Re: [PATCH v7 024/102] KVM: TDX: Add place holder for TDX VM specific mem_enc_op ioctl

Yuan Yao
2022-07-07T07:12:58Z

On Mon, Jun 27, 2022 at 02:53:16PM -0700, isaku.yamahata@intel.com wrote:
> From: Isaku Yamahata <isaku.yamahata@intel.com>
>
> Add a place holder function for TDX specific VM-scoped ioctl as mem_enc_op.
> TDX specific sub-commands will be added to retrieve/pass TDX specific
> parameters.
>
> KVM_MEMORY_ENCRYPT_OP was introduced for VM-scoped operations specific for
> guest state-protected VM. It defined subcommands for technology-specific
> operations under KVM_MEMORY_ENCRYPT_OP. Despite its name, the subcommands
> are not limited to memory encryption, but various technology-specific
> operations are defined. It's natural to repurpose KVM_MEMORY_ENCRYPT_OP
> for TDX specific operations and define subcommands.
>
> TDX requires VM-scoped, and VCPU-scoped TDX-specific operations for device
> model, for example, qemu. Getting system-wide parameters, TDX-specific VM
> initialization, and TDX-specific vCPU initialization. Which requires KVM
> vCPU-scoped operations in addition to the existing VM-scoped operations.

Suggest to no need talking about vcpu scope operations here, because
they're not available in this patch, we can talk about them in the
patch which introduces them.

>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
> arch/x86/kvm/vmx/main.c | 9 +++++++++
> arch/x86/kvm/vmx/tdx.c | 26 ++++++++++++++++++++++++++
> arch/x86/kvm/vmx/x86_ops.h | 4 ++++
> 3 files changed, 39 insertions(+)
>
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index 7b497ed1f21c..067f5de56c53 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -73,6 +73,14 @@ static void vt_vm_free(struct kvm *kvm)
> return tdx_vm_free(kvm);
> }
>
> +static int vt_mem_enc_ioctl(struct kvm *kvm, void __user *argp)
> +{
> + if (!is_td(kvm))
> + return -ENOTTY;
> +
> + return tdx_vm_ioctl(kvm, argp);
> +}
> +
> struct kvm_x86_ops vt_x86_ops __initdata = {
> .name = "kvm_intel",
>
> @@ -214,6 +222,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
> .vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
>
> .dev_mem_enc_ioctl = tdx_dev_ioctl,
> + .mem_enc_ioctl = vt_mem_enc_ioctl,
> };
>
> struct kvm_x86_init_ops vt_init_ops __initdata = {
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index ec4ebba4152a..2a9dfd54189f 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -438,6 +438,32 @@ int tdx_dev_ioctl(void __user *argp)
> return 0;
> }
>
> +int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
> +{
> + struct kvm_tdx_cmd tdx_cmd;
> + int r;
> +
> + if (copy_from_user(&tdx_cmd, argp, sizeof(struct kvm_tdx_cmd)))
> + return -EFAULT;
> + if (tdx_cmd.error || tdx_cmd.unused)
> + return -EINVAL;
> +
> + mutex_lock(&kvm->lock);
> +
> + switch (tdx_cmd.id) {
> + default:
> + r = -EINVAL;
> + goto out;
> + }
> +
> + if (copy_to_user(argp, &tdx_cmd, sizeof(struct kvm_tdx_cmd)))
> + r = -EFAULT;
> +
> +out:
> + mutex_unlock(&kvm->lock);
> + return r;
> +}
> +
> int __init tdx_module_setup(void)
> {
> const struct tdsysinfo_struct *tdsysinfo;
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index 3027d9821fe1..ef6115ae0e88 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -137,6 +137,8 @@ int tdx_dev_ioctl(void __user *argp);
> int tdx_vm_init(struct kvm *kvm);
> void tdx_mmu_release_hkid(struct kvm *kvm);
> void tdx_vm_free(struct kvm *kvm);
> +
> +int tdx_vm_ioctl(struct kvm *kvm, void __user *argp);
> #else
> static inline int tdx_hardware_setup(struct kvm_x86_ops *x86_ops) { return 0; }
> static inline bool tdx_is_vm_type_supported(unsigned long type) { return false; }
> @@ -147,6 +149,8 @@ static inline int tdx_vm_init(struct kvm *kvm) { return -EOPNOTSUPP; }
> static inline void tdx_mmu_release_hkid(struct kvm *kvm) {}
> static inline void tdx_flush_shadow_all_private(struct kvm *kvm) {}
> static inline void tdx_vm_free(struct kvm *kvm) {}
> +
> +static inline int tdx_vm_ioctl(struct kvm *kvm, void __user *argp) { return -EOPNOTSUPP; }
> #endif
>
> #endif /* __KVM_X86_VMX_X86_OPS_H */
> --
> 2.25.1
>