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Fri, 7 Apr 2023 09:31:51 +0000 (GMT) Received: from smtpav06.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 429FF20040; Fri, 7 Apr 2023 09:31:50 +0000 (GMT) Received: from r223l.aus.stglabs.ibm.com (unknown [9.3.109.14]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 7 Apr 2023 09:31:50 +0000 (GMT) From: Kautuk Consul To: Michael Ellerman , Nicholas Piggin , Christophe Leroy , Fabiano Rosas , Paolo Bonzini , Chao Peng , Sean Christopherson Subject: [PATCH] KVM: PPC: BOOK3S: book3s_hv_nested.c: improve branch prediction for k.alloc Date: Fri, 7 Apr 2023 05:31:47 -0400 Message-Id: <20230407093147.3646597-1-kconsul@linux.vnet.ibm.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 4ZX3ELC14ZsoMEP1vDLm98ZtYz6ZrGba X-Proofpoint-ORIG-GUID: Fa8FAEec0Xy9rlrTrcIHqtEQ19diXjYX X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-04-07_05,2023-04-06_03,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 phishscore=0 impostorscore=0 malwarescore=0 bulkscore=0 mlxlogscore=999 spamscore=0 suspectscore=0 lowpriorityscore=0 priorityscore=1501 clxscore=1011 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2303200000 definitions=main-2304070084 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Kautuk Consul Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" I used the unlikely() macro on the return values of the k.alloc calls and found that it changes the code generation a bit. Optimize all return paths of k.alloc calls by improving branch prediction on return value of k.alloc. Signed-off-by: Kautuk Consul --- arch/powerpc/kvm/book3s_hv_nested.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 5a64a1341e6f..dbf2dd073e1f 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -446,7 +446,7 @@ long kvmhv_nested_init(void) ptb_order = 12; pseries_partition_tb = kmalloc(sizeof(struct patb_entry) << ptb_order, GFP_KERNEL); - if (!pseries_partition_tb) { + if (unlikely(!pseries_partition_tb)) { pr_err("kvm-hv: failed to allocated nested partition table\n"); return -ENOMEM; } @@ -575,7 +575,7 @@ long kvmhv_copy_tofrom_guest_nested(struct kvm_vcpu *vcpu) return H_PARAMETER; buf = kzalloc(n, GFP_KERNEL | __GFP_NOWARN); - if (!buf) + if (unlikely(!buf)) return H_NO_MEM; gp = kvmhv_get_nested(vcpu->kvm, l1_lpid, false); @@ -689,7 +689,7 @@ static struct kvm_nested_guest *kvmhv_alloc_nested(struct kvm *kvm, unsigned int long shadow_lpid; gp = kzalloc(sizeof(*gp), GFP_KERNEL); - if (!gp) + if (unlikely(!gp)) return NULL; gp->l1_host = kvm; gp->l1_lpid = lpid; @@ -1633,7 +1633,7 @@ static long int __kvmhv_nested_page_fault(struct kvm_vcpu *vcpu, /* 4. Insert the pte into our shadow_pgtable */ n_rmap = kzalloc(sizeof(*n_rmap), GFP_KERNEL); - if (!n_rmap) + if (unlikely(!n_rmap)) return RESUME_GUEST; /* Let the guest try again */ n_rmap->rmap = (n_gpa & RMAP_NESTED_GPA_MASK) | (((unsigned long) gp->l1_lpid) << RMAP_NESTED_LPID_SHIFT);