[PATCH v7 07/45] arm64: RME: Define the user ABI

Steven Price
2025-02-13T16:15:15Z

There is one (multiplexed) CAP which can be used to create, populate and
then activate the realm.

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>
---
Changes since v6:
* Rename some of the symbols to make their usage clearer and avoid
repetition.
Changes from v5:
* Actually expose the new VCPU capability (KVM_ARM_VCPU_REC) by bumping
KVM_VCPU_MAX_FEATURES - note this also exposes KVM_ARM_VCPU_HAS_EL2!
---
Documentation/virt/kvm/api.rst | 1 +
arch/arm64/include/uapi/asm/kvm.h | 49 +++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 12 ++++++++
3 files changed, 62 insertions(+)

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 0d1c3a820ce6..06763d89c0d7 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -5094,6 +5094,7 @@ Recognised values for feature:

===== ===========================================
arm64 KVM_ARM_VCPU_SVE (requires KVM_CAP_ARM_SVE)
+ arm64 KVM_ARM_VCPU_REC (requires KVM_CAP_ARM_RME)
===== ===========================================

Finalizes the configuration of the specified vcpu feature.
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 568bf858f319..7eae0b1a482e 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -105,6 +105,7 @@ struct kvm_regs {
#define KVM_ARM_VCPU_PTRAUTH_ADDRESS 5 /* VCPU uses address authentication */
#define KVM_ARM_VCPU_PTRAUTH_GENERIC 6 /* VCPU uses generic authentication */
#define KVM_ARM_VCPU_HAS_EL2 7 /* Support nested virtualization */
+#define KVM_ARM_VCPU_REC 8 /* VCPU REC state as part of Realm */

struct kvm_vcpu_init {
__u32 target;
@@ -415,6 +416,54 @@ enum {
#define KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES 3
#define KVM_DEV_ARM_ITS_CTRL_RESET 4

+/* KVM_CAP_ARM_RME on VM fd */
+#define KVM_CAP_ARM_RME_CONFIG_REALM 0
+#define KVM_CAP_ARM_RME_CREATE_REALM 1
+#define KVM_CAP_ARM_RME_INIT_RIPAS_REALM 2
+#define KVM_CAP_ARM_RME_POPULATE_REALM 3
+#define KVM_CAP_ARM_RME_ACTIVATE_REALM 4
+
+/* List of configuration items accepted for KVM_CAP_ARM_RME_CONFIG_REALM */
+#define ARM_RME_CONFIG_RPV 0
+#define ARM_RME_CONFIG_HASH_ALGO 1
+
+#define ARM_RME_CONFIG_MEASUREMENT_ALGO_SHA256 0
+#define ARM_RME_CONFIG_MEASUREMENT_ALGO_SHA512 1
+
+#define ARM_RME_CONFIG_RPV_SIZE 64
+
+struct arm_rme_config {
+ __u32 cfg;
+ union {
+ /* cfg == ARM_RME_CONFIG_RPV */
+ struct {
+ __u8 rpv[ARM_RME_CONFIG_RPV_SIZE];
+ };
+
+ /* cfg == ARM_RME_CONFIG_HASH_ALGO */
+ struct {
+ __u32 hash_algo;
+ };
+
+ /* Fix the size of the union */
+ __u8 reserved[256];
+ };
+};
+
+#define KVM_ARM_RME_POPULATE_FLAGS_MEASURE (1 << 0)
+struct arm_rme_populate_realm {
+ __u64 base;
+ __u64 size;
+ __u32 flags;
+ __u32 reserved[3];
+};
+
+struct arm_rme_init_ripas {
+ __u64 base;
+ __u64 size;
+ __u64 reserved[2];
+};
+
/* Device Control API on vcpu fd */
#define KVM_ARM_VCPU_PMU_V3_CTRL 0
#define KVM_ARM_VCPU_PMU_V3_IRQ 0
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 45e6d8fca9b9..fa8f45029dff 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -930,6 +930,8 @@ struct kvm_enable_cap {
#define KVM_CAP_X86_APIC_BUS_CYCLES_NS 237
#define KVM_CAP_X86_GUEST_MODE 238

+#define KVM_CAP_ARM_RME 300 /* FIXME: Large number to prevent conflicts */
+
struct kvm_irq_routing_irqchip {
__u32 irqchip;
__u32 pin;
@@ -1581,4 +1583,14 @@ struct kvm_pre_fault_memory {
__u64 padding[5];
};

+/* Available with KVM_CAP_ARM_RME, only for VMs with KVM_VM_TYPE_ARM_REALM */
+struct kvm_arm_rmm_psci_complete {
+ __u64 target_mpidr;
+ __u32 psci_status;
+ __u32 padding[3];
+};
+
+/* FIXME: Update nr (0xd2) when merging */
+#define KVM_ARM_VCPU_RMM_PSCI_COMPLETE _IOW(KVMIO, 0xd2, struct kvm_arm_rmm_psci_complete)
+
#endif /* __LINUX_KVM_H */
--
2.43.0