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Sat, 11 Jul 2020 09:14:03 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D9C5D11C04A; Sat, 11 Jul 2020 09:14:00 +0000 (GMT) Received: from oc0525413822.ibm.com (unknown [9.163.39.1]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Sat, 11 Jul 2020 09:14:00 +0000 (GMT) From: Ram Pai To: kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [v3 1/5] KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START Date: Sat, 11 Jul 2020 02:13:43 -0700 Message-Id: <1594458827-31866-2-git-send-email-linuxram@us.ibm.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1594458827-31866-1-git-send-email-linuxram@us.ibm.com> References: <1594458827-31866-1-git-send-email-linuxram@us.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-07-11_03:2020-07-10, 2020-07-11 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 clxscore=1015 suspectscore=2 phishscore=0 priorityscore=1501 bulkscore=0 malwarescore=0 mlxscore=0 mlxlogscore=721 spamscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2007110065 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: ldufour@linux.ibm.com, linuxram@us.ibm.com, cclaudio@linux.ibm.com, bharata@linux.ibm.com, sathnaga@linux.vnet.ibm.com, aneesh.kumar@linux.ibm.com, sukadev@linux.vnet.ibm.com, bauerman@linux.ibm.com, david@gibson.dropbear.id.au Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Merging of pages associated with each memslot of a SVM is disabled the page is migrated in H_SVM_PAGE_IN handler. This operation should have been done much earlier; the moment the VM is initiated for secure-transition. Delaying this operation, increases the probability for those pages to acquire new references , making it impossible to migrate those pages in H_SVM_PAGE_IN handler. Disable page-migration in H_SVM_INIT_START handling. Signed-off-by: Ram Pai --- arch/powerpc/kvm/book3s_hv_uvmem.c | 96 +++++++++++++++++++++++++++++--------- 1 file changed, 74 insertions(+), 22 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 3d987b1..bfc3841 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -211,6 +211,65 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm, return false; } +static int kvmppc_memslot_page_merge(struct kvm *kvm, + struct kvm_memory_slot *memslot, bool merge) +{ + unsigned long gfn = memslot->base_gfn; + unsigned long end, start = gfn_to_hva(kvm, gfn); + int ret = 0; + struct vm_area_struct *vma; + int merge_flag = (merge) ? MADV_MERGEABLE : MADV_UNMERGEABLE; + + if (kvm_is_error_hva(start)) + return H_STATE; + + end = start + (memslot->npages << PAGE_SHIFT); + + down_write(&kvm->mm->mmap_sem); + do { + vma = find_vma_intersection(kvm->mm, start, end); + if (!vma) { + ret = H_STATE; + break; + } + ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, + merge_flag, &vma->vm_flags); + if (ret) { + ret = H_STATE; + break; + } + start = vma->vm_end + 1; + } while (end > vma->vm_end); + + up_write(&kvm->mm->mmap_sem); + return ret; +} + +static int __kvmppc_page_merge(struct kvm *kvm, bool merge) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *memslot; + int ret = 0; + + slots = kvm_memslots(kvm); + kvm_for_each_memslot(memslot, slots) { + ret = kvmppc_memslot_page_merge(kvm, memslot, merge); + if (ret) + break; + } + return ret; +} + +static inline int kvmppc_disable_page_merge(struct kvm *kvm) +{ + return __kvmppc_page_merge(kvm, false); +} + +static inline int kvmppc_enable_page_merge(struct kvm *kvm) +{ + return __kvmppc_page_merge(kvm, true); +} + unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) { struct kvm_memslots *slots; @@ -232,11 +291,18 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) return H_AUTHORITY; srcu_idx = srcu_read_lock(&kvm->srcu); + + /* disable page-merging for all memslot */ + ret = kvmppc_disable_page_merge(kvm); + if (ret) + goto out; + + /* register the memslot */ slots = kvm_memslots(kvm); kvm_for_each_memslot(memslot, slots) { if (kvmppc_uvmem_slot_init(kvm, memslot)) { ret = H_PARAMETER; - goto out; + break; } ret = uv_register_mem_slot(kvm->arch.lpid, memslot->base_gfn << PAGE_SHIFT, @@ -245,9 +311,12 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) if (ret < 0) { kvmppc_uvmem_slot_free(kvm, memslot); ret = H_PARAMETER; - goto out; + break; } } + + if (ret) + kvmppc_enable_page_merge(kvm); out: srcu_read_unlock(&kvm->srcu, srcu_idx); return ret; @@ -384,7 +453,7 @@ static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm) */ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, unsigned long end, unsigned long gpa, struct kvm *kvm, - unsigned long page_shift, bool *downgrade) + unsigned long page_shift) { unsigned long src_pfn, dst_pfn = 0; struct migrate_vma mig; @@ -400,18 +469,6 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, mig.src = &src_pfn; mig.dst = &dst_pfn; - /* - * We come here with mmap_sem write lock held just for - * ksm_madvise(), otherwise we only need read mmap_sem. - * Hence downgrade to read lock once ksm_madvise() is done. - */ - ret = ksm_madvise(vma, vma->vm_start, vma->vm_end, - MADV_UNMERGEABLE, &vma->vm_flags); - downgrade_write(&kvm->mm->mmap_sem); - *downgrade = true; - if (ret) - return ret; - ret = migrate_vma_setup(&mig); if (ret) return ret; @@ -503,7 +560,6 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, unsigned long flags, unsigned long page_shift) { - bool downgrade = false; unsigned long start, end; struct vm_area_struct *vma; int srcu_idx; @@ -540,16 +596,12 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, if (!vma || vma->vm_start > start || vma->vm_end < end) goto out_unlock; - if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift, - &downgrade)) + if (!kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift)) ret = H_SUCCESS; out_unlock: mutex_unlock(&kvm->arch.uvmem_lock); out: - if (downgrade) - up_read(&kvm->mm->mmap_sem); - else - up_write(&kvm->mm->mmap_sem); + up_write(&kvm->mm->mmap_sem); srcu_read_unlock(&kvm->srcu, srcu_idx); return ret; } -- 1.8.3.1