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Tue, 11 Aug 2026 18:01:18 +0000 (GMT) Received: from p-imbrenda (unknown [9.224.75.30]) by smtpav06.fra02v.mail.ibm.com (Postfix) with SMTP; Tue, 11 Aug 2026 18:01:18 +0000 (GMT) Date: Tue, 11 Aug 2026 20:01:15 +0200 From: Claudio Imbrenda To: Christian Borntraeger Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, david@kernel.org, seiden@linux.ibm.com, nrb@linux.ibm.com, schlameuss@linux.ibm.com, gra@linux.ibm.com Subject: Re: [PATCH v1 02/11] KVM: s390: Use srcu in kvm_arch_vcpu_unlocked_ioctl() Message-ID: <20260811200115.03b66ee0@p-imbrenda> In-Reply-To: References: <20260811155641.219777-1-imbrenda@linux.ibm.com> <20260811155641.219777-3-imbrenda@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.4.0 (GTK 3.24.52; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: kvm@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-Spam-Details-Enc: AW1haW4tMjYwODExMDE1MSBTYWx0ZWRfXydz77Ab9RTQV j7WzFK2/hLSR0/G40PgYnfT4d47kzWw7qy/QopmV27/gOd8PuyXtLQZjBI8woshgjocj8MKDmvM 8BAkoX0z/XvqZmOUyXJF7ps+eV71uwfWD71Fp9079jsHASFmzsRzswJ/E63e7c2soSALyp4gzhz rMl7hILeZKWwD6uL70MhfNDfBlx8LgzE+Zqg8UHuVWlQD/ceE1LO3VZ0tXXHWBE2/zbOWrIXgkD 8Tk8EA4vhYPjP9NOHH4eWMnluD++DKf3jB3868liJIyM8edFBH5qliDRnLzMCUW24+JgvfQ0R+F zEq9T7fO1UBjvOpdF+xCwhIRTqPEgjuLTQnaMd1Xvx3B2QVl9KbCtPKO3nfruoq6Qg4jD0bp3eF EBSFDLsHDz4pQN/Jylts2ImB9rCMSejoJa6qd0fmEQI+rUc154glVSa6sglOVvpRYyUVhEaAi/m 6w4TArPMXj90lOlPeTA== X-Proofpoint-Spam-Info: AW1haW4tMjYwODExMDE1MSBTYWx0ZWRfX0Goxw5hdqR2x 9ktJ1az2BWyoXysEBUPH+dIU6d7+01eobL3UlzKwNjqNBhAFGgQrjF2dEZYBlohNsFu869mgPAl SVOmu9AKj42V6Qv4YgNdbHVeJmQPmlo= X-Authority-Analysis: v=2.4 cv=RqD16imK c=1 sm=1 tr=0 ts=6a7b6376 cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=kj9zAlcOel0A:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=VnNF1IyMAAAA:8 a=9C0cF1Sc3kSFM2HxLBEA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-GUID: DMHlLco21i1wiKRkhQhzeiwAMOUL6U3S X-Proofpoint-ORIG-GUID: DMHlLco21i1wiKRkhQhzeiwAMOUL6U3S 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=2026-08-11_04,2026-08-10_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 priorityscore=1501 suspectscore=0 lowpriorityscore=0 clxscore=1015 adultscore=0 bulkscore=0 malwarescore=0 impostorscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608110151 On Tue, 11 Aug 2026 19:26:42 +0200 Christian Borntraeger wrote: > Am 11.08.26 um 17:56 schrieb Claudio Imbrenda: > > kvm_arch_vcpu_unlocked_ioctl() is called without further locks held, but > > kvm_s390_inject_vcpu(), which is called from there, needs either the > > kvm->srcu or the slots lock. > > > > Fix by taking the kvm->srcu in kvm_arch_vcpu_unlocked_ioctl(). > > > > Fixes: ba5c1e9b6cee ("KVM: s390: interrupt subsystem, cpu timer, waitpsw") > > Signed-off-by: Claudio Imbrenda > > --- > > arch/s390/kvm/kvm-s390.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > > index 518a69c55e85..02c5428ba239 100644 > > --- a/arch/s390/kvm/kvm-s390.c > > +++ b/arch/s390/kvm/kvm-s390.c > > @@ -5444,6 +5444,8 @@ long kvm_arch_vcpu_unlocked_ioctl(struct file *filp, unsigned int ioctl, > > void __user *argp = (void __user *)arg; > > int rc; > > > > + guard(srcu)(&vcpu->kvm->srcu); > > + > > not a bug, but just having srcu around both inject would avoid having holding srcu on the > argument usercopy. This is not forbidden but might just take a while when paging. > > scoped_guard(srcu)(&vcpu->kvm->srcu) > rc = kvm_s390_inject_vcpu(vcpu, &s390irq); > > in any way, no objection to your variant and a real fix. > > Reviewed-by: Christian Borntraeger I had not considered the user copy; I will definitely respin with the scoped_guard() > > > > switch (ioctl) { > > case KVM_S390_IRQ: { > > struct kvm_s390_irq s390irq; >