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Mon, 11 May 2026 12:56:04 +0000 (GMT) Received: from li-479af74c-31f9-11b2-a85c-e4ddee11713b.ibm.com (unknown [9.61.111.34]) by smtpav01.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 11 May 2026 12:56:04 +0000 (GMT) Message-ID: <2b83784ccde25eeabce8f213ebf2ace727f688d2.camel@linux.ibm.com> Subject: Re: [PATCH v2 1/3] KVM: s390: Toggle operation exception for userspace From: Eric Farman To: Janosch Frank , Christian Borntraeger , Claudio Imbrenda , David Hildenbrand Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org Date: Mon, 11 May 2026 08:56:03 -0400 In-Reply-To: References: <20260507200836.3500368-1-farman@linux.ibm.com> <20260507200836.3500368-2-farman@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.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-Authority-Analysis: v=2.4 cv=ZdQt8MVA c=1 sm=1 tr=0 ts=6a01d1e6 cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=PSjzCw7vbD8hFPKuc84A:9 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: 07f7fw-NgMVccG8vJ8670JkJOcgYHPi1 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTExMDE0MCBTYWx0ZWRfX5CuMEDHHO4Ud jXX+mAdvWNYFRf7lzWTcHprkwbXc31bddEFq3LtLj8r3D4CnjTPKya83ku0+g3/48FQSl4h1u47 FRaNFBaB/Ty1a9eZuYVQ3Gq6BA3QexbkAuCkXscIiSDIl2rcvcSp4E9iSNTXgSGQyHx3MRF/NTQ 1+UDJZqBFzxb29ob3E3xUporFLVyidu0/0AXtspi7SYT/UKyLiTpMvrVjvREjXo19WNYGTUarQg 6hdoTb90onX7CCdJcApJstjpn4lKGsNssWsSeakqOafhsxa6pbIj5uT/zpzCtaUKZezEE5+DZ6N n2Gbjah/FKOjLbRQlGWN2IvTie4Yax4x2liEb1cutg5MCIlzhUf/dS34oFjCa8RUelTp4T5kB/w 02zMEvp9qaQyWe9N+JaBTkVbVrIUQkHNbhMWSvvRUjig3zCT9ikSFI96AGI6ABUsBO5vwtae7Ba 6+5rPzY3b/o83kfXkcQ== X-Proofpoint-GUID: 07f7fw-NgMVccG8vJ8670JkJOcgYHPi1 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-11_03,2026-05-08_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 spamscore=0 phishscore=0 lowpriorityscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 suspectscore=0 clxscore=1015 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604200000 definitions=main-2605110140 On Mon, 2026-05-11 at 10:08 +0200, Janosch Frank wrote: > On 5/7/26 22:08, Eric Farman wrote: > > The KVM_CAP_S390_USER_OPEREXEC capability allows operation exceptions > > to be forwarded to userspace. But the actual enablement at the hardware > > level occurs in kvm_arch_vcpu_postcreate(), and only if STFLE.74 or > > user_instr0 are enabled. The latter is associated with a separate > > capability (KVM_CAP_S390_USER_INSTR0), so the only way this happens > > for the USER_OPEREXEC capability is if STFLE.74 is enabled. KVM > > unconditionally enables this bit in kvm_arch_init_vm(), but the guest > > could disable it from the CPU model and thus ignore this capability. > >=20 > > Add USER_OPEREXEC to the check in kvm_arch_vcpu_postcreate(), such that > > either capability would enable this type of exception. > >=20 >=20 > Naming wise shouldn't this be something like: > KVM: s390: Fix S390_USER_OPEREXEC enablement without stfle 74 >=20 > ? Yeah, that is clearer, and I would be fine with that edit.