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Thu, 30 Jul 2026 09:14:08 +0000 (GMT) Received: from p-imbrenda (unknown [9.111.80.248]) by smtpav01.fra02v.mail.ibm.com (Postfix) with SMTP; Thu, 30 Jul 2026 09:14:08 +0000 (GMT) Date: Thu, 30 Jul 2026 10:51:21 +0200 From: Claudio Imbrenda To: Heiko Carstens Cc: Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger , Harald Freudenberger , Holger Dengler , Vineeth Vijayan , Peter Oberparleiter , Janosch Frank , David Hildenbrand , Peter Zijlstra , Herbert Xu , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: Re: [PATCH v3 2/4] KVM: s390: Remove cond_resched() calls Message-ID: <20260730105121.3dd5c400@p-imbrenda> In-Reply-To: <20260730052907.2607026-3-hca@linux.ibm.com> References: <20260730052907.2607026-1-hca@linux.ibm.com> <20260730052907.2607026-3-hca@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: linux-crypto@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-ORIG-GUID: uGeCF_RT_7fgEu9JL2akTQK933OobWQ- X-Proofpoint-Spam-Info: AW1haW4tMjYwNzMwMDA2MyBTYWx0ZWRfXwr/aYuy3i5ve vikcAWZjSJev27ieTiDv2WEi3tpIOKyz//zTmv+H1WOIuEbBsqd4nX45hpABSx52O1XGS8H/uie g9BDt6aA3GdejG36qwISEXr9Iimvhd0= X-Authority-Analysis: v=2.4 cv=E/z9Y6dl c=1 sm=1 tr=0 ts=6a6b15e6 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=kj9zAlcOel0A:10 a=RAioF0-LDSMA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=ne4xOJbHfJve2HjgNyoA:9 a=CjuIK1q_8ugA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzMwMDA2MyBTYWx0ZWRfX24NmTInUFNpv 9COLkUrVuVKS44onZc/UKYlH/+YCn5Jg8Jp4gMNuN3mX1RHoRDODerbh2VNGg18pw4hYIOLzzWA M53a4KiSUwhInUZ9Ws5NXarDKaPN+DQCgtnDv2AODovdxEGlBE81l2OQjF/nIC2tKTDZFPXj3rf SrbyHtp7zpWzozlW0jxS2eiRXsYZZXx9bl4iyJIs1hzpJK0AEyyq7N3YzS7WG4+6o7by7ljXvZC RzggCQt2FIXah0JcpEgbcHDd0oh3EfiliKVgA6pDXzrWYmjBiolTi78E5P33IKDHiG/aX9Vuvnc Q2eboenap9HmvGEqrdp7qG22PnA1hDUmoGLx/JBsO3gKS//8QQ+74mAptbfG07HQTgPTYbMj4Oh EGQhSI3CpcR/iFghmAW5jgD0EiaBqIaXEMgT+/S5B8UwX7LJi1XdIJ4A8cVQus8yI9vgEBNr+yY jWxpdQBTUFQ2vjeFJRQ== X-Proofpoint-GUID: uGeCF_RT_7fgEu9JL2akTQK933OobWQ- X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-30_02,2026-07-29_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 priorityscore=1501 spamscore=0 clxscore=1011 phishscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607300063 On Thu, 30 Jul 2026 07:29:05 +0200 Heiko Carstens wrote: > Since [1] cond_resched() is a no-op on s390. Remove all calls. > > This also entirely removes uv_call_sched() and replaces all call sites > with uv_call(), since both functions are identical after the removal > of cond_resched(). > > [1] commit 7dadeaa6e851 ("sched: Further restrict the preemption modes") > > Signed-off-by: Heiko Carstens Reviewed-by: Claudio Imbrenda > --- > arch/s390/include/asm/uv.h | 16 ++-------------- > arch/s390/kernel/uv.c | 2 +- > arch/s390/kvm/gaccess.c | 8 ++------ > arch/s390/kvm/gmap.c | 4 ---- > arch/s390/kvm/kvm-s390.c | 1 - > arch/s390/kvm/pv.c | 11 +++++------ > arch/s390/kvm/vsie.c | 1 - > arch/s390/mm/gmap_helpers.c | 1 - > drivers/s390/char/uvdevice.c | 6 +++--- > 9 files changed, 13 insertions(+), 37 deletions(-) > > diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h > index d919e69662f5..89c9bb56c7e6 100644 > --- a/arch/s390/include/asm/uv.h > +++ b/arch/s390/include/asm/uv.h > @@ -454,18 +454,6 @@ static inline int uv_call(unsigned long r1, unsigned long r2) > return cc; > } > > -/* Low level uv_call that avoids stalls for long running busy conditions */ > -static inline int uv_call_sched(unsigned long r1, unsigned long r2) > -{ > - int cc; > - > - do { > - cc = __uv_call(r1, r2); > - cond_resched(); > - } while (cc > 1); > - return cc; > -} > - > /* > * special variant of uv_call that only transports the cpu or guest > * handle and the command, like destroy or verify. > @@ -480,7 +468,7 @@ static inline int uv_cmd_nodata(u64 handle, u16 cmd, u16 *rc, u16 *rrc) > int cc; > > WARN(!handle, "No handle provided to Ultravisor call cmd %x\n", cmd); > - cc = uv_call_sched(0, (u64)&uvcb); > + cc = uv_call(0, (u64)&uvcb); > *rc = uvcb.header.rc; > *rrc = uvcb.header.rrc; > return cc ? -EINVAL : 0; > @@ -518,7 +506,7 @@ static inline int uv_list_secrets(struct uv_secret_list *buf, u16 start_idx, > .start_idx = start_idx, > .list_addr = (u64)buf, > }; > - int cc = uv_call_sched(0, (u64)&uvcb); > + int cc = uv_call(0, (u64)&uvcb); > > if (rc) > *rc = uvcb.header.rc; > diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c > index a284f98d9716..62841bb00a26 100644 > --- a/arch/s390/kernel/uv.c > +++ b/arch/s390/kernel/uv.c > @@ -831,7 +831,7 @@ int uv_retrieve_secret(u16 secret_idx, u8 *buf, size_t buf_size) > .buf_size = buf_size, > }; > > - uv_call_sched(0, (u64)&uvcb); > + uv_call(0, (u64)&uvcb); > > switch (uvcb.header.rc) { > case UVC_RC_EXECUTED: > diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c > index 36102b2727fb..0d389a302a70 100644 > --- a/arch/s390/kvm/gaccess.c > +++ b/arch/s390/kvm/gaccess.c > @@ -151,10 +151,8 @@ static void ipte_lock_simple(struct kvm *kvm) > ic = &kvm->arch.sca->ipte_control; > old = READ_ONCE(*ic); > do { > - if (old.k) { > - cond_resched(); > + if (old.k) > goto retry; > - } > new = old; > new.k = 1; > } while (!try_cmpxchg(&ic->val, &old.val, new.val)); > @@ -189,10 +187,8 @@ static void ipte_lock_siif(struct kvm *kvm) > ic = &kvm->arch.sca->ipte_control; > old = READ_ONCE(*ic); > do { > - if (old.kg) { > - cond_resched(); > + if (old.kg) > goto retry; > - } > new = old; > new.k = 1; > new.kh++; > diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c > index 8abb4f55b306..3758e4009709 100644 > --- a/arch/s390/kvm/gmap.c > +++ b/arch/s390/kvm/gmap.c > @@ -941,7 +941,6 @@ void gmap_split_huge_pages(struct gmap *gmap) > scoped_guard(read_lock, &gmap->kvm->mmu_lock) > start = _dat_walk_gfn_range(start, asce_end(gmap->asce), gmap->asce, > &ops, DAT_WALK_IGN_HOLES, gmap); > - cond_resched(); > } while (start); > } > > @@ -963,7 +962,6 @@ static int _gmap_enable_skeys(struct gmap *gmap) > do { > scoped_guard(write_lock, &gmap->kvm->mmu_lock) > start = dat_reset_skeys(gmap->asce, start); > - cond_resched(); > } while (start); > return 0; > } > @@ -1019,7 +1017,6 @@ int gmap_pv_destroy_range(struct gmap *gmap, gfn_t start, gfn_t end, bool interr > DAT_WALK_IGN_HOLES, NULL); > if (interruptible && fatal_signal_pending(current)) > return -EINTR; > - cond_resched(); > } while (start && start < end); > return 0; > } > @@ -1138,7 +1135,6 @@ void _gmap_set_cmma_all(struct gmap *gmap, bool dirty) > gfn = _dat_walk_gfn_range(gfn, asce_end(gmap->asce), gmap->asce, &ops, > DAT_WALK_IGN_HOLES, > &gmap->kvm->arch.cmma_dirty_pages); > - cond_resched(); > } while (gfn); > } > > diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c > index 150b5dd2170e..2ede8f035a38 100644 > --- a/arch/s390/kvm/kvm-s390.c > +++ b/arch/s390/kvm/kvm-s390.c > @@ -1027,7 +1027,6 @@ static int kvm_s390_set_mem_control(struct kvm *kvm, struct kvm_device_attr *att > do { > scoped_guard(read_lock, &kvm->mmu_lock) > start_gfn = dat_reset_cmma(kvm->arch.gmap->asce, start_gfn); > - cond_resched(); > } while (start_gfn); > ret = 0; > break; > diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c > index 1beacc841ca8..54c17ddb6b11 100644 > --- a/arch/s390/kvm/pv.c > +++ b/arch/s390/kvm/pv.c > @@ -429,7 +429,7 @@ static int kvm_s390_pv_deinit_vm_fast(struct kvm *kvm, u16 *rc, u16 *rrc) > }; > int cc; > > - cc = uv_call_sched(0, (u64)&uvcb); > + cc = uv_call(0, (u64)&uvcb); > if (rc) > *rc = uvcb.header.rc; > if (rrc) > @@ -746,7 +746,7 @@ int kvm_s390_pv_init_vm(struct kvm *kvm, u16 *rc, u16 *rrc) > } > gmap_split_huge_pages(kvm->arch.gmap); > > - cc = uv_call_sched(0, (u64)&uvcb); > + cc = uv_call(0, (u64)&uvcb); > *rc = uvcb.header.rc; > *rrc = uvcb.header.rrc; > KVM_UV_EVENT(kvm, 3, "PROTVIRT CREATE VM: handle %llx len %llx rc %x rrc %x flags %04x", > @@ -832,7 +832,6 @@ int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size, > while (offset < size) { > ret = unpack_one(kvm, addr, tweak, offset, rc, rrc); > if (ret == -EAGAIN) { > - cond_resched(); > if (fatal_signal_pending(current)) > break; > continue; > @@ -875,7 +874,7 @@ int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc) > }; > int cc; > > - cc = uv_call_sched(0, (u64)&uvcb); > + cc = uv_call(0, (u64)&uvcb); > *rc = uvcb.header.rc; > *rrc = uvcb.header.rrc; > return cc; > @@ -959,7 +958,7 @@ int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user, > /* We will loop until the user buffer is filled or an error occurs */ > do { > /* Get 1MB worth of guest storage state data */ > - cc = uv_call_sched(0, (u64)&uvcb); > + cc = uv_call(0, (u64)&uvcb); > > /* All or nothing */ > if (cc) { > @@ -1037,7 +1036,7 @@ int kvm_s390_pv_dump_complete(struct kvm *kvm, void __user *buff_user, > return -ENOMEM; > complete.dump_area_origin = (u64)compl_data; > > - ret = uv_call_sched(0, (u64)&complete); > + ret = uv_call(0, (u64)&complete); > *rc = complete.header.rc; > *rrc = complete.header.rrc; > KVM_UV_EVENT(kvm, 3, "PROTVIRT DUMP COMPLETE: rc %x rrc %x", > diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c > index eea24562e7db..6dcd3b110c17 100644 > --- a/arch/s390/kvm/vsie.c > +++ b/arch/s390/kvm/vsie.c > @@ -1434,7 +1434,6 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page) > } > if (sg) > sg = gmap_put(sg); > - cond_resched(); > } > if (sg) > sg = gmap_put(sg); > diff --git a/arch/s390/mm/gmap_helpers.c b/arch/s390/mm/gmap_helpers.c > index 4bf7c9012feb..d564cdefb90f 100644 > --- a/arch/s390/mm/gmap_helpers.c > +++ b/arch/s390/mm/gmap_helpers.c > @@ -272,7 +272,6 @@ static int __gmap_helper_unshare_zeropages(struct mm_struct *mm) > * truncation. In that case, the shared zeropage would be gone > * and we can simply retry and make progress. > */ > - cond_resched(); > goto retry; > } > > diff --git a/drivers/s390/char/uvdevice.c b/drivers/s390/char/uvdevice.c > index e6a264c996ce..4d274a2ee84d 100644 > --- a/drivers/s390/char/uvdevice.c > +++ b/drivers/s390/char/uvdevice.c > @@ -224,7 +224,7 @@ static int uvio_attestation(struct uvio_ioctl_cb *uv_ioctl) > if (ret) > goto out; > > - uv_call_sched(0, (u64)uvcb_attest); > + uv_call(0, (u64)uvcb_attest); > > uv_ioctl->uv_rc = uvcb_attest->header.rc; > uv_ioctl->uv_rrc = uvcb_attest->header.rrc; > @@ -291,7 +291,7 @@ static int uvio_add_secret(struct uvio_ioctl_cb *uv_ioctl) > > ret = 0; > uvcb.addr = (u64)asrcb; > - uv_call_sched(0, (u64)&uvcb); > + uv_call(0, (u64)&uvcb); > uv_ioctl->uv_rc = uvcb.header.rc; > uv_ioctl->uv_rrc = uvcb.header.rrc; > > @@ -457,7 +457,7 @@ static int uvio_retr_secret(struct uvio_ioctl_cb *uv_ioctl) > > uvcb.buf_addr = (u64)buf; > uvcb.buf_size = buf_len; > - uv_call_sched(0, (u64)&uvcb); > + uv_call(0, (u64)&uvcb); > > if (copy_to_user((__user void *)uv_ioctl->argument_addr, buf, buf_len)) > goto err;