[PATCH v2 09/43] arm64: RME: ioctls to create and configure realms

Steven Price
2024-04-12T08:43:39Z

Add the KVM_CAP_ARM_RME_CREATE_FD ioctl to create a realm. This involves
delegating pages to the RMM to hold the Realm Descriptor (RD) and for
the base level of the Realm Translation Tables (RTT). A VMID also need
to be picked, since the RMM has a separate VMID address space a
dedicated allocator is added for this purpose.

KVM_CAP_ARM_RME_CONFIG_REALM is provided to allow configuring the realm
before it is created.

Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
arch/arm64/include/asm/kvm_emulate.h | 5 +
arch/arm64/include/asm/kvm_rme.h | 19 ++
arch/arm64/kvm/arm.c | 18 ++
arch/arm64/kvm/mmu.c | 15 +-
arch/arm64/kvm/rme.c | 282 +++++++++++++++++++++++++++
5 files changed, 337 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 6f08398537e2..c606316f4729 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -624,6 +624,11 @@ static inline enum realm_state kvm_realm_state(struct kvm *kvm)
return READ_ONCE(kvm->arch.realm.state);
}

+static inline bool kvm_realm_is_created(struct kvm *kvm)
+{
+ return kvm_is_realm(kvm) && kvm_realm_state(kvm) != REALM_STATE_NONE;
+}
+
static inline bool vcpu_is_rec(struct kvm_vcpu *vcpu)
{
return false;
diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h
index 922da3f47227..cf8cc4d30364 100644
--- a/arch/arm64/include/asm/kvm_rme.h
+++ b/arch/arm64/include/asm/kvm_rme.h
@@ -6,6 +6,8 @@
#ifndef __ASM_KVM_RME_H
#define __ASM_KVM_RME_H

+#include <uapi/linux/kvm.h>
+
/**
* enum realm_state - State of a Realm
*/
@@ -46,11 +48,28 @@ enum realm_state {
* struct realm - Additional per VM data for a Realm
*
* @state: The lifetime state machine for the realm
+ * @rd: Kernel mapping of the Realm Descriptor (RD)
+ * @params: Parameters for the RMI_REALM_CREATE command
+ * @num_aux: The number of auxiliary pages required by the RMM
+ * @vmid: VMID to be used by the RMM for the realm
+ * @ia_bits: Number of valid Input Address bits in the IPA
*/
struct realm {
enum realm_state state;
+
+ void *rd;
+ struct realm_params *params;
+
+ unsigned long num_aux;
+ unsigned int vmid;
+ unsigned int ia_bits;
};

int kvm_init_rme(void);
+u32 kvm_realm_ipa_limit(void);
+
+int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap);
+int kvm_init_realm_vm(struct kvm *kvm);
+void kvm_destroy_realm(struct kvm *kvm);

#endif
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 2056c660c5ee..5729ea430d6d 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -119,6 +119,13 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
}
mutex_unlock(&kvm->slots_lock);
break;
+ case KVM_CAP_ARM_RME:
+ if (!kvm_is_realm(kvm))
+ return -EINVAL;
+ mutex_lock(&kvm->lock);
+ r = kvm_realm_enable_cap(kvm, cap);
+ mutex_unlock(&kvm->lock);
+ break;
default:
r = -EINVAL;
break;
@@ -179,6 +186,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)

bitmap_zero(kvm->arch.vcpu_features, KVM_VCPU_MAX_FEATURES);

+ /* Initialise the realm bits after the generic bits are enabled */
+ if (kvm_is_realm(kvm)) {
+ ret = kvm_init_realm_vm(kvm);
+ if (ret)
+ goto err_free_cpumask;
+ }
+
return 0;

err_free_cpumask:
@@ -219,6 +233,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
kvm_unshare_hyp(kvm, kvm + 1);

kvm_arm_teardown_hypercalls(kvm);
+ kvm_destroy_realm(kvm);
}

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
@@ -328,6 +343,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES:
r = BIT(0);
break;
+ case KVM_CAP_ARM_RME:
+ r = static_key_enabled(&kvm_rme_is_available);
+ break;
default:
r = 0;
}
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 18680771cdb0..aae365647b62 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -872,6 +872,10 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
struct kvm_pgtable *pgt;
u64 mmfr0, mmfr1;
u32 phys_shift;
+ u32 ipa_limit = kvm_ipa_limit;
+
+ if (kvm_is_realm(kvm))
+ ipa_limit = kvm_realm_ipa_limit();

if (type & ~KVM_VM_TYPE_ARM_IPA_SIZE_MASK)
return -EINVAL;
@@ -880,12 +884,12 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t
if (is_protected_kvm_enabled()) {
phys_shift = kvm_ipa_limit;
} else if (phys_shift) {
- if (phys_shift > kvm_ipa_limit ||
+ if (phys_shift > ipa_limit ||
phys_shift < ARM64_MIN_PARANGE_BITS)
return -EINVAL;
} else {
phys_shift = KVM_PHYS_SHIFT;
- if (phys_shift > kvm_ipa_limit) {
+ if (phys_shift > ipa_limit) {
pr_warn_once("%s using unsupported default IPA limit, upgrade your VMM\n",
current->comm);
return -EINVAL;
@@ -1014,6 +1018,13 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
struct kvm_pgtable *pgt = NULL;

write_lock(&kvm->mmu_lock);
+ if (kvm_is_realm(kvm) &&
+ (kvm_realm_state(kvm) != REALM_STATE_DEAD &&
+ kvm_realm_state(kvm) != REALM_STATE_NONE)) {
+ /* TODO: teardown rtts */
+ write_unlock(&kvm->mmu_lock);
+ return;
+ }
pgt = mmu->pgt;
if (pgt) {
mmu->pgd_phys = 0;
diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c
index 3dbbf9d046bf..658d14e8d87d 100644
--- a/arch/arm64/kvm/rme.c
+++ b/arch/arm64/kvm/rme.c
@@ -5,9 +5,20 @@

#include <linux/kvm_host.h>

+#include <asm/kvm_emulate.h>
+#include <asm/kvm_mmu.h>
#include <asm/rmi_cmds.h>
#include <asm/virt.h>

+#include <asm/kvm_pgtable.h>
+
+static unsigned long rmm_feat_reg0;
+
+static bool rme_supports(unsigned long feature)
+{
+ return !!u64_get_bits(rmm_feat_reg0, feature);
+}
+
static int rmi_check_version(void)
{
struct arm_smccc_res res;
@@ -36,8 +47,272 @@ static int rmi_check_version(void)
return 0;
}

+u32 kvm_realm_ipa_limit(void)
+{
+ return u64_get_bits(rmm_feat_reg0, RMI_FEATURE_REGISTER_0_S2SZ);
+}
+
+static int get_start_level(struct realm *realm)
+{
+ return 4 - stage2_pgtable_levels(realm->ia_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;
+ struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
+ int i, r;
+
+ if (WARN_ON(realm->rd) || WARN_ON(!realm->params))
+ return -EEXIST;
+
+ 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 out;
+ }
+
+ for (i = 0; i < pgt->pgd_pages; i++) {
+ phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+ if (rmi_granule_delegate(pgd_phys)) {
+ r = -ENXIO;
+ goto out_undelegate_tables;
+ }
+ }
+
+ realm->ia_bits = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+
+ params->rtt_level_start = get_start_level(realm);
+ params->rtt_num_start = pgt->pgd_pages;
+ 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;
+ }
+
+ realm->rd = rd;
+
+ if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) {
+ WARN_ON(rmi_realm_destroy(rd_phys));
+ goto out_undelegate_tables;
+ }
+
+ return 0;
+
+out_undelegate_tables:
+ while (--i >= 0) {
+ phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+ WARN_ON(rmi_granule_undelegate(pgd_phys));
+ }
+ WARN_ON(rmi_granule_undelegate(rd_phys));
+out:
+ free_page((unsigned long)rd);
+ return r;
+}
+
+/* Protects access to rme_vmid_bitmap */
+static DEFINE_SPINLOCK(rme_vmid_lock);
+static unsigned long *rme_vmid_bitmap;
+
+static int rme_vmid_init(void)
+{
+ unsigned int vmid_count = 1 << kvm_get_vmid_bits();
+
+ rme_vmid_bitmap = bitmap_zalloc(vmid_count, GFP_KERNEL);
+ if (!rme_vmid_bitmap) {
+ kvm_err("%s: Couldn't allocate rme vmid bitmap\n", __func__);
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int rme_vmid_reserve(void)
+{
+ int ret;
+ unsigned int vmid_count = 1 << kvm_get_vmid_bits();
+
+ spin_lock(&rme_vmid_lock);
+ ret = bitmap_find_free_region(rme_vmid_bitmap, vmid_count, 0);
+ spin_unlock(&rme_vmid_lock);
+
+ return ret;
+}
+
+static void rme_vmid_release(unsigned int vmid)
+{
+ spin_lock(&rme_vmid_lock);
+ bitmap_release_region(rme_vmid_bitmap, vmid, 0);
+ spin_unlock(&rme_vmid_lock);
+}
+
+static int kvm_create_realm(struct kvm *kvm)
+{
+ struct realm *realm = &kvm->arch.realm;
+ int ret;
+
+ if (!kvm_is_realm(kvm) || kvm_realm_is_created(kvm))
+ return -EEXIST;
+
+ ret = rme_vmid_reserve();
+ if (ret < 0)
+ return ret;
+ realm->vmid = ret;
+
+ ret = realm_create_rd(kvm);
+ if (ret) {
+ rme_vmid_release(realm->vmid);
+ return ret;
+ }
+
+ 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;
+}
+
+static int config_realm_hash_algo(struct realm *realm,
+ struct kvm_cap_arm_rme_config_item *cfg)
+{
+ switch (cfg->hash_algo) {
+ case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA256:
+ if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_256))
+ return -EINVAL;
+ break;
+ case KVM_CAP_ARM_RME_MEASUREMENT_ALGO_SHA512:
+ if (!rme_supports(RMI_FEATURE_REGISTER_0_HASH_SHA_512))
+ return -EINVAL;
+ break;
+ default:
+ return -EINVAL;
+ }
+ realm->params->hash_algo = cfg->hash_algo;
+ return 0;
+}
+
+static int kvm_rme_config_realm(struct kvm *kvm, struct kvm_enable_cap *cap)
+{
+ struct kvm_cap_arm_rme_config_item cfg;
+ struct realm *realm = &kvm->arch.realm;
+ int r = 0;
+
+ if (kvm_realm_is_created(kvm))
+ return -EINVAL;
+
+ if (copy_from_user(&cfg, (void __user *)cap->args[1], sizeof(cfg)))
+ return -EFAULT;
+
+ switch (cfg.cfg) {
+ case KVM_CAP_ARM_RME_CFG_RPV:
+ memcpy(&realm->params->rpv, &cfg.rpv, sizeof(cfg.rpv));
+ break;
+ case KVM_CAP_ARM_RME_CFG_HASH_ALGO:
+ r = config_realm_hash_algo(realm, &cfg);
+ break;
+ default:
+ r = -EINVAL;
+ }
+
+ return r;
+}
+
+int kvm_realm_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
+{
+ int r = 0;
+
+ if (!kvm_is_realm(kvm))
+ return -EINVAL;
+
+ switch (cap->args[0]) {
+ case KVM_CAP_ARM_RME_CONFIG_REALM:
+ r = kvm_rme_config_realm(kvm, cap);
+ break;
+ case KVM_CAP_ARM_RME_CREATE_RD:
+ r = kvm_create_realm(kvm);
+ break;
+ default:
+ r = -EINVAL;
+ break;
+ }
+
+ return r;
+}
+
+void kvm_destroy_realm(struct kvm *kvm)
+{
+ struct realm *realm = &kvm->arch.realm;
+ struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
+ int i;
+
+ if (realm->params) {
+ free_page((unsigned long)realm->params);
+ realm->params = NULL;
+ }
+
+ if (!kvm_realm_is_created(kvm))
+ return;
+
+ WRITE_ONCE(realm->state, REALM_STATE_DYING);
+
+ if (realm->rd) {
+ phys_addr_t rd_phys = virt_to_phys(realm->rd);
+
+ if (WARN_ON(rmi_realm_destroy(rd_phys)))
+ return;
+ if (WARN_ON(rmi_granule_undelegate(rd_phys)))
+ return;
+ free_page((unsigned long)realm->rd);
+ realm->rd = NULL;
+ }
+
+ rme_vmid_release(realm->vmid);
+
+ for (i = 0; i < pgt->pgd_pages; i++) {
+ phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE;
+
+ if (WARN_ON(rmi_granule_undelegate(pgd_phys)))
+ return;
+ }
+
+ WRITE_ONCE(realm->state, REALM_STATE_DEAD);
+
+ kvm_free_stage2_pgd(&kvm->arch.mmu);
+}
+
+int kvm_init_realm_vm(struct kvm *kvm)
+{
+ struct realm_params *params;
+
+ params = (struct realm_params *)get_zeroed_page(GFP_KERNEL);
+ if (!params)
+ return -ENOMEM;
+
+ /* Default parameters, not exposed to user space */
+ params->s2sz = VTCR_EL2_IPA(kvm->arch.mmu.vtcr);
+ kvm->arch.realm.params = params;
+ return 0;
+}
+
int kvm_init_rme(void)
{
+ int ret;
+
if (PAGE_SIZE != SZ_4K)
/* Only 4k page size on the host is supported */
return 0;
@@ -46,6 +321,13 @@ int kvm_init_rme(void)
/* Continue without realm support */
return 0;

+ if (WARN_ON(rmi_features(0, &rmm_feat_reg0)))
+ return 0;
+
+ ret = rme_vmid_init();
+ if (ret)
+ return ret;
+
/* Future patch will enable static branch kvm_rme_is_available */

return 0;
--
2.34.1