[PATCH v13 26/48] arm64: RMI: Create the realm descriptor

Steven Price
2026-03-18T15:56:00Z

Creating a realm involves first creating a realm descriptor (RD). This
involves passing the configuration information to the RMM. Do this as
part of realm_ensure_created() so that the realm is created when it is
first needed.

Signed-off-by: Steven Price <steven.price@arm.com>
---
Changes since v12:
* Since RMM page size is now equal to the host's page size various
calculations are simplified.
* Switch to using range based APIs to delegate/undelegate.
* VMID handling is now handled entirely by the RMM.
---
arch/arm64/kvm/rmi.c | 94 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 92 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index 38349c7b34f4..d5fee203824b 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c
@@ -649,6 +649,83 @@ static void realm_unmap_shared_range(struct kvm *kvm,
start, end);
}

+static int realm_create_rd(struct kvm *kvm)
+{
+ struct realm *realm = &kvm->arch.realm;
+ struct realm_params *params = realm->params;
+ void *rd = NULL;
+ phys_addr_t rd_phys, params_phys;
+ size_t pgd_size = kvm_pgtable_stage2_pgd_size(kvm->arch.mmu.vtcr);
+ int i, r;
+
+ realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+
+ if (WARN_ON(realm->rd || !realm->params))
+ return -EEXIST;
+
+ rd = (void *)__get_free_page(GFP_KERNEL);
+ if (!rd)
+ return -ENOMEM;
+
+ rd_phys = virt_to_phys(rd);
+ if (delegate_page(rd_phys)) {
+ r = -ENXIO;
+ goto free_rd;
+ }
+
+ if (delegate_range(kvm->arch.mmu.pgd_phys, pgd_size)) {
+ r = -ENXIO;
+ goto out_undelegate_tables;
+ }
+
+ params->s2sz = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+ params->rtt_level_start = get_start_level(realm);
+ params->rtt_num_start = pgd_size / PAGE_SIZE;
+ params->rtt_base = kvm->arch.mmu.pgd_phys;
+
+ if (kvm->arch.arm_pmu) {
+ params->pmu_num_ctrs = kvm->arch.nr_pmu_counters;
+ params->flags |= RMI_REALM_PARAM_FLAG_PMU;
+ }
+
+ if (kvm_lpa2_is_enabled())
+ params->flags |= RMI_REALM_PARAM_FLAG_LPA2;
+
+ params_phys = virt_to_phys(params);
+
+ if (rmi_realm_create(rd_phys, params_phys)) {
+ r = -ENXIO;
+ goto out_undelegate_tables;
+ }
+
+ if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) {
+ WARN_ON(rmi_realm_destroy(rd_phys));
+ r = -ENXIO;
+ goto out_undelegate_tables;
+ }
+
+ realm->rd = rd;
+ WRITE_ONCE(realm->state, REALM_STATE_NEW);
+ /* The realm is up, free the parameters. */
+ free_page((unsigned long)realm->params);
+ realm->params = NULL;
+
+ return 0;
+
+out_undelegate_tables:
+ if (WARN_ON(undelegate_range(kvm->arch.mmu.pgd_phys, i))) {
+ /* Leak the pages if they cannot be returned */
+ kvm->arch.mmu.pgt = NULL;
+ }
+ if (WARN_ON(undelegate_page(rd_phys))) {
+ /* Leak the page if it isn't returned */
+ return r;
+ }
+free_rd:
+ free_page((unsigned long)rd);
+ return r;
+}
+
static void realm_unmap_private_range(struct kvm *kvm,
unsigned long start,
unsigned long end,
@@ -893,8 +970,21 @@ static int realm_init_ipa_state(struct kvm *kvm,

static int realm_ensure_created(struct kvm *kvm)
{
- /* Provided in later patch */
- return -ENXIO;
+ int ret;
+
+ switch (kvm_realm_state(kvm)) {
+ case REALM_STATE_NONE:
+ break;
+ case REALM_STATE_NEW:
+ return 0;
+ case REALM_STATE_DEAD:
+ return -ENXIO;
+ default:
+ return -EBUSY;
+ }
+
+ ret = realm_create_rd(kvm);
+ return ret;
}

static int set_ripas_of_protected_regions(struct kvm *kvm)
--
2.43.0