From dfaa973ae9605e1731eaef9f30c2b056346a4efc Mon Sep 17 00:00:00 2001 From: Ram Pai Date: Mon, 27 Jul 2020 11:07:17 -0700 Subject: [PATCH] KVM: PPC: Book3S HV: In H_SVM_INIT_DONE, migrate remaining normal-GFNs to secure-GFNs The Ultravisor is expected to explicitly call H_SVM_PAGE_IN for all the pages of the SVM before calling H_SVM_INIT_DONE. This causes a huge delay in tranistioning the VM to SVM. The Ultravisor is only interested in the pages that contain the kernel, initrd and other important data structures. The rest contain throw-away content. However if not all pages are requested by the Ultravisor, the Hypervisor continues to consider the GFNs corresponding to the non-requested pages as normal GFNs. This can lead to data-corruption and undefined behavior. In H_SVM_INIT_DONE handler, move all the PFNs associated with the SVM's GFNs to secure-PFNs. Skip the GFNs that are already Paged-in or Shared or Paged-in followed by a Paged-out. Reviewed-by: Bharata B Rao Signed-off-by: Ram Pai Signed-off-by: Paul Mackerras --- Documentation/powerpc/ultravisor.rst | 2 + arch/powerpc/kvm/book3s_hv_uvmem.c | 154 +++++++++++++++++++++++---- 2 files changed, 134 insertions(+), 22 deletions(-) diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst index a1c8c37159a1..ba6b1bf1cc44 100644 --- a/Documentation/powerpc/ultravisor.rst +++ b/Documentation/powerpc/ultravisor.rst @@ -934,6 +934,8 @@ Return values * H_UNSUPPORTED if called from the wrong context (e.g. from an SVM or before an H_SVM_INIT_START hypercall). + * H_STATE if the hypervisor could not successfully + transition the VM to Secure VM. Description ~~~~~~~~~~~ diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index 1b2b0293da40..a1664ae4d81f 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -93,6 +93,7 @@ #include #include #include +#include static struct dev_pagemap kvmppc_uvmem_pgmap; static unsigned long *kvmppc_uvmem_bitmap; @@ -348,6 +349,41 @@ static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm, return false; } +/* + * starting from *gfn search for the next available GFN that is not yet + * transitioned to a secure GFN. return the value of that GFN in *gfn. If a + * GFN is found, return true, else return false + * + * Must be called with kvm->arch.uvmem_lock held. + */ +static bool kvmppc_next_nontransitioned_gfn(const struct kvm_memory_slot *memslot, + struct kvm *kvm, unsigned long *gfn) +{ + struct kvmppc_uvmem_slot *p; + bool ret = false; + unsigned long i; + + list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) + if (*gfn >= p->base_pfn && *gfn < p->base_pfn + p->nr_pfns) + break; + if (!p) + return ret; + /* + * The code below assumes, one to one correspondence between + * kvmppc_uvmem_slot and memslot. + */ + for (i = *gfn; i < p->base_pfn + p->nr_pfns; i++) { + unsigned long index = i - p->base_pfn; + + if (!(p->pfns[index] & KVMPPC_GFN_FLAG_MASK)) { + *gfn = i; + ret = true; + break; + } + } + return ret; +} + static int kvmppc_memslot_page_merge(struct kvm *kvm, const struct kvm_memory_slot *memslot, bool merge) { @@ -460,16 +496,6 @@ unsigned long kvmppc_h_svm_init_start(struct kvm *kvm) return ret; } -unsigned long kvmppc_h_svm_init_done(struct kvm *kvm) -{ - if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START)) - return H_UNSUPPORTED; - - kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE; - pr_info("LPID %d went secure\n", kvm->arch.lpid); - return H_SUCCESS; -} - /* * Drop device pages that we maintain for the secure guest * @@ -588,12 +614,14 @@ out: } /* - * Alloc a PFN from private device memory pool and copy page from normal - * memory to secure memory using UV_PAGE_IN uvcall. + * Alloc a PFN from private device memory pool. If @pagein is true, + * copy page from normal memory to secure memory using UV_PAGE_IN uvcall. */ -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) +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 pagein) { unsigned long src_pfn, dst_pfn = 0; struct migrate_vma mig; @@ -624,11 +652,16 @@ static int kvmppc_svm_page_in(struct vm_area_struct *vma, unsigned long start, goto out_finalize; } - pfn = *mig.src >> MIGRATE_PFN_SHIFT; - spage = migrate_pfn_to_page(*mig.src); - if (spage) - uv_page_in(kvm->arch.lpid, pfn << page_shift, gpa, 0, - page_shift); + if (pagein) { + pfn = *mig.src >> MIGRATE_PFN_SHIFT; + spage = migrate_pfn_to_page(*mig.src); + if (spage) { + ret = uv_page_in(kvm->arch.lpid, pfn << page_shift, + gpa, 0, page_shift); + if (ret) + goto out_finalize; + } + } *mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED; migrate_vma_pages(&mig); @@ -637,6 +670,80 @@ out_finalize: return ret; } +static int kvmppc_uv_migrate_mem_slot(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + unsigned long gfn = memslot->base_gfn; + struct vm_area_struct *vma; + unsigned long start, end; + int ret = 0; + + mmap_read_lock(kvm->mm); + mutex_lock(&kvm->arch.uvmem_lock); + while (kvmppc_next_nontransitioned_gfn(memslot, kvm, &gfn)) { + ret = H_STATE; + start = gfn_to_hva(kvm, gfn); + if (kvm_is_error_hva(start)) + break; + + end = start + (1UL << PAGE_SHIFT); + vma = find_vma_intersection(kvm->mm, start, end); + if (!vma || vma->vm_start > start || vma->vm_end < end) + break; + + ret = kvmppc_svm_page_in(vma, start, end, + (gfn << PAGE_SHIFT), kvm, PAGE_SHIFT, false); + if (ret) { + ret = H_STATE; + break; + } + + /* relinquish the cpu if needed */ + cond_resched(); + } + mutex_unlock(&kvm->arch.uvmem_lock); + mmap_read_unlock(kvm->mm); + return ret; +} + +unsigned long kvmppc_h_svm_init_done(struct kvm *kvm) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *memslot; + int srcu_idx; + long ret = H_SUCCESS; + + if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START)) + return H_UNSUPPORTED; + + /* migrate any unmoved normal pfn to device pfns*/ + srcu_idx = srcu_read_lock(&kvm->srcu); + slots = kvm_memslots(kvm); + kvm_for_each_memslot(memslot, slots) { + ret = kvmppc_uv_migrate_mem_slot(kvm, memslot); + if (ret) { + /* + * The pages will remain transitioned. + * Its the callers responsibility to + * terminate the VM, which will undo + * all state of the VM. Till then + * this VM is in a erroneous state. + * Its KVMPPC_SECURE_INIT_DONE will + * remain unset. + */ + ret = H_STATE; + goto out; + } + } + + kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_DONE; + pr_info("LPID %d went secure\n", kvm->arch.lpid); + +out: + srcu_read_unlock(&kvm->srcu, srcu_idx); + return ret; +} + /* * Shares the page with HV, thus making it a normal page. * @@ -745,8 +852,11 @@ 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)) - ret = H_SUCCESS; + if (kvmppc_svm_page_in(vma, start, end, gpa, kvm, page_shift, + true)) + goto out_unlock; + + ret = H_SUCCESS; out_unlock: mutex_unlock(&kvm->arch.uvmem_lock);