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Thu, 22 May 2025 13:08:02 +0000 (GMT) Precedence: bulk X-Mailing-List: linux-s390@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: Thu, 22 May 2025 15:07:57 +0200 Message-Id: From: "Christoph Schlameuss" Cc: , , , , , , , , , , , To: "Claudio Imbrenda" , Subject: Re: [PATCH v2 2/5] KVM: s390: remove unneeded srcu lock X-Mailer: aerc 0.20.1 References: <20250520182639.80013-1-imbrenda@linux.ibm.com> <20250520182639.80013-3-imbrenda@linux.ibm.com> In-Reply-To: <20250520182639.80013-3-imbrenda@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTIyMDEzMyBTYWx0ZWRfX8RciIEJAVdcM jMk7926/rddypM652bWrONWZI05gd9FB/4UCm0TduLeA45f5noznWDxZ+0949iwyiEDq6R9n19P O3eXejr/SudPd6MBVUq/amFTGysmy/od4Azn1AES2l6VoLqyR9W4oLr03GpAhCH6XG/ECzTMZ0h i6Epqq702DMAi4gG3D9PwNJU9ilYk5F1CfhQRYAvdRzPyM+q6qKKsGTg6TC3GLeUJUxZPrsh34a jJLTqTTylvINkObYHl5kPmwb1bowu+LlLp4IduCjcsdKZ0FDRWfG/pozYmwq+EhNzCeWfJzOY7l 28vzKXX+9ztqkk9jLfDkgL6ysJGQCiYWf73EEMY6op/qw9CbbN4xUK5/JKLlfNem2x7QS4kvoUo Xya+zSRr/6RZ26oJiVxraf7JpNR2r330EBVOCUe1wU1uFfMNRENiuYP968tpCzTM1q3pqanw X-Proofpoint-GUID: pl2oOFwhwFTXyeF_GMPGb6uNOm0t2Yk9 X-Proofpoint-ORIG-GUID: pl2oOFwhwFTXyeF_GMPGb6uNOm0t2Yk9 X-Authority-Analysis: v=2.4 cv=EdfIQOmC c=1 sm=1 tr=0 ts=682f21b6 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=dt9VzEwgFbYA:10 a=VnNF1IyMAAAA:8 a=oh86K7MTI85CMi4h8AQA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.0.736,FMLib:17.12.80.40 definitions=2025-05-22_06,2025-05-22_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 adultscore=0 mlxscore=0 lowpriorityscore=0 malwarescore=0 phishscore=0 priorityscore=1501 bulkscore=0 clxscore=1015 mlxlogscore=806 spamscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505160000 definitions=main-2505220133 On Tue May 20, 2025 at 8:26 PM CEST, Claudio Imbrenda wrote: > All paths leading to handle_essa() already hold the kvm->srcu. > Remove unneeded srcu locking from handle_essa(). > Add lockdep assertion to make sure we will always be holding kvm->srcu > when entering handle_essa(). > > Signed-off-by: Claudio Imbrenda > Reviewed-by: Nina Schoetterl-Glausch > Reviewed-by: Christian Borntraeger Reviewed-by: Christoph Schlameuss > --- > arch/s390/kvm/priv.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c > index 1a49b89706f8..9253c70897a8 100644 > --- a/arch/s390/kvm/priv.c > +++ b/arch/s390/kvm/priv.c > @@ -1248,6 +1248,8 @@ static inline int __do_essa(struct kvm_vcpu *vcpu, = const int orc) > =20 > static int handle_essa(struct kvm_vcpu *vcpu) > { > + lockdep_assert_held(&vcpu->kvm->srcu); > + > /* entries expected to be 1FF */ > int entries =3D (vcpu->arch.sie_block->cbrlo & ~PAGE_MASK) >> 3; > unsigned long *cbrlo; > @@ -1297,12 +1299,8 @@ static int handle_essa(struct kvm_vcpu *vcpu) > /* Retry the ESSA instruction */ > kvm_s390_retry_instr(vcpu); > } else { > - int srcu_idx; > - > mmap_read_lock(vcpu->kvm->mm); > - srcu_idx =3D srcu_read_lock(&vcpu->kvm->srcu); > i =3D __do_essa(vcpu, orc); > - srcu_read_unlock(&vcpu->kvm->srcu, srcu_idx); > mmap_read_unlock(vcpu->kvm->mm); > if (i < 0) > return i;