At runtime if the realm guest accesses memory which hasn't yet been
mapped then KVM needs to either populate the region or fault the guest.
For memory in the lower (protected) region of IPA a fresh page is
provided to the RMM which will zero the contents. For memory in the
upper (shared) region of IPA, the memory from the memslot is mapped
into the realm VM non secure.
Signed-off-by: Steven Price <steven.price@xxxxxxx>
---
Changes since v5:
* Reduce use of struct page in preparation for supporting the RMM
having a different page size to the host.
* Handle a race when delegating a page where another CPU has faulted on
a the same page (and already delegated the physical page) but not yet
mapped it. In this case simply return to the guest to either use the
mapping from the other CPU (or refault if the race is lost).
* The changes to populate_par_region() are moved into the previous
patch where they belong.
Changes since v4:
* Code cleanup following review feedback.
* Drop the PTE_SHARED bit when creating unprotected page table entries.
This is now set by the RMM and the host has no control of it and the
spec requires the bit to be set to zero.
Changes since v2:
* Avoid leaking memory if failing to map it in the realm.
* Correctly mask RTT based on LPA2 flag (see rtt_get_phys()).
* Adapt to changes in previous patches.
---
arch/arm64/include/asm/kvm_emulate.h | 10 ++
arch/arm64/include/asm/kvm_rme.h | 10 ++
arch/arm64/kvm/mmu.c | 124 +++++++++++++++++++--
arch/arm64/kvm/rme.c | 156 +++++++++++++++++++++++++++
4 files changed, 293 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index ec2b6d9c9c07..b13e367b6972 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -720,6 +720,16 @@ static inline bool kvm_realm_is_created(struct kvm *kvm)
return kvm_is_realm(kvm) && kvm_realm_state(kvm) != REALM_STATE_NONE;
}
+static inline gpa_t kvm_gpa_from_fault(struct kvm *kvm, phys_addr_t fault_ipa)
+{
+ if (kvm_is_realm(kvm)) {
+ struct realm *realm = &kvm->arch.realm;
+
+ return fault_ipa & ~BIT(realm->ia_bits - 1);
+ }
+ return fault_ipa;
+}
+
static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu)
{
if (static_branch_unlikely(&kvm_rme_is_available))
diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index 0410650cd545..158f77e24a26 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -99,6 +99,16 @@ void kvm_realm_unmap_range(struct kvm *kvm,
unsigned long ipa,
u64 size,
bool unmap_private);
+int realm_map_protected(struct realm *realm,
+ unsigned long base_ipa,
+ kvm_pfn_t pfn,
+ unsigned long size,
+ struct kvm_mmu_memory_cache *memcache);
+int realm_map_non_secure(struct realm *realm,
+ unsigned long ipa,
+ kvm_pfn_t pfn,
+ unsigned long size,
+ struct kvm_mmu_memory_cache *memcache);
int realm_set_ipa_state(struct kvm_vcpu *vcpu,
unsigned long addr, unsigned long end,
unsigned long ripas,
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index b100d4b3aa29..e88714903ce5 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -325,8 +325,13 @@ static void __unmap_stage2_range(struct kvm_s2_mmu *mmu, phys_addr_t start, u64
lockdep_assert_held_write(&kvm->mmu_lock);
WARN_ON(size & ~PAGE_MASK);
- WARN_ON(stage2_apply_range(mmu, start, end, kvm_pgtable_stage2_unmap,
- may_block));
+
+ if (kvm_is_realm(kvm))
+ kvm_realm_unmap_range(kvm, start, size, !only_shared);
+ else
+ WARN_ON(stage2_apply_range(mmu, start, end,
+ kvm_pgtable_stage2_unmap,
+ may_block));
}
void kvm_stage2_unmap_range(struct kvm_s2_mmu *mmu, phys_addr_t start,
@@ -346,7 +351,10 @@ static void stage2_flush_memslot(struct kvm *kvm,
phys_addr_t addr = memslot->base_gfn << PAGE_SHIFT;
phys_addr_t end = addr + PAGE_SIZE * memslot->npages;
- kvm_stage2_flush_range(&kvm->arch.mmu, addr, end);
+ if (kvm_is_realm(kvm))
+ kvm_realm_unmap_range(kvm, addr, end - addr, false);
+ else
+ kvm_stage2_flush_range(&kvm->arch.mmu, addr, end);
}
/**
@@ -1037,6 +1045,10 @@ void stage2_unmap_vm(struct kvm *kvm)
struct kvm_memory_slot *memslot;
int idx, bkt;
+ /* For realms this is handled by the RMM so nothing to do here */
+ if (kvm_is_realm(kvm))
+ return;
+
idx = srcu_read_lock(&kvm->srcu);
mmap_read_lock(current->mm);
write_lock(&kvm->mmu_lock);
@@ -1062,6 +1074,7 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
if (kvm_is_realm(kvm) &&
(kvm_realm_state(kvm) != REALM_STATE_DEAD &&
kvm_realm_state(kvm) != REALM_STATE_NONE)) {
+ kvm_stage2_unmap_range(mmu, 0, (~0ULL) & PAGE_MASK, false);
write_unlock(&kvm->mmu_lock);
kvm_realm_destroy_rtts(kvm, pgt->ia_bits);
@@ -1446,6 +1459,76 @@ static bool kvm_vma_mte_allowed(struct vm_area_struct *vma)
return vma->vm_flags & VM_MTE_ALLOWED;
}
+static int realm_map_ipa(struct kvm *kvm, phys_addr_t ipa,
+ kvm_pfn_t pfn, unsigned long map_size,
+ enum kvm_pgtable_prot prot,
+ struct kvm_mmu_memory_cache *memcache)
+{
+ struct realm *realm = &kvm->arch.realm;
+
+ if (WARN_ON(!(prot & KVM_PGTABLE_PROT_W)))
+ return -EFAULT;
+
+ if (!realm_is_addr_protected(realm, ipa))
+ return realm_map_non_secure(realm, ipa, pfn, map_size,
+ memcache);
+
+ return realm_map_protected(realm, ipa, pfn, map_size, memcache);
+}
+
+static int private_memslot_fault(struct kvm_vcpu *vcpu,
+ phys_addr_t fault_ipa,
+ struct kvm_memory_slot *memslot)
+{
+ struct kvm *kvm = vcpu->kvm;
+ gpa_t gpa = kvm_gpa_from_fault(kvm, fault_ipa);
+ gfn_t gfn = gpa >> PAGE_SHIFT;
+ bool priv_exists = kvm_mem_is_private(kvm, gfn);
+ struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
+ struct page *page;
+ kvm_pfn_t pfn;
+ int ret;
+ /*
+ * For Realms, the shared address is an alias of the private GPA with
+ * the top bit set. Thus is the fault address matches the GPA then it
+ * is the private alias.
+ */
+ bool is_priv_gfn = (gpa == fault_ipa);
+
+ if (priv_exists != is_priv_gfn) {
+ kvm_prepare_memory_fault_exit(vcpu,
+ gpa,
+ PAGE_SIZE,
+ kvm_is_write_fault(vcpu),
+ false, is_priv_gfn);
+
+ return -EFAULT;
+ }
+
+ if (!is_priv_gfn) {
+ /* Not a private mapping, handling normally */
+ return -EINVAL;
+ }
+
+ ret = kvm_mmu_topup_memory_cache(memcache,
+ kvm_mmu_cache_min_pages(vcpu->arch.hw_mmu));
+ if (ret)
+ return ret;
+
+ ret = kvm_gmem_get_pfn(kvm, memslot, gfn, &pfn, &page, NULL);
+ if (ret)
+ return ret;
+
+ /* FIXME: Should be able to use bigger than PAGE_SIZE mappings */
+ ret = realm_map_ipa(kvm, fault_ipa, pfn, PAGE_SIZE, KVM_PGTABLE_PROT_W,
+ memcache);
+ if (!ret)
+ return 1; /* Handled */
+
+ put_page(page);
+ return ret;
+}
+
static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
struct kvm_s2_trans *nested,
struct kvm_memory_slot *memslot, unsigned long hva,
@@ -1472,6 +1555,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
if (fault_is_perm)
fault_granule = kvm_vcpu_trap_get_perm_fault_granule(vcpu);
write_fault = kvm_is_write_fault(vcpu);
+
+ /*
+ * Realms cannot map protected pages read-only
+ * FIXME: It should be possible to map unprotected pages read-only
+ */
+ if (vcpu_is_rec(vcpu))
+ write_fault = true;
+
exec_fault = kvm_vcpu_trap_is_exec_fault(vcpu);
VM_BUG_ON(write_fault && exec_fault);
@@ -1579,7 +1670,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
ipa &= ~(vma_pagesize - 1);
}
- gfn = ipa >> PAGE_SHIFT;
+ gfn = kvm_gpa_from_fault(kvm, ipa) >> PAGE_SHIFT;
mte_allowed = kvm_vma_mte_allowed(vma);
vfio_allow_any_uc = vma->vm_flags & VM_ALLOW_ANY_UNCACHED;
@@ -1660,7 +1751,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
* If we are not forced to use page mapping, check if we are
* backed by a THP and thus use block mapping if possible.
*/
- if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) {
+ /* FIXME: We shouldn't need to disable this for realms */
+ if (vma_pagesize == PAGE_SIZE && !(force_pte || device || kvm_is_realm(kvm))) {
if (fault_is_perm && fault_granule > PAGE_SIZE)
vma_pagesize = fault_granule;
else
@@ -1712,6 +1804,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
*/
prot &= ~KVM_NV_GUEST_MAP_SZ;
ret = kvm_pgtable_stage2_relax_perms(pgt, fault_ipa, prot);
+ } else if (kvm_is_realm(kvm)) {
+ ret = realm_map_ipa(kvm, fault_ipa, pfn, vma_pagesize,
+ prot, memcache);
} else {
ret = kvm_pgtable_stage2_map(pgt, fault_ipa, vma_pagesize,
__pfn_to_phys(pfn), prot,
@@ -1854,8 +1949,15 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
nested = &nested_trans;
}
- gfn = ipa >> PAGE_SHIFT;
+ gfn = kvm_gpa_from_fault(vcpu->kvm, ipa) >> PAGE_SHIFT;
memslot = gfn_to_memslot(vcpu->kvm, gfn);
+
+ if (kvm_slot_can_be_private(memslot)) {
+ ret = private_memslot_fault(vcpu, ipa, memslot);
+ if (ret != -EINVAL)
+ goto out;
+ }
+
hva = gfn_to_hva_memslot_prot(memslot, gfn, &writable);
write_fault = kvm_is_write_fault(vcpu);
if (kvm_is_error_hva(hva) || (write_fault && !writable)) {
@@ -1899,7 +2001,7 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu)
* of the page size.
*/
ipa |= kvm_vcpu_get_hfar(vcpu) & GENMASK(11, 0);
- ret = io_mem_abort(vcpu, ipa);
+ ret = io_mem_abort(vcpu, kvm_gpa_from_fault(vcpu->kvm, ipa));
goto out_unlock;
}
@@ -1947,6 +2049,10 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (!kvm->arch.mmu.pgt)
return false;
+ /* We don't support aging for Realms */
+ if (kvm_is_realm(kvm))
+ return true;
+
return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
range->start << PAGE_SHIFT,
size, true);
@@ -1963,6 +2069,10 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
if (!kvm->arch.mmu.pgt)
return false;
+ /* We don't support aging for Realms */
+ if (kvm_is_realm(kvm))
+ return true;
+
return kvm_pgtable_stage2_test_clear_young(kvm->arch.mmu.pgt,
range->start << PAGE_SHIFT,
size, false);
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index d4561e368cd5..146ef598a581 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -602,6 +602,162 @@ static int fold_rtt(struct realm *realm, unsigned long addr, int level)
return 0;
}
+int realm_map_protected(struct realm *realm,
+ unsigned long ipa,
+ kvm_pfn_t pfn,
+ unsigned long map_size,
+ struct kvm_mmu_memory_cache *memcache)
+{
+ phys_addr_t phys = __pfn_to_phys(pfn);
+ phys_addr_t rd = virt_to_phys(realm->rd);
+ unsigned long base_ipa = 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 RMM_L2_BLOCK_SIZE:
+ map_level = 2;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (map_level < RMM_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,
+ RMM_RTT_MAX_LEVEL, memcache);
+ }
+
+ for (size = 0; size < map_size; size += PAGE_SIZE) {
+ if (rmi_granule_delegate(phys)) {
+ /*
+ * It's likely we raced with another VCPU on the same
+ * fault. Assume the other VCPU has handled the fault
+ * and return to the guest.
+ */
+ return 0;
+ }
+
+ ret = rmi_data_create_unknown(rd, phys, 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,
+ RMM_RTT_MAX_LEVEL,
+ memcache);
+ WARN_ON(ret);
+ if (ret)
+ goto err_undelegate;
+
+ ret = rmi_data_create_unknown(rd, phys, ipa);
+ }
+ WARN_ON(ret);
+
+ if (ret)
+ goto err_undelegate;
+
+ phys += PAGE_SIZE;
+ ipa += PAGE_SIZE;
+ }
+
+ if (map_size == RMM_L2_BLOCK_SIZE)
+ ret = fold_rtt(realm, base_ipa, map_level);
+ 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) {
+ unsigned long data, top;
+
+ phys -= PAGE_SIZE;
+ size -= PAGE_SIZE;
+ ipa -= PAGE_SIZE;
+
+ WARN_ON(rmi_data_destroy(rd, ipa, &data, &top));
+
+ 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;
+}
+
+int realm_map_non_secure(struct realm *realm,
+ unsigned long ipa,
+ kvm_pfn_t pfn,
+ unsigned long map_size,
+ struct kvm_mmu_memory_cache *memcache)
+{
+ phys_addr_t rd = virt_to_phys(realm->rd);
+ int map_level;
+ int ret = 0;
+ unsigned long desc = __pfn_to_phys(pfn) |
+ PTE_S2_MEMATTR(MT_S2_FWB_NORMAL) |
+ /* FIXME: Read+Write permissions for now */
+ (3 << 6);
+
+ if (WARN_ON(!IS_ALIGNED(ipa, map_size)))
+ return -EINVAL;
+
+ switch (map_size) {
+ case PAGE_SIZE:
+ map_level = 3;
+ break;
+ case RMM_L2_BLOCK_SIZE:
+ map_level = 2;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ ret = rmi_rtt_map_unprotected(rd, ipa, map_level, desc);
+
+ 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, map_level,
+ memcache);
+ if (WARN_ON(ret))
+ return -ENXIO;
+
+ ret = rmi_rtt_map_unprotected(rd, ipa, map_level, desc);
+ }
+ /*
+ * RMI_ERROR_RTT can be reported for two reasons: either the RTT tables
+ * are not there, or there is an RTTE already present for the address.
+ * The call to realm_create_rtt_levels() above handles the first case,
+ * and in the second case this indicates that another thread has
+ * already populated the RTTE for us, so we can ignore the error and
+ * continue.
+ */
+ if (WARN_ON(ret && RMI_RETURN_STATUS(ret) != RMI_ERROR_RTT))
+ return -ENXIO;
+
+ return 0;
+}
+
static int populate_par_region(struct kvm *kvm,
phys_addr_t ipa_base,
phys_addr_t ipa_end,
--
2.43.0
