[RFC PATCH 16/28] arm64: RME: Allow populating initial contents
Zhi Wang
zhi.wang.linux at gmail.com
Mon Mar 6 09:34:39 PST 2023
On Fri, 27 Jan 2023 11:29:20 +0000
Steven Price <steven.price at arm.com> wrote:
> 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 at 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;
> +}
> +
There seems no caller to the function above. Better move it to the related
patch.
> +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() has already called kvm_set_pfn_{accessed, dirty}().
> + 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;
> +
Check kvm_is_realm(kvm) here or in the kvm_realm_enable_cap().
> + if (kvm_realm_state(kvm) != REALM_STATE_NEW)
> + return -EBUSY;
Maybe -EINVAL? The realm hasn't been created (RMI_REALM_CREATE is not called
yet). The userspace shouldn't reach this path.
> +
> + 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;
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