linux-kernel - [PATCH v12 22/46] arm64: RMI: Create the realm descriptor

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20251217101125.91098-23-steven.price@arm.com>
Date: Wed, 17 Dec 2025 10:10:59 +0000
From: Steven Price <steven.price@....com>
To: kvm@...r.kernel.org,
	kvmarm@...ts.linux.dev
Cc: Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>,
	James Morse <james.morse@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Joey Gouly <joey.gouly@....com>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Christoffer Dall <christoffer.dall@....com>,
	Fuad Tabba <tabba@...gle.com>,
	linux-coco@...ts.linux.dev,
	Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>,
	Gavin Shan <gshan@...hat.com>,
	Shanker Donthineni <sdonthineni@...dia.com>,
	Alper Gun <alpergun@...gle.com>,
	"Aneesh Kumar K . V" <aneesh.kumar@...nel.org>,
	Emi Kisanuki <fj0570is@...itsu.com>,
	Vishal Annapurve <vannapurve@...gle.com>
Subject: [PATCH v12 22/46] arm64: RMI: Create the realm descriptor

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@....com>
---
New patch for v12
---
 arch/arm64/kvm/rmi.c | 117 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 115 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
index b51e68e56d56..18edc7eeb5fa 100644
--- a/arch/arm64/kvm/rmi.c
+++ b/arch/arm64/kvm/rmi.c
@@ -500,6 +500,106 @@ static void realm_unmap_shared_range(struct kvm *kvm,
 			     start, end);
 }
 
+/* Calculate the number of s2 root rtts needed */
+static int realm_num_root_rtts(struct realm *realm)
+{
+	unsigned int ipa_bits = realm->ia_bits;
+	unsigned int levels = 4 - get_start_level(realm);
+	unsigned int sl_ipa_bits = levels * (RMM_PAGE_SHIFT - 3) +
+				   RMM_PAGE_SHIFT;
+
+	if (sl_ipa_bits >= ipa_bits)
+		return 1;
+
+	return 1 << (ipa_bits - sl_ipa_bits);
+}
+
+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;
+	int rtt_num_start;
+
+	realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+	rtt_num_start = realm_num_root_rtts(realm);
+
+	if (WARN_ON(realm->rd || !realm->params))
+		return -EEXIST;
+
+	if (pgd_size / RMM_PAGE_SIZE < rtt_num_start)
+		return -EINVAL;
+
+	rd = (void *)__get_free_page(GFP_KERNEL);
+	if (!rd)
+		return -ENOMEM;
+
+	rd_phys = virt_to_phys(rd);
+	if (rmi_granule_delegate(rd_phys)) {
+		r = -ENXIO;
+		goto free_rd;
+	}
+
+	for (i = 0; i < pgd_size; i += RMM_PAGE_SIZE) {
+		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i;
+
+		if (rmi_granule_delegate(pgd_phys)) {
+			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 = rtt_num_start;
+	params->rtt_base = kvm->arch.mmu.pgd_phys;
+	params->vmid = realm->vmid;
+
+	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:
+	while (i > 0) {
+		i -= RMM_PAGE_SIZE;
+
+		phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i;
+
+		if (WARN_ON(rmi_granule_undelegate(pgd_phys))) {
+			/* Leak the pages if they cannot be returned */
+			kvm->arch.mmu.pgt = NULL;
+			break;
+		}
+	}
+	if (WARN_ON(rmi_granule_undelegate(rd_phys))) {
+		/* Leak the page if it isn't returned */
+		return r;
+	}
+free_rd:
+	free_page((unsigned long)rd);
+	return r;
+}
+
 static int realm_unmap_private_page(struct realm *realm,
 				    unsigned long ipa,
 				    unsigned long *next_addr)
@@ -803,8 +903,21 @@ 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