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Mon, 23 Mar 2026 11:10:35 +0000 (GMT) Date: Mon, 23 Mar 2026 12:10:33 +0100 From: Steffen Eiden To: Claudio Imbrenda Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, borntraeger@de.ibm.com, frankja@linux.ibm.com, nrb@linux.ibm.com, gra@linux.ibm.com, schlameuss@linux.ibm.com, hca@linux.ibm.com, david@kernel.org Subject: Re: [PATCH v2 8/8] KVM: s390: Fix KVM_S390_VCPU_FAULT ioctl Message-ID: <20260323111033.66303-F-seiden@linux.ibm.com> References: <20260320161542.202913-1-imbrenda@linux.ibm.com> <20260320161542.202913-9-imbrenda@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260320161542.202913-9-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=IqITsb/g c=1 sm=1 tr=0 ts=69c11fb0 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=kj9zAlcOel0A:10 a=Yq5XynenixoA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=qADLU7ugqkt86NIBnJAA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMzIzMDA4MyBTYWx0ZWRfX0v5TnTDsIF9e miBChkV4S/WrvWvLq0jlINRwCXd44DzMxVCg3d0zTk/QTml/YVVCm2KbvFeAJatkOT+r1NroSI1 7vD3oaRZay/CmyGCvB3SVUs398j8J22fmny0QZQi62kDW7cnL+l+88fFYzOVX+/lDVRWrpXnrIv MVpEf0FofY+GQG1rFxmkhI74lvbZo+JuttUnny0xEwsdPN3RX6G3D2rcJAH/bfuKCsniLIHsh1j iE9TvEIbkzuhPkgXDw+1UWXeVPRLhVHuiCbjqteFvfexL1XoD/Rrq/J3IYvf+N2W1yJN41wQWHi 7+nxfNoDFcRPRWeJ00qRTPpnGWXdU3xb14rO46BZTYLVt/DR9xzzDq1W58EfwaCActNz1oNNsbs Z/PU++eDOCuskI3r9iioni9URx6JjI11D8x+dgzLAPVuGkY5d/eqZKaHp+Csb00LyUJhjFaxQqd YAKD6TeQaPSdgsVkxew== X-Proofpoint-GUID: AWTw3O-3Bqf-6dIaOv0cC18j2a6FyK6J X-Proofpoint-ORIG-GUID: AWTw3O-3Bqf-6dIaOv0cC18j2a6FyK6J 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=2026-03-23_03,2026-03-20_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 clxscore=1015 spamscore=0 impostorscore=0 suspectscore=0 phishscore=0 bulkscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2603050001 definitions=main-2603230083 On Fri, Mar 20, 2026 at 05:15:42PM +0100, Claudio Imbrenda wrote: > A previous commit changed the behaviour of the KVM_S390_VCPU_FAULT > ioctl. The current (wrong) implementation will trigger a guest > addressing exception if the requested address lies outside of a > memslot, unless the VM is UCONTROL. > > Restore the previous behaviour by open coding the fault-in logic. > > Fixes: 3762e905ec2e ("KVM: s390: use __kvm_faultin_pfn()") > Signed-off-by: Claudio Imbrenda Reviewed-by: Steffen Eiden But I have a comment on a changed logic. And a nit > --- > arch/s390/kvm/kvm-s390.c | 18 +++++++++++++++--- > 1 file changed, 15 insertions(+), 3 deletions(-) > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index ebcb0ef8835e..62f04931b54d 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -5520,9 +5520,21 @@ long kvm_arch_vcpu_ioctl(struct file *filp, > } > #endif > case KVM_S390_VCPU_FAULT: { > - idx = srcu_read_lock(&vcpu->kvm->srcu); > - r = vcpu_dat_fault_handler(vcpu, arg, 0); in here every vcpu_ucontrol_translate error (incl ENONEMs from kvm_s390_mmu_cache_topup) is converted into EREMOTE ... > - srcu_read_unlock(&vcpu->kvm->srcu, idx); > + gpa_t gaddr = arg; > + > + scoped_guard(srcu, &vcpu->kvm->srcu) { > + r = vcpu_ucontrol_translate(vcpu, &gaddr); > + if (r) > + break; ... which is not longer the case here. As you explicitly convert ENOMENS in gmap_ucas_translate before the topup call tnot converting might be an overlook (in the topup function?). > + > + r = kvm_s390_faultin_gfn_simple(vcpu, NULL, gpa_to_gfn(gaddr), false); > + if (r == PGM_ADDRESSING) > + r = -EFAULT; > + if (r <= 0) > + break; nit: in vcpu_dat_fault_handler the ifs are in the inverse order. They are independent, so this does not make any difference, but this itches me a little. :) > + r = -EIO; > + KVM_BUG_ON(r, vcpu->kvm); > + } > break; > } > case KVM_ENABLE_CAP: > -- > 2.53.0 > Steffen