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

Gavin Shan
2025-03-03T04:10:52Z

On 2/14/25 2:13 AM, Steven Price wrote:
> 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(+)
>

The newly added ioctl commands need to be documented in Documentation/virt/kvm/api.rst.
Section 4 would be the right place for it. Other than that, it looks good to me except
the ioctl commands need to be fixed as suggested by Aneesh.

Thanks,
Gavin

> 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 */