrenda> In-Reply-To: References: <20251217030107.1729776-1-farman@linux.ibm.com> <8334988f-2caa-4361-b0b9-50b9f41f6d8a@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.3.1 (GTK 3.24.49; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: MeTCOU4mqlL8xflEo6YzjpvJGJgq72Xw X-Authority-Analysis: v=2.4 cv=LLxrgZW9 c=1 sm=1 tr=0 ts=696766f0 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=kj9zAlcOel0A:10 a=vUbySO9Y5rIA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VnNF1IyMAAAA:8 a=nFgxaL2sVcJjB0vxDwoA:9 a=NqO74GWdXPXpGKcKHaDJD/ajO6k=:19 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTE0MDA3OSBTYWx0ZWRfX3jylQwItDDhN 8GbsYp7q//96kYp7FDRoTqVahwwjt7tYDBEvG/1uU0YWXmElLhyUP/13dM2J5i6L/9yZCtveXWJ RPP42m6KDCr1p54DxOisGBGyZLWVKWTMxe9hP19gCI+gdF8wAlXILMN1jDrDMMPrfnWsZzPBad3 NnC7KSsjK52l0aouT6ChRoju5cnbl9sQGnjuTHiiP6dhrLODW3x4Q+jzCsboDWLuemTbwkbXuTQ daNb1BtqfbHg1f6NBCr4kLrZ21YEiV9e+IzBIXamKqV8Ca7tVl45+1WNwkL3Wwq8kFUDZJBfkmW ElnNMK8CFpfkrWJCWazXY3s/JKRhWL+n3aBGxoBRz+9z3qmbu2nf5uUDs953Q/Nb3iBJbAair2t DyOMMiJgokbmMeUa0j6AuXbOkEkKR/n7FcjVgZFbXReyGdbmTReyAGL36XUrBaBN56CNcOhA/C4 +xKHts9dPKD6uhgtB+Q== X-Proofpoint-ORIG-GUID: MeTCOU4mqlL8xflEo6YzjpvJGJgq72Xw X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.9,FMLib:17.12.100.49 definitions=2026-01-14_03,2026-01-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 clxscore=1011 spamscore=0 impostorscore=0 malwarescore=0 phishscore=0 adultscore=0 lowpriorityscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2512120000 definitions=main-2601140079 On Mon, 05 Jan 2026 10:46:53 -0500 Eric Farman wrote: > 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 an interrupt, > > > in which case VSIE rewinds the guest PSW such that it is transparently > > > resumed (see Fixes tag). There is still one scenario where those conditions can you add a few words to (very briefly) explain what the scenario is? > > > are not present, but that the VSIE processor returns with effectively rc=0, > > > resulting in additional (and unnecessary) guest work to be performed. > > > > > > For this case, rewind the guest PSW as we do in the other non-error exits. > > > > > > Fixes: 33a729a1770b ("KVM: s390: vsie: retry SIE instruction on host intercepts") > > > Signed-off-by: Eric Farman > > > > This is purely cosmetic to have all instances look the same, right? > > Nope, I can take this path with particularly high I/O loads on the system, which ends up > (incorrectly) sending the intercept to the guest. this is a good candidate for the explanation I mentioned above :) (the patch itself looks fine)