linux-kernel - Re: [PATCH v8 022/103] KVM: TDX: Add place holder for TDX VM specific mem_enc

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Message-ID: <20220831021825.6uevl3xkvwog47ht@yy-desk-7060>
Date:   Wed, 31 Aug 2022 10:18:25 +0800
From:   Yuan Yao <yuan.yao@...ux.intel.com>
To:     isaku.yamahata@...el.com
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
        erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>
Subject: Re: [PATCH v8 022/103] KVM: TDX: Add place holder for TDX VM
 specific mem_enc_op ioctl

On Sun, Aug 07, 2022 at 03:01:07PM -0700, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.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 TDX-specific operations for device model, for
> example, qemu.  Getting system-wide parameters, TDX-specific VM
> initialization.
>
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.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 16c6570dbe52..d3b9f653da4b 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -424,6 +424,32 @@ 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)))

Minor: sizeof(tdx_cmd), escape from type change & better readability.

> +		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)))

Ditto

> +		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 02490515d190..f0fe40c7ac34 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
>