--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Secure pages management: Migration of pages between normal and secure
+ * memory of KVM guests.
+ *
+ * Copyright 2018 Bharata B Rao, IBM Corp. <bharata@linux.ibm.com>
+ */
+
+/*
+ * A pseries guest can be run as secure guest on Ultravisor-enabled
+ * POWER platforms. On such platforms, this driver will be used to manage
+ * the movement of guest pages between the normal memory managed by
+ * hypervisor (HV) and secure memory managed by Ultravisor (UV).
+ *
+ * The page-in or page-out requests from UV will come to HV as hcalls and
+ * HV will call back into UV via ultracalls to satisfy these page requests.
+ *
+ * Private ZONE_DEVICE memory equal to the amount of secure memory
+ * available in the platform for running secure guests is hotplugged.
+ * Whenever a page belonging to the guest becomes secure, a page from this
+ * private device memory is used to represent and track that secure page
+ * on the HV side.
+ */
+
+/*
+ * Notes on locking
+ *
+ * kvm->arch.uvmem_lock is a per-guest lock that prevents concurrent
+ * page-in and page-out requests for the same GPA. Concurrent accesses
+ * can either come via UV (guest vCPUs requesting for same page)
+ * or when HV and guest simultaneously access the same page.
+ * This mutex serializes the migration of page from HV(normal) to
+ * UV(secure) and vice versa. So the serialization points are around
+ * migrate_vma routines and page-in/out routines.
+ *
+ * Per-guest mutex comes with a cost though. Mainly it serializes the
+ * fault path as page-out can occur when HV faults on accessing secure
+ * guest pages. Currently UV issues page-in requests for all the guest
+ * PFNs one at a time during early boot (UV_ESM uvcall), so this is
+ * not a cause for concern. Also currently the number of page-outs caused
+ * by HV touching secure pages is very very low. If an when UV supports
+ * overcommitting, then we might see concurrent guest driven page-outs.
+ *
+ * Locking order
+ *
+ * 1. kvm->srcu - Protects KVM memslots
+ * 2. kvm->mm->mmap_sem - find_vma, migrate_vma_pages and helpers, ksm_madvise
+ * 3. kvm->arch.uvmem_lock - protects read/writes to uvmem slots thus acting
+ * as sync-points for page-in/out
+ */
+
+/*
+ * Notes on page size
+ *
+ * Currently UV uses 2MB mappings internally, but will issue H_SVM_PAGE_IN
+ * and H_SVM_PAGE_OUT hcalls in PAGE_SIZE(64K) granularity. HV tracks
+ * secure GPAs at 64K page size and maintains one device PFN for each
+ * 64K secure GPA. UV_PAGE_IN and UV_PAGE_OUT calls by HV are also issued
+ * for 64K page at a time.
+ *
+ * HV faulting on secure pages: When HV touches any secure page, it
+ * faults and issues a UV_PAGE_OUT request with 64K page size. Currently
+ * UV splits and remaps the 2MB page if necessary and copies out the
+ * required 64K page contents.
+ *
+ * In summary, the current secure pages handling code in HV assumes
+ * 64K page size and in fact fails any page-in/page-out requests of
+ * non-64K size upfront. If and when UV starts supporting multiple
+ * page-sizes, we need to break this assumption.
+ */
+
+#include <linux/pagemap.h>
+#include <linux/migrate.h>
+#include <linux/kvm_host.h>
+#include <linux/ksm.h>
+#include <asm/ultravisor.h>
+#include <asm/mman.h>
+#include <asm/kvm_ppc.h>
+
+static struct dev_pagemap kvmppc_uvmem_pgmap;
+static unsigned long *kvmppc_uvmem_bitmap;
+static DEFINE_SPINLOCK(kvmppc_uvmem_bitmap_lock);
+
+#define KVMPPC_UVMEM_PFN (1UL << 63)
+
+struct kvmppc_uvmem_slot {
+ struct list_head list;
+ unsigned long nr_pfns;
+ unsigned long base_pfn;
+ unsigned long *pfns;
+};
+
+struct kvmppc_uvmem_page_pvt {
+ struct kvm *kvm;
+ unsigned long gpa;
+};
+
+int kvmppc_uvmem_slot_init(struct kvm *kvm, const struct kvm_memory_slot *slot)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ p = kzalloc(sizeof(*p), GFP_KERNEL);
+ if (!p)
+ return -ENOMEM;
+ p->pfns = vzalloc(array_size(slot->npages, sizeof(*p->pfns)));
+ if (!p->pfns) {
+ kfree(p);
+ return -ENOMEM;
+ }
+ p->nr_pfns = slot->npages;
+ p->base_pfn = slot->base_gfn;
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ list_add(&p->list, &kvm->arch.uvmem_pfns);
+ mutex_unlock(&kvm->arch.uvmem_lock);
+
+ return 0;
+}
+
+/*
+ * All device PFNs are already released by the time we come here.
+ */
+void kvmppc_uvmem_slot_free(struct kvm *kvm, const struct kvm_memory_slot *slot)
+{
+ struct kvmppc_uvmem_slot *p, *next;
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ list_for_each_entry_safe(p, next, &kvm->arch.uvmem_pfns, list) {
+ if (p->base_pfn == slot->base_gfn) {
+ vfree(p->pfns);
+ list_del(&p->list);
+ kfree(p);
+ break;
+ }
+ }
+ mutex_unlock(&kvm->arch.uvmem_lock);
+}
+
+static void kvmppc_uvmem_pfn_insert(unsigned long gfn, unsigned long uvmem_pfn,
+ struct kvm *kvm)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
+ if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
+ unsigned long index = gfn - p->base_pfn;
+
+ p->pfns[index] = uvmem_pfn | KVMPPC_UVMEM_PFN;
+ return;
+ }
+ }
+}
+
+static void kvmppc_uvmem_pfn_remove(unsigned long gfn, struct kvm *kvm)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
+ if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
+ p->pfns[gfn - p->base_pfn] = 0;
+ return;
+ }
+ }
+}
+
+static bool kvmppc_gfn_is_uvmem_pfn(unsigned long gfn, struct kvm *kvm,
+ unsigned long *uvmem_pfn)
+{
+ struct kvmppc_uvmem_slot *p;
+
+ list_for_each_entry(p, &kvm->arch.uvmem_pfns, list) {
+ if (gfn >= p->base_pfn && gfn < p->base_pfn + p->nr_pfns) {
+ unsigned long index = gfn - p->base_pfn;
+
+ if (p->pfns[index] & KVMPPC_UVMEM_PFN) {
+ if (uvmem_pfn)
+ *uvmem_pfn = p->pfns[index] &
+ ~KVMPPC_UVMEM_PFN;
+ return true;
+ } else
+ return false;
+ }
+ }
+ return false;
+}
+
+unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
+{
+ struct kvm_memslots *slots;
+ struct kvm_memory_slot *memslot;
+ int ret = H_SUCCESS;
+ int srcu_idx;
+
+ if (!kvmppc_uvmem_bitmap)
+ return H_UNSUPPORTED;
+
+ /* Only radix guests can be secure guests */
+ if (!kvm_is_radix(kvm))
+ return H_UNSUPPORTED;
+
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ 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;
+ }
+ }
+ kvm->arch.secure_guest |= KVMPPC_SECURE_INIT_START;
+out:
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+ 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;
+}
+
+/*
+ * Get a free device PFN from the pool
+ *
+ * Called when a normal page is moved to secure memory (UV_PAGE_IN). Device
+ * PFN will be used to keep track of the secure page on HV side.
+ *
+ * Called with kvm->arch.uvmem_lock held
+ */
+static struct page *kvmppc_uvmem_get_page(unsigned long gpa, struct kvm *kvm)
+{
+ struct page *dpage = NULL;
+ unsigned long bit, uvmem_pfn;
+ struct kvmppc_uvmem_page_pvt *pvt;
+ unsigned long pfn_last, pfn_first;
+
+ pfn_first = kvmppc_uvmem_pgmap.res.start >> PAGE_SHIFT;
+ pfn_last = pfn_first +
+ (resource_size(&kvmppc_uvmem_pgmap.res) >> PAGE_SHIFT);
+
+ spin_lock(&kvmppc_uvmem_bitmap_lock);
+ bit = find_first_zero_bit(kvmppc_uvmem_bitmap,
+ pfn_last - pfn_first);
+ if (bit >= (pfn_last - pfn_first))
+ goto out;
+ bitmap_set(kvmppc_uvmem_bitmap, bit, 1);
+ spin_unlock(&kvmppc_uvmem_bitmap_lock);
+
+ pvt = kzalloc(sizeof(*pvt), GFP_KERNEL);
+ if (!pvt)
+ goto out_clear;
+
+ uvmem_pfn = bit + pfn_first;
+ kvmppc_uvmem_pfn_insert(gpa >> PAGE_SHIFT, uvmem_pfn, kvm);
+
+ pvt->gpa = gpa;
+ pvt->kvm = kvm;
+
+ dpage = pfn_to_page(uvmem_pfn);
+ dpage->zone_device_data = pvt;
+ get_page(dpage);
+ lock_page(dpage);
+ return dpage;
+out_clear:
+ spin_lock(&kvmppc_uvmem_bitmap_lock);
+ bitmap_clear(kvmppc_uvmem_bitmap, bit, 1);
+out:
+ spin_unlock(&kvmppc_uvmem_bitmap_lock);
+ return NULL;
+}
+
+/*
+ * Alloc a PFN from private device memory pool and 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, bool *downgrade)
+{
+ unsigned long src_pfn, dst_pfn = 0;
+ struct migrate_vma mig;
+ struct page *spage;
+ unsigned long pfn;
+ struct page *dpage;
+ int ret = 0;
+
+ memset(&mig, 0, sizeof(mig));
+ mig.vma = vma;
+ mig.start = start;
+ mig.end = end;
+ 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;
+
+ if (!(*mig.src & MIGRATE_PFN_MIGRATE)) {
+ ret = -1;
+ goto out_finalize;
+ }
+
+ dpage = kvmppc_uvmem_get_page(gpa, kvm);
+ if (!dpage) {
+ ret = -1;
+ 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);
+
+ *mig.dst = migrate_pfn(page_to_pfn(dpage)) | MIGRATE_PFN_LOCKED;
+ migrate_vma_pages(&mig);
+out_finalize:
+ migrate_vma_finalize(&mig);
+ return ret;
+}
+
+/*
+ * H_SVM_PAGE_IN: Move page from normal memory to secure memory.
+ */
+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;
+ unsigned long gfn = gpa >> page_shift;
+ int ret;
+
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+ return H_UNSUPPORTED;
+
+ if (page_shift != PAGE_SHIFT)
+ return H_P3;
+
+ if (flags)
+ return H_P2;
+
+ ret = H_PARAMETER;
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ down_write(&kvm->mm->mmap_sem);
+
+ start = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(start))
+ goto out;
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ /* Fail the page-in request of an already paged-in page */
+ if (kvmppc_gfn_is_uvmem_pfn(gfn, kvm, NULL))
+ goto out_unlock;
+
+ end = start + (1UL << page_shift);
+ vma = find_vma_intersection(kvm->mm, start, end);
+ 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))
+ 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);
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+ return ret;
+}
+
+/*
+ * Provision a new page on HV side and copy over the contents
+ * from secure memory using UV_PAGE_OUT uvcall.
+ */
+static int
+kvmppc_svm_page_out(struct vm_area_struct *vma, unsigned long start,
+ unsigned long end, unsigned long page_shift,
+ struct kvm *kvm, unsigned long gpa)
+{
+ unsigned long src_pfn, dst_pfn = 0;
+ struct migrate_vma mig;
+ struct page *dpage, *spage;
+ unsigned long pfn;
+ int ret = U_SUCCESS;
+
+ memset(&mig, 0, sizeof(mig));
+ mig.vma = vma;
+ mig.start = start;
+ mig.end = end;
+ mig.src = &src_pfn;
+ mig.dst = &dst_pfn;
+
+ mutex_lock(&kvm->arch.uvmem_lock);
+ /* The requested page is already paged-out, nothing to do */
+ if (!kvmppc_gfn_is_uvmem_pfn(gpa >> page_shift, kvm, NULL))
+ goto out;
+
+ ret = migrate_vma_setup(&mig);
+ if (ret)
+ return ret;
+
+ spage = migrate_pfn_to_page(*mig.src);
+ if (!spage || !(*mig.src & MIGRATE_PFN_MIGRATE))
+ goto out_finalize;
+
+ if (!is_zone_device_page(spage))
+ goto out_finalize;
+
+ dpage = alloc_page_vma(GFP_HIGHUSER, vma, start);
+ if (!dpage) {
+ ret = -1;
+ goto out_finalize;
+ }
+
+ lock_page(dpage);
+ pfn = page_to_pfn(dpage);
+
+ ret = uv_page_out(kvm->arch.lpid, pfn << page_shift,
+ gpa, 0, page_shift);
+ if (ret == U_SUCCESS)
+ *mig.dst = migrate_pfn(pfn) | MIGRATE_PFN_LOCKED;
+ else {
+ unlock_page(dpage);
+ __free_page(dpage);
+ goto out_finalize;
+ }
+
+ migrate_vma_pages(&mig);
+out_finalize:
+ migrate_vma_finalize(&mig);
+out:
+ mutex_unlock(&kvm->arch.uvmem_lock);
+ return ret;
+}
+
+/*
+ * Fault handler callback that gets called when HV touches any page that
+ * has been moved to secure memory, we ask UV to give back the page by
+ * issuing UV_PAGE_OUT uvcall.
+ *
+ * This eventually results in dropping of device PFN and the newly
+ * provisioned page/PFN gets populated in QEMU page tables.
+ */
+static vm_fault_t kvmppc_uvmem_migrate_to_ram(struct vm_fault *vmf)
+{
+ struct kvmppc_uvmem_page_pvt *pvt = vmf->page->zone_device_data;
+
+ if (kvmppc_svm_page_out(vmf->vma, vmf->address,
+ vmf->address + PAGE_SIZE, PAGE_SHIFT,
+ pvt->kvm, pvt->gpa))
+ return VM_FAULT_SIGBUS;
+ else
+ return 0;
+}
+
+/*
+ * Release the device PFN back to the pool
+ *
+ * Gets called when secure page becomes a normal page during H_SVM_PAGE_OUT.
+ * Gets called with kvm->arch.uvmem_lock held.
+ */
+static void kvmppc_uvmem_page_free(struct page *page)
+{
+ unsigned long pfn = page_to_pfn(page) -
+ (kvmppc_uvmem_pgmap.res.start >> PAGE_SHIFT);
+ struct kvmppc_uvmem_page_pvt *pvt;
+
+ spin_lock(&kvmppc_uvmem_bitmap_lock);
+ bitmap_clear(kvmppc_uvmem_bitmap, pfn, 1);
+ spin_unlock(&kvmppc_uvmem_bitmap_lock);
+
+ pvt = page->zone_device_data;
+ page->zone_device_data = NULL;
+ kvmppc_uvmem_pfn_remove(pvt->gpa >> PAGE_SHIFT, pvt->kvm);
+ kfree(pvt);
+}
+
+static const struct dev_pagemap_ops kvmppc_uvmem_ops = {
+ .page_free = kvmppc_uvmem_page_free,
+ .migrate_to_ram = kvmppc_uvmem_migrate_to_ram,
+};
+
+/*
+ * H_SVM_PAGE_OUT: Move page from secure memory to normal memory.
+ */
+unsigned long
+kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gpa,
+ unsigned long flags, unsigned long page_shift)
+{
+ unsigned long gfn = gpa >> page_shift;
+ unsigned long start, end;
+ struct vm_area_struct *vma;
+ int srcu_idx;
+ int ret;
+
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+ return H_UNSUPPORTED;
+
+ if (page_shift != PAGE_SHIFT)
+ return H_P3;
+
+ if (flags)
+ return H_P2;
+
+ ret = H_PARAMETER;
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ down_read(&kvm->mm->mmap_sem);
+ start = gfn_to_hva(kvm, gfn);
+ if (kvm_is_error_hva(start))
+ goto out;
+
+ end = start + (1UL << page_shift);
+ vma = find_vma_intersection(kvm->mm, start, end);
+ if (!vma || vma->vm_start > start || vma->vm_end < end)
+ goto out;
+
+ if (!kvmppc_svm_page_out(vma, start, end, page_shift, kvm, gpa))
+ ret = H_SUCCESS;
+out:
+ up_read(&kvm->mm->mmap_sem);
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+ return ret;
+}
+
+static u64 kvmppc_get_secmem_size(void)
+{
+ struct device_node *np;
+ int i, len;
+ const __be32 *prop;
+ u64 size = 0;
+
+ np = of_find_compatible_node(NULL, NULL, "ibm,uv-firmware");
+ if (!np)
+ goto out;
+
+ prop = of_get_property(np, "secure-memory-ranges", &len);
+ if (!prop)
+ goto out_put;
+
+ for (i = 0; i < len / (sizeof(*prop) * 4); i++)
+ size += of_read_number(prop + (i * 4) + 2, 2);
+
+out_put:
+ of_node_put(np);
+out:
+ return size;
+}
+
+int kvmppc_uvmem_init(void)
+{
+ int ret = 0;
+ unsigned long size;
+ struct resource *res;
+ void *addr;
+ unsigned long pfn_last, pfn_first;
+
+ size = kvmppc_get_secmem_size();
+ if (!size) {
+ /*
+ * Don't fail the initialization of kvm-hv module if
+ * the platform doesn't export ibm,uv-firmware node.
+ * Let normal guests run on such PEF-disabled platform.
+ */
+ pr_info("KVMPPC-UVMEM: No support for secure guests\n");
+ goto out;
+ }
+
+ res = request_free_mem_region(&iomem_resource, size, "kvmppc_uvmem");
+ if (IS_ERR(res)) {
+ ret = PTR_ERR(res);
+ goto out;
+ }
+
+ kvmppc_uvmem_pgmap.type = MEMORY_DEVICE_PRIVATE;
+ kvmppc_uvmem_pgmap.res = *res;
+ kvmppc_uvmem_pgmap.ops = &kvmppc_uvmem_ops;
+ addr = memremap_pages(&kvmppc_uvmem_pgmap, NUMA_NO_NODE);
+ if (IS_ERR(addr)) {
+ ret = PTR_ERR(addr);
+ goto out_free_region;
+ }
+
+ pfn_first = res->start >> PAGE_SHIFT;
+ pfn_last = pfn_first + (resource_size(res) >> PAGE_SHIFT);
+ kvmppc_uvmem_bitmap = kcalloc(BITS_TO_LONGS(pfn_last - pfn_first),
+ sizeof(unsigned long), GFP_KERNEL);
+ if (!kvmppc_uvmem_bitmap) {
+ ret = -ENOMEM;
+ goto out_unmap;
+ }
+
+ pr_info("KVMPPC-UVMEM: Secure Memory size 0x%lx\n", size);
+ return ret;
+out_unmap:
+ memunmap_pages(&kvmppc_uvmem_pgmap);
+out_free_region:
+ release_mem_region(res->start, size);
+out:
+ return ret;
+}
+
+void kvmppc_uvmem_free(void)
+{
+ memunmap_pages(&kvmppc_uvmem_pgmap);
+ release_mem_region(kvmppc_uvmem_pgmap.res.start,
+ resource_size(&kvmppc_uvmem_pgmap.res));
+ kfree(kvmppc_uvmem_bitmap);
+}
projects / openwrt / staging / blogic.git / commitdiff