[RFC PATCH 16/28] arm64: RME: Allow populating initial contents

Steven Price
2023-01-27T11:34:12Z

The VMM needs to populate the realm with some data before starting (e.g.
a kernel and initrd). This is measured by the RMM and used as part of
the attestation later on.

Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/kvm/rme.c | 366 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 366 insertions(+)

diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index 16e0bfea98b1..3405b43e1421 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -4,6 +4,7 @@
*/

#include <linux/kvm_host.h>
+#include <linux/hugetlb.h>

#include <asm/kvm_emulate.h>
#include <asm/kvm_mmu.h>
@@ -426,6 +427,359 @@ void kvm_realm_unmap_range(struct kvm *kvm, unsigned long ipa, u64 size)
}
}

+static int realm_create_protected_data_page(struct realm *realm,
+ unsigned long ipa,
+ struct page *dst_page,
+ struct page *tmp_page)
+{
+ phys_addr_t dst_phys, tmp_phys;
+ int ret;
+
+ copy_page(page_address(tmp_page), page_address(dst_page));
+
+ dst_phys = page_to_phys(dst_page);
+ tmp_phys = page_to_phys(tmp_page);
+
+ if (rmi_granule_delegate(dst_phys))
+ return -ENXIO;
+
+ ret = rmi_data_create(dst_phys, virt_to_phys(realm->rd), ipa, tmp_phys,
+ RMI_MEASURE_CONTENT);
+
+ if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) {
+ /* Create missing RTTs and retry */
+ int level = RMI_RETURN_INDEX(ret);
+
+ ret = realm_create_rtt_levels(realm, ipa, level,
+ RME_RTT_MAX_LEVEL, NULL);
+ if (ret)
+ goto err;
+
+ ret = rmi_data_create(dst_phys, virt_to_phys(realm->rd), ipa,
+ tmp_phys, RMI_MEASURE_CONTENT);
+ }
+
+ if (ret)
+ goto err;
+
+ return 0;
+
+err:
+ if (WARN_ON(rmi_granule_undelegate(dst_phys))) {
+ /* Page can't be returned to NS world so is lost */
+ get_page(dst_page);
+ }
+ return -ENXIO;
+}
+
+static int fold_rtt(phys_addr_t rd, unsigned long addr, int level,
+ struct realm *realm)
+{
+ struct rtt_entry rtt;
+ phys_addr_t rtt_addr;
+
+ if (rmi_rtt_read_entry(rd, addr, level, &rtt))
+ return -ENXIO;
+
+ if (rtt.state != RMI_TABLE)
+ return -EINVAL;
+
+ rtt_addr = rmi_rtt_get_phys(&rtt);
+ if (rmi_rtt_fold(rtt_addr, rd, addr, level + 1))
+ return -ENXIO;
+
+ free_delegated_page(realm, rtt_addr);
+
+ return 0;
+}
+
+int realm_map_protected(struct realm *realm,
+ unsigned long hva,
+ unsigned long base_ipa,
+ struct page *dst_page,
+ unsigned long map_size,
+ struct kvm_mmu_memory_cache *memcache)
+{
+ phys_addr_t dst_phys = page_to_phys(dst_page);
+ phys_addr_t rd = virt_to_phys(realm->rd);
+ unsigned long phys = dst_phys;
+ unsigned long ipa = base_ipa;
+ unsigned long size;
+ int map_level;
+ int ret = 0;
+
+ if (WARN_ON(!IS_ALIGNED(ipa, map_size)))
+ return -EINVAL;
+
+ switch (map_size) {
+ case PAGE_SIZE:
+ map_level = 3;
+ break;
+ case RME_L2_BLOCK_SIZE:
+ map_level = 2;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (map_level < RME_RTT_MAX_LEVEL) {
+ /*
+ * A temporary RTT is needed during the map, precreate it,
+ * however if there is an error (e.g. missing parent tables)
+ * this will be handled below.
+ */
+ realm_create_rtt_levels(realm, ipa, map_level,
+ RME_RTT_MAX_LEVEL, memcache);
+ }
+
+ for (size = 0; size < map_size; size += PAGE_SIZE) {
+ if (rmi_granule_delegate(phys)) {
+ struct rtt_entry rtt;
+
+ /*
+ * It's possible we raced with another VCPU on the same
+ * fault. If the entry exists and matches then exit
+ * early and assume the other VCPU will handle the
+ * mapping.
+ */
+ if (rmi_rtt_read_entry(rd, ipa, RME_RTT_MAX_LEVEL, &rtt))
+ goto err;
+
+ // FIXME: For a block mapping this could race at level
+ // 2 or 3...
+ if (WARN_ON((rtt.walk_level != RME_RTT_MAX_LEVEL ||
+ rtt.state != RMI_ASSIGNED ||
+ rtt.desc != phys))) {
+ goto err;
+ }
+
+ return 0;
+ }
+
+ ret = rmi_data_create_unknown(phys, rd, ipa);
+
+ if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) {
+ /* Create missing RTTs and retry */
+ int level = RMI_RETURN_INDEX(ret);
+
+ ret = realm_create_rtt_levels(realm, ipa, level,
+ RME_RTT_MAX_LEVEL,
+ memcache);
+ WARN_ON(ret);
+ if (ret)
+ goto err_undelegate;
+
+ ret = rmi_data_create_unknown(phys, rd, ipa);
+ }
+ WARN_ON(ret);
+
+ if (ret)
+ goto err_undelegate;
+
+ phys += PAGE_SIZE;
+ ipa += PAGE_SIZE;
+ }
+
+ if (map_size == RME_L2_BLOCK_SIZE)
+ ret = fold_rtt(rd, base_ipa, map_level, realm);
+ if (WARN_ON(ret))
+ goto err;
+
+ return 0;
+
+err_undelegate:
+ if (WARN_ON(rmi_granule_undelegate(phys))) {
+ /* Page can't be returned to NS world so is lost */
+ get_page(phys_to_page(phys));
+ }
+err:
+ while (size > 0) {
+ phys -= PAGE_SIZE;
+ size -= PAGE_SIZE;
+ ipa -= PAGE_SIZE;
+
+ rmi_data_destroy(rd, ipa);
+
+ if (WARN_ON(rmi_granule_undelegate(phys))) {
+ /* Page can't be returned to NS world so is lost */
+ get_page(phys_to_page(phys));
+ }
+ }
+ return -ENXIO;
+}
+
+static int populate_par_region(struct kvm *kvm,
+ phys_addr_t ipa_base,
+ phys_addr_t ipa_end)
+{
+ struct realm *realm = &kvm->arch.realm;
+ struct kvm_memory_slot *memslot;
+ gfn_t base_gfn, end_gfn;
+ int idx;
+ phys_addr_t ipa;
+ int ret = 0;
+ struct page *tmp_page;
+ phys_addr_t rd = virt_to_phys(realm->rd);
+
+ base_gfn = gpa_to_gfn(ipa_base);
+ end_gfn = gpa_to_gfn(ipa_end);
+
+ idx = srcu_read_lock(&kvm->srcu);
+ memslot = gfn_to_memslot(kvm, base_gfn);
+ if (!memslot) {
+ ret = -EFAULT;
+ goto out;
+ }
+
+ /* We require the region to be contained within a single memslot */
+ if (memslot->base_gfn + memslot->npages < end_gfn) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ tmp_page = alloc_page(GFP_KERNEL);
+ if (!tmp_page) {
+ ret = -ENOMEM;
+ goto out;
+ }
+
+ mmap_read_lock(current->mm);
+
+ ipa = ipa_base;
+
+ while (ipa < ipa_end) {
+ struct vm_area_struct *vma;
+ unsigned long map_size;
+ unsigned int vma_shift;
+ unsigned long offset;
+ unsigned long hva;
+ struct page *page;
+ kvm_pfn_t pfn;
+ int level;
+
+ hva = gfn_to_hva_memslot(memslot, gpa_to_gfn(ipa));
+ vma = vma_lookup(current->mm, hva);
+ if (!vma) {
+ ret = -EFAULT;
+ break;
+ }
+
+ if (is_vm_hugetlb_page(vma))
+ vma_shift = huge_page_shift(hstate_vma(vma));
+ else
+ vma_shift = PAGE_SHIFT;
+
+ map_size = 1 << vma_shift;
+
+ /*
+ * FIXME: This causes over mapping, but there's no good
+ * solution here with the ABI as it stands
+ */
+ ipa = ALIGN_DOWN(ipa, map_size);
+
+ switch (map_size) {
+ case RME_L2_BLOCK_SIZE:
+ level = 2;
+ break;
+ case PAGE_SIZE:
+ level = 3;
+ break;
+ default:
+ WARN_ONCE(1, "Unsupport vma_shift %d", vma_shift);
+ ret = -EFAULT;
+ break;
+ }
+
+ pfn = gfn_to_pfn_memslot(memslot, gpa_to_gfn(ipa));
+
+ if (is_error_pfn(pfn)) {
+ ret = -EFAULT;
+ break;
+ }
+
+ ret = rmi_rtt_init_ripas(rd, ipa, level);
+ if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) {
+ ret = realm_create_rtt_levels(realm, ipa,
+ RMI_RETURN_INDEX(ret),
+ level, NULL);
+ if (ret)
+ break;
+ ret = rmi_rtt_init_ripas(rd, ipa, level);
+ if (ret) {
+ ret = -ENXIO;
+ break;
+ }
+ }
+
+ if (level < RME_RTT_MAX_LEVEL) {
+ /*
+ * A temporary RTT is needed during the map, precreate
+ * it, however if there is an error (e.g. missing
+ * parent tables) this will be handled in the
+ * realm_create_protected_data_page() call.
+ */
+ realm_create_rtt_levels(realm, ipa, level,
+ RME_RTT_MAX_LEVEL, NULL);
+ }
+
+ page = pfn_to_page(pfn);
+
+ for (offset = 0; offset < map_size && !ret;
+ offset += PAGE_SIZE, page++) {
+ phys_addr_t page_ipa = ipa + offset;
+
+ ret = realm_create_protected_data_page(realm, page_ipa,
+ page, tmp_page);
+ }
+ if (ret)
+ goto err_release_pfn;
+
+ if (level == 2) {
+ ret = fold_rtt(rd, ipa, level, realm);
+ if (ret)
+ goto err_release_pfn;
+ }
+
+ ipa += map_size;
+ kvm_set_pfn_accessed(pfn);
+ kvm_set_pfn_dirty(pfn);
+ kvm_release_pfn_dirty(pfn);
+err_release_pfn:
+ if (ret) {
+ kvm_release_pfn_clean(pfn);
+ break;
+ }
+ }
+
+ mmap_read_unlock(current->mm);
+ __free_page(tmp_page);
+
+out:
+ srcu_read_unlock(&kvm->srcu, idx);
+ return ret;
+}
+
+static int kvm_populate_realm(struct kvm *kvm,
+ struct kvm_cap_arm_rme_populate_realm_args *args)
+{
+ phys_addr_t ipa_base, ipa_end;
+
+ if (kvm_realm_state(kvm) != REALM_STATE_NEW)
+ return -EBUSY;
+
+ if (!IS_ALIGNED(args->populate_ipa_base, PAGE_SIZE) ||
+ !IS_ALIGNED(args->populate_ipa_size, PAGE_SIZE))
+ return -EINVAL;
+
+ ipa_base = args->populate_ipa_base;
+ ipa_end = ipa_base + args->populate_ipa_size;
+
+ if (ipa_end < ipa_base)
+ return -EINVAL;
+
+ return populate_par_region(kvm, ipa_base, ipa_end);
+}
+
static int set_ipa_state(struct kvm_vcpu *vcpu,
unsigned long ipa,
unsigned long end,
@@ -748,6 +1102,18 @@ int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
r = kvm_init_ipa_range_realm(kvm, &args);
break;
}
+ case KVM_CAP_ARM_RME_POPULATE_REALM: {
+ struct kvm_cap_arm_rme_populate_realm_args args;
+ void __user *argp = u64_to_user_ptr(cap->args[1]);
+
+ if (copy_from_user(&args, argp, sizeof(args))) {
+ r = -EFAULT;
+ break;
+ }
+
+ r = kvm_populate_realm(kvm, &args);
+ break;
+ }
default:
r = -EINVAL;
break;
--
2.34.1