| Message ID | 1594972827-13928-2-git-send-email-linuxram@us.ibm.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Migrate non-migrated pages of a SVM. | expand |
On Fri, Jul 17, 2020 at 01:00:23AM -0700, Ram Pai wrote: > 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 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. > > Disable page-migration in H_SVM_INIT_START handling. > > Signed-off-by: Ram Pai <linuxram@us.ibm.com> Reviewed-by: Bharata B Rao <bharata@linux.ibm.com> with a few observations below... > --- > Documentation/powerpc/ultravisor.rst | 1 + > arch/powerpc/kvm/book3s_hv_uvmem.c | 98 +++++++++++++++++++++++++++--------- > 2 files changed, 76 insertions(+), 23 deletions(-) > > diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst > index df136c8..a1c8c37 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 e6f76bc..0baa293 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); > + > + 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 + 1; This should be start = vma->vm_end I believe. > + } while (end > vma->vm_end); > + > + mmap_write_unlock(kvm->mm); > + 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; > +} You walk through all the slots here to issue kvm_madvise, but... > + > +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) { ... you are walking thro' the same set of slots here anyway. I think it makes sense to issue merge advices from here itself. That will help you to share code with kvmppc_memslot_create() in 5/5. All the below 3 calls are common to both the code paths, I think they can be carved out into a separate function if you prefer. kvmppc_uvmem_slot_init kvmppc_memslot_page_merge uv_register_mem_slot Regards, Bharata.
diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst index df136c8..a1c8c37 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 e6f76bc..0baa293 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); + + 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 + 1; + } while (end > vma->vm_end); + + mmap_write_unlock(kvm->mm); + 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_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 +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; @@ -524,7 +580,7 @@ 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 +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) - 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; }
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 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. Disable page-migration in H_SVM_INIT_START handling. Signed-off-by: Ram Pai <linuxram@us.ibm.com> --- Documentation/powerpc/ultravisor.rst | 1 + arch/powerpc/kvm/book3s_hv_uvmem.c | 98 +++++++++++++++++++++++++++--------- 2 files changed, 76 insertions(+), 23 deletions(-)