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Thu, 22 May 2025 13:23:00 +0000 (GMT) From: Claudio Imbrenda To: linux-kernel@vger.kernel.org Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, frankja@linux.ibm.com, borntraeger@de.ibm.com, seiden@linux.ibm.com, nsg@linux.ibm.com, nrb@linux.ibm.com, david@redhat.com, hca@linux.ibm.com, agordeev@linux.ibm.com, svens@linux.ibm.com, gor@linux.ibm.com, schlameuss@linux.ibm.com Subject: [PATCH v3 2/4] KVM: s390: remove unneeded srcu lock Date: Thu, 22 May 2025 15:22:57 +0200 Message-ID: <20250522132259.167708-3-imbrenda@linux.ibm.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250522132259.167708-1-imbrenda@linux.ibm.com> References: <20250522132259.167708-1-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-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwNTIyMDEzMyBTYWx0ZWRfX4ytbLFeZjgK+ Ncs++e9nFGGS+KGPckJDiGbmT+ZYvEHTAvk5lx+vpk49Hx121tsIR1D0SdkVeADVebAFJorvXSV K2geW4HCur+64KjdgWEnPW9NloZzr6CNLPUkz/KhuJ79HwdrYu70YZVW3LBuEk0RfcoPkKVfZAT leHzpQzYCx6nuZUQ+yDwYgZkfKBjU3spWsaerDbLkyfLLR6q/XrApAlAQwpnKfCSI2DAL67ci2x Mcv3IiEtQYOeGyvuCc23GfAGy1dyFauOi9yuWa5k7BuWkFRJp2tbQrw8xOoU3+4p9hH2IryKuAZ X4/zP3GGVlv7T2+R3aIf1RuE/q2LSMk7SLMEuzxU/rMn6j/hPeWCyscggKVwHbr58rcQdzwr408 boBA79Ha+pQ3WC579BgX2stbrfeW8sNx5PLB8j4ttjFtq0nuTlRlB0Ic6gNrEVXTcNB6h/NO X-Proofpoint-GUID: Gbh2uI7HZhfy3ML-C07Wqd4_JD8aDPJX X-Proofpoint-ORIG-GUID: Gbh2uI7HZhfy3ML-C07Wqd4_JD8aDPJX X-Authority-Analysis: v=2.4 cv=HcAUTjE8 c=1 sm=1 tr=0 ts=682f2539 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=dt9VzEwgFbYA:10 a=VnNF1IyMAAAA:8 a=-g0RikXFz7zMAnJmuvsA:9 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 priorityscore=1501 bulkscore=0 mlxscore=0 suspectscore=0 adultscore=0 impostorscore=0 lowpriorityscore=0 mlxlogscore=770 malwarescore=0 spamscore=0 phishscore=0 clxscore=1015 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505160000 definitions=main-2505220133 Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Steffen Eiden --- 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, co= nst 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; --=20 2.49.0