From 2027a24a75ce32cf48a22cc25a9d87b8c5b19328 Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Mon, 27 Jul 2020 11:07:15 -0700 Subject: KVM: PPC: Book3S HV: Disable page merging in H_SVM_INIT_START Page-merging of pages in memory-slots associated with a Secure VM is disabled in H_SVM_PAGE_IN handler. This operation should have been done the 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. Reviewed-by: Bharata B Rao Signed-off-by: Ram Pai Signed-off-by: Paul Mackerras --- Documentation/powerpc/ultravisor.rst | 1 + arch/powerpc/kvm/book3s_hv_uvmem.c | 123 +++++++++++++++++++++++++---------- 2 files changed, 89 insertions(+), 35 deletions(-) diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst index df136c8f91fa..a1c8c37159a1 100644 --- a/Documentation/powerpc/ultravisor.rst +++ b/Documentation/powerpc/ultravisor.rst @@ -895,6 +895,7 @@ Return values One of the following values: * H_SUCCESS on success. + * H_STATE if the VM is not in a position to switch to secure. Description ~~~~~~~~~~~ diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index e6f76bc16d04..533b608c8d20 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -211,10 +211,79 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm, return false; } +static int kvmppc_memslot_page_merge(struct kvm *kvm, + const 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); + + mmap_write_lock(kvm->mm); + 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; + } while (end > vma->vm_end); + + mmap_write_unlock(kvm->mm); + return ret; +} + +static void kvmppc_uvmem_memslot_delete(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + uv_unregister_mem_slot(kvm->arch.lpid, memslot->id); + kvmppc_uvmem_slot_free(kvm, memslot); + kvmppc_memslot_page_merge(kvm, memslot, true); +} + +static int kvmppc_uvmem_memslot_create(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + int ret = H_PARAMETER; + + if (kvmppc_memslot_page_merge(kvm, memslot, false)) + return ret; + + if (kvmppc_uvmem_slot_init(kvm, memslot)) + goto out1; + + ret = uv_register_mem_slot(kvm->arch.lpid, + memslot->base_gfn << PAGE_SHIFT, + memslot->npages * PAGE_SIZE, + 0, memslot->id); + if (ret < 0) { + ret = H_PARAMETER; + goto out; + } + return 0; +out: + kvmppc_uvmem_slot_free(kvm, memslot); +out1: + kvmppc_memslot_page_merge(kvm, memslot, true); + return ret; +} + unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) { struct kvm_memslots *slots; - struct kvm_memory_slot *memslot; + struct kvm_memory_slot *memslot, *m; int ret = H_SUCCESS; int srcu_idx; @@ -232,23 +301,24 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) return H_AUTHORITY; srcu_idx = srcu_read_lock(&kvm->srcu); + + /* 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; - } - ret = uv_register_mem_slot(kvm->arch.lpid, - memslot->base_gfn << PAGE_SHIFT, - memslot->npages * PAGE_SIZE, - 0, memslot->id); - if (ret < 0) { - kvmppc_uvmem_slot_free(kvm, memslot); - ret = H_PARAMETER; - goto out; + ret = kvmppc_uvmem_memslot_create(kvm, memslot); + if (ret) + break; + } + + if (ret) { + slots = kvm_memslots(kvm); + kvm_for_each_memslot(m, slots) { + if (m == memslot) + break; + kvmppc_uvmem_memslot_delete(kvm, memslot); } } -out: + srcu_read_unlock(&kvm->srcu, srcu_idx); return ret; } @@ -384,7 +454,7 @@ out: */ 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 +470,6 @@ 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_lock write lock held just for - * ksm_madvise(), otherwise we only need read mmap_lock. - * 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); - mmap_write_downgrade(kvm->mm); - *downgrade = true; - if (ret) - return ret; - ret = migrate_vma_setup(&mig); if (ret) return ret; @@ -503,7 +561,6 @@ 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; @@ -524,7 +581,7 @@ unsigned long kvmppc_h_svm_page_in(struct kvm *kvm, unsigned long gpa, ret = H_PARAMETER; srcu_idx = srcu_read_lock(&kvm->srcu); - mmap_write_lock(kvm->mm); + mmap_read_lock(kvm->mm); start = gfn_to_hva(kvm, gfn); if (kvm_is_error_hva(start)) @@ -540,16 +597,12 @@ 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) - mmap_read_unlock(kvm->mm); - else - mmap_write_unlock(kvm->mm); + mmap_read_unlock(kvm->mm); srcu_read_unlock(&kvm->srcu, srcu_idx); return ret; } -- cgit