Re: [PATCH v4 16/21] KVM: arm64: Support SDEI ioctl commands on VM

Eric Auger
2021-11-10T13:48:27Z

On 8/15/21 2:13 AM, Gavin Shan wrote:
> This supports ioctl commands on VM to manage the various objects.
> It's primarily used by VMM to accomplish live migration. The ioctl
> commands introduced by this are highlighted as blow:
below
>
> * KVM_SDEI_CMD_GET_VERSION
> Retrieve the version of current implementation
which implementation, SDEI?
> * KVM_SDEI_CMD_SET_EVENT
> Add event to be exported from KVM so that guest can register
> against it afterwards
> * KVM_SDEI_CMD_GET_KEVENT_COUNT
> Retrieve number of registered SDEI events
> * KVM_SDEI_CMD_GET_KEVENT
> Retrieve the state of the registered SDEI event
> * KVM_SDEI_CMD_SET_KEVENT
> Populate the registered SDEI event
I think we really miss the full picture of what you want to achieve with
those IOCTLs or at least I fail to get it. Please document the UAPI
separately including the structs and IOCTLs.
>
> Signed-off-by: Gavin Shan <gshan@redhat.com>
> ---
> arch/arm64/include/asm/kvm_sdei.h | 1 +
> arch/arm64/include/uapi/asm/kvm_sdei.h | 17 +++
> arch/arm64/kvm/arm.c | 3 +
> arch/arm64/kvm/sdei.c | 171 +++++++++++++++++++++++++
> include/uapi/linux/kvm.h | 3 +
> 5 files changed, 195 insertions(+)
>
> diff --git a/arch/arm64/include/asm/kvm_sdei.h b/arch/arm64/include/asm/kvm_sdei.h
> index 19f2d9b91f85..8f5ea947ed0e 100644
> --- a/arch/arm64/include/asm/kvm_sdei.h
> +++ b/arch/arm64/include/asm/kvm_sdei.h
> @@ -125,6 +125,7 @@ int kvm_sdei_hypercall(struct kvm_vcpu *vcpu);
> int kvm_sdei_register_notifier(struct kvm *kvm, unsigned long num,
> kvm_sdei_notifier notifier);
> void kvm_sdei_deliver(struct kvm_vcpu *vcpu);
> +long kvm_sdei_vm_ioctl(struct kvm *kvm, unsigned long arg);
> void kvm_sdei_destroy_vcpu(struct kvm_vcpu *vcpu);
> void kvm_sdei_destroy_vm(struct kvm *kvm);
>
> diff --git a/arch/arm64/include/uapi/asm/kvm_sdei.h b/arch/arm64/include/uapi/asm/kvm_sdei.h
> index 4ef661d106fe..35ff05be3c28 100644
> --- a/arch/arm64/include/uapi/asm/kvm_sdei.h
> +++ b/arch/arm64/include/uapi/asm/kvm_sdei.h
> @@ -57,5 +57,22 @@ struct kvm_sdei_vcpu_state {
> struct kvm_sdei_vcpu_regs normal_regs;
> };
>
> +#define KVM_SDEI_CMD_GET_VERSION 0
> +#define KVM_SDEI_CMD_SET_EVENT 1
> +#define KVM_SDEI_CMD_GET_KEVENT_COUNT 2
> +#define KVM_SDEI_CMD_GET_KEVENT 3
> +#define KVM_SDEI_CMD_SET_KEVENT 4
> +
> +struct kvm_sdei_cmd {
> + __u32 cmd;
> + union {
> + __u32 version;
> + __u32 count;
> + __u64 num;
> + struct kvm_sdei_event_state kse_state;
> + struct kvm_sdei_kvm_event_state kske_state;
> + };
> +};
> +
> #endif /* !__ASSEMBLY__ */
> #endif /* _UAPI__ASM_KVM_SDEI_H */
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 0c3db1ef1ba9..8d61585124b2 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -1389,6 +1389,9 @@ long kvm_arch_vm_ioctl(struct file *filp,
> return -EFAULT;
> return kvm_vm_ioctl_mte_copy_tags(kvm, &copy_tags);
> }
> + case KVM_ARM_SDEI_COMMAND: {
> + return kvm_sdei_vm_ioctl(kvm, arg);
> + }
> default:
> return -EINVAL;
> }
> diff --git a/arch/arm64/kvm/sdei.c b/arch/arm64/kvm/sdei.c
> index 5f7a37dcaa77..bdd76c3e5153 100644
> --- a/arch/arm64/kvm/sdei.c
> +++ b/arch/arm64/kvm/sdei.c
> @@ -931,6 +931,177 @@ void kvm_sdei_create_vcpu(struct kvm_vcpu *vcpu)
> vcpu->arch.sdei = vsdei;
> }
>
> +static long kvm_sdei_set_event(struct kvm *kvm,
> + struct kvm_sdei_event_state *kse_state)
> +{
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_event *kse = NULL;
> +
> + if (!kvm_sdei_is_valid_event_num(kse_state->num))
> + return -EINVAL;
> +
> + if (!(kse_state->type == SDEI_EVENT_TYPE_SHARED ||
> + kse_state->type == SDEI_EVENT_TYPE_PRIVATE))
> + return -EINVAL;
> +
> + if (!(kse_state->priority == SDEI_EVENT_PRIORITY_NORMAL ||
> + kse_state->priority == SDEI_EVENT_PRIORITY_CRITICAL))
> + return -EINVAL;
> +
> + kse = kvm_sdei_find_event(kvm, kse_state->num);
> + if (kse)
> + return -EEXIST;
> +
> + kse = kzalloc(sizeof(*kse), GFP_KERNEL);
> + if (!kse)
> + return -ENOMEM;
userspace can exhaust the mem since there is no limit. There must be a max.

> +
> + kse->state = *kse_state;
> + kse->kvm = kvm;
> + list_add_tail(&kse->link, &ksdei->events);
> +
> + return 0;
> +}
> +
> +static long kvm_sdei_get_kevent_count(struct kvm *kvm, int *count)
> +{
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_kvm_event *kske = NULL;
> + int total = 0;
> +
> + list_for_each_entry(kske, &ksdei->kvm_events, link) {
> + total++;
> + }
> +
> + *count = total;
> + return 0;
> +}
> +
> +static long kvm_sdei_get_kevent(struct kvm *kvm,
> + struct kvm_sdei_kvm_event_state *kske_state)
> +{
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_kvm_event *kske = NULL;
> +
> + /*
> + * The first entry is fetched if the event number is invalid.
> + * Otherwise, the next entry is fetched.
why don't we return an error? What is the point returning the next entry?
> + */
> + if (!kvm_sdei_is_valid_event_num(kske_state->num)) {
> + kske = list_first_entry_or_null(&ksdei->kvm_events,
> + struct kvm_sdei_kvm_event, link);
> + } else {
> + kske = kvm_sdei_find_kvm_event(kvm, kske_state->num);
> + if (kske && !list_is_last(&kske->link, &ksdei->kvm_events))
> + kske = list_next_entry(kske, link);
Sorry I don't get why we return the next one?
> + else
> + kske = NULL;
> + }
> +
> + if (!kske)
> + return -ENOENT;
> +
> + *kske_state = kske->state;
> +
> + return 0;
> +}
> +
> +static long kvm_sdei_set_kevent(struct kvm *kvm,
> + struct kvm_sdei_kvm_event_state *kske_state)
> +{
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_event *kse = NULL;
> + struct kvm_sdei_kvm_event *kske = NULL;
> +
> + /* Sanity check */
> + if (!kvm_sdei_is_valid_event_num(kske_state->num))
> + return -EINVAL;
> +
> + if (!(kske_state->route_mode == SDEI_EVENT_REGISTER_RM_ANY ||
> + kske_state->route_mode == SDEI_EVENT_REGISTER_RM_PE))
> + return -EINVAL;
> +
> + /* Check if the event number is valid */
> + kse = kvm_sdei_find_event(kvm, kske_state->num);
> + if (!kse)
> + return -ENOENT;
> +
> + /* Check if the event has been populated */
> + kske = kvm_sdei_find_kvm_event(kvm, kske_state->num);
> + if (kske)
> + return -EEXIST;
> +
> + kske = kzalloc(sizeof(*kske), GFP_KERNEL);
userspace can exhaust the mem since there is no limit
> + if (!kske)
> + return -ENOMEM;
> +
> + kske->state = *kske_state;
> + kske->kse = kse;
> + kske->kvm = kvm;
> + list_add_tail(&kske->link, &ksdei->kvm_events);
> +
> + return 0;
> +}
> +
> +long kvm_sdei_vm_ioctl(struct kvm *kvm, unsigned long arg)
> +{
> + struct kvm_sdei_kvm *ksdei = kvm->arch.sdei;
> + struct kvm_sdei_cmd *cmd = NULL;
> + void __user *argp = (void __user *)arg;
> + bool copy = false;
> + long ret = 0;
> +
> + /* Sanity check */
> + if (!ksdei) {
> + ret = -EPERM;
> + goto out;
> + }
> +
> + cmd = kzalloc(sizeof(*cmd), GFP_KERNEL);
> + if (!cmd) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + if (copy_from_user(cmd, argp, sizeof(*cmd))) {
> + ret = -EFAULT;
> + goto out;
> + }
> +
> + spin_lock(&ksdei->lock);
> +
> + switch (cmd->cmd) {
> + case KVM_SDEI_CMD_GET_VERSION:
> + copy = true;
> + cmd->version = (1 << 16); /* v1.0.0 */
> + break;
> + case KVM_SDEI_CMD_SET_EVENT:
> + ret = kvm_sdei_set_event(kvm, &cmd->kse_state);
> + break;
> + case KVM_SDEI_CMD_GET_KEVENT_COUNT:
> + copy = true;
> + ret = kvm_sdei_get_kevent_count(kvm, &cmd->count);
> + break;
> + case KVM_SDEI_CMD_GET_KEVENT:
> + copy = true;
> + ret = kvm_sdei_get_kevent(kvm, &cmd->kske_state);
> + break;
> + case KVM_SDEI_CMD_SET_KEVENT:
> + ret = kvm_sdei_set_kevent(kvm, &cmd->kske_state);
> + break;
> + default:
> + ret = -EINVAL;
> + }
> +
> + spin_unlock(&ksdei->lock);
> +out:
> + if (!ret && copy && copy_to_user(argp, cmd, sizeof(*cmd)))
> + ret = -EFAULT;
> +
> + kfree(cmd);
> + return ret;
> +}
> +
> void kvm_sdei_destroy_vcpu(struct kvm_vcpu *vcpu)
> {
> struct kvm_sdei_vcpu *vsdei = vcpu->arch.sdei;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index d9e4aabcb31a..8cf41fd4bf86 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1679,6 +1679,9 @@ struct kvm_xen_vcpu_attr {
> #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_DATA 0x4
> #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST 0x5
>
> +/* Available with KVM_CAP_ARM_SDEI */
> +#define KVM_ARM_SDEI_COMMAND _IOWR(KVMIO, 0xce, struct kvm_sdei_cmd)
> +
> /* Secure Encrypted Virtualization command */
> enum sev_cmd_id {
> /* Guest initialization commands */
>
Eric