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Wed, 12 Aug 2026 12:59:41 +0000 (GMT) Received: from darkmoore (unknown [9.224.78.25]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 12 Aug 2026 12:59:41 +0000 (GMT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Wed, 12 Aug 2026 14:59:36 +0200 Message-Id: From: "Christoph Schlameuss" Cc: , , , , , , , , To: "Claudio Imbrenda" , Subject: Re: [PATCH v2 6/9] KVM: s390: Fix IRQ injection with SIGP Stop and Store Status X-Mailer: aerc 0.22.0 References: <20260812104436.109741-1-imbrenda@linux.ibm.com> <20260812104436.109741-7-imbrenda@linux.ibm.com> In-Reply-To: <20260812104436.109741-7-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=XqfK/1F9 c=1 sm=1 tr=0 ts=6a7c6e42 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VnNF1IyMAAAA:8 a=wj_1A0y2YC5ubAPmoGIA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEyMDEwMiBTYWx0ZWRfX/M1ejYf9LjE+ D/+icbR5067bH5BQKUVbhXj0FGaitOiWp8jTwzZ0S2bzBqIc2Vi+pkwzeSJkqDg4eLK5CtuIDpv mh+cjJcOSVd06kUWcjDunnPxUKHpFEFPi8gnW/chP66Ycum8oPNLKrPuKqNqvmmUBB60PqxnuOw XGYQVGQpq5pyWawBPH3kxM3AEK3uOMMElLLZDXuzZlloA/Yot+l+H0+wObXeU3lgihPtmmAZvQ7 l0mcSxFeRKlpMEqvdY73JdzSVxMInEpxS7vRSjyMnOm5gjr+KyAaR67DTvlujocwvi3DVLvvk9t T29/2TLmmygGtoJnEhkTuT8bGtuRw+fNp7dHGCZLdP103lF4Ocv7KcrVKvzByCGNtEp3Tu9RtTn HLddVqIQnSz7mADv05UgiSxlWrgHwtINtG6gTtjsQr83+KltE9ScvtXnxAItk6ux2RgJHMK1lrV ywF24fXrYnr1QEHJCyg== X-Proofpoint-ORIG-GUID: tC2mWcq06aj-_vM6pmEVq41R8Od3BIlF X-Proofpoint-GUID: tC2mWcq06aj-_vM6pmEVq41R8Od3BIlF X-Proofpoint-Spam-Info: AW1haW4tMjYwODEyMDEwMiBTYWx0ZWRfXyeZboPsW7RbJ UQbqhdzkmYIA43nR4vfBFjX3uuaZF9LqMHm3f6K9Nl/gzpId/mrRcjelrq1AsYcgTr1+PxfnbDq Z6YcYjfJdCjfjmm5QUe3YMRodPRmH1s= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-12_03,2026-08-12_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 spamscore=0 adultscore=0 malwarescore=0 clxscore=1015 suspectscore=0 priorityscore=1501 impostorscore=0 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608120102 On Wed Aug 12, 2026 at 12:44 PM CEST, Claudio Imbrenda wrote: > When __inject_sigp_stop() is called for a Stop and Store Status > operation, if the vCPU is running, the interrupt is marked as pending > and the status is stored by the thread performing the KVM_RUN IOCTL. > > If the vCPU is already stopped, the status is stored immediately. > > Storing the status means writing into userspace, which might fault, and > __inject_sigp_stop() is called from do_inject_vcpu() which in turn is > always called holding a spinlock, which is obviously an issue. > > Fix this by returning -EWOULDBLOCK from __inject_sigp_stop(), and > adding a bool flag to indicate whether a store status is needed. The > callers of do_inject_vcpu() are modified to pass the pointer to the > bool flag; whenever a Store Status operation is needed, the callers can > now perform it outside the spinlock. > > Opportunistically refactor kvm_s390_set_irq_state() to use > scoped_guard() and __free(). > > Signed-off-by: Claudio Imbrenda > --- > arch/s390/kvm/interrupt.c | 70 +++++++++++++++++++++------------------ > 1 file changed, 38 insertions(+), 32 deletions(-) > > diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c > index 8e4b88bce31f..6940f4d354e5 100644 [...] > @@ -3188,31 +3192,33 @@ int kvm_s390_set_irq_state(struct kvm_vcpu *vcpu,= void __user *irqstate, int len > if (!buf) > return -ENOMEM; > =20 > - if (copy_from_user((void *) buf, irqstate, len)) { > - r =3D -EFAULT; > - goto out_free; > - } > + if (copy_from_user((void *)buf, irqstate, len)) > + return -EFAULT; > =20 > - /* > - * Don't allow setting the interrupt state > - * when there are already interrupts pending > - */ > - spin_lock(&li->lock); > - if (li->pending_irqs) { > - r =3D -EBUSY; > - goto out_unlock; > - } > + scoped_guard(spinlock, &li->lock) { > + /* > + * Don't allow setting the interrupt state > + * when there are already interrupts pending > + */ > + if (li->pending_irqs) > + return -EBUSY; > =20 > - for (n =3D 0; n < len / sizeof(*buf); n++) { > - r =3D do_inject_vcpu(vcpu, &buf[n]); > - if (r) > - break; > + for (n =3D 0; n < len / sizeof(*buf); n++) { > + tmp =3D false; > + r =3D do_inject_vcpu(vcpu, &buf[n], &tmp); > + if (r =3D=3D -EWOULDBLOCK && tmp) { > + storestatus =3D true; > + r =3D 0; > + } > + if (r) > + break; > + } > } > =20 > -out_unlock: > - spin_unlock(&li->lock); > -out_free: > - vfree(buf); > + if (storestatus) { > + n =3D kvm_s390_store_status_unloaded(vcpu, KVM_S390_STORE_STATUS_NOADD= R); I assume we do not care about loosing n =3D -EFAULT when we are already on = the error path here with r !=3D 0. But are there cases in which we would not wa= nt to call kvm_s390_store_status_unloaded() at all here when one of the later do_inject_vcpu() calls failed with a specific error? > + return r ? r : n; > + } > =20 > return r; > }