linux-kernel - Re: [RFC PATCH v5 061/104] KVM: TDX: Finalize VM initialization

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Message-ID: <d95791fc-a278-9002-2f12-6aeaa1d1e47f@redhat.com>
Date:   Fri, 15 Apr 2022 15:52:14 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     isaku.yamahata@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...il.com, Jim Mattson <jmattson@...gle.com>,
        erdemaktas@...gle.com, Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: Re: [RFC PATCH v5 061/104] KVM: TDX: Finalize VM initialization

On 3/4/22 20:49, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> To protect the initial contents of the guest TD, the TDX module measures
> the guest TD during the build process as SHA-384 measurement.  The
> measurement of the guest TD contents needs to be completed to make the
> guest TD ready to run.
> 
> Add a new subcommand, KVM_TDX_FINALIZE_VM, for VM-scoped
> KVM_MEMORY_ENCRYPT_OP to finalize the measurement and mark the TDX VM ready
> to run.
> 
> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>   arch/x86/include/uapi/asm/kvm.h       |  1 +
>   arch/x86/kvm/vmx/tdx.c                | 21 +++++++++++++++++++++
>   tools/arch/x86/include/uapi/asm/kvm.h |  1 +
>   3 files changed, 23 insertions(+)
> 
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 77f46260d868..943219a08fcd 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -534,6 +534,7 @@ enum kvm_tdx_cmd_id {
>   	KVM_TDX_INIT_VM,
>   	KVM_TDX_INIT_VCPU,
>   	KVM_TDX_INIT_MEM_REGION,
> +	KVM_TDX_FINALIZE_VM,
>   
>   	KVM_TDX_CMD_NR_MAX,
>   };
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index cd726c41d362..85d5f961d97e 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -1103,6 +1103,24 @@ static int tdx_init_mem_region(struct kvm *kvm, struct kvm_tdx_cmd *cmd)
>   	return ret;
>   }
>   
> +static int tdx_td_finalizemr(struct kvm *kvm)
> +{
> +	struct kvm_tdx *kvm_tdx = to_kvm_tdx(kvm);
> +	u64 err;
> +
> +	if (!is_td_initialized(kvm) || is_td_finalized(kvm_tdx))
> +		return -EINVAL;
> +
> +	err = tdh_mr_finalize(kvm_tdx->tdr.pa);
> +	if (WARN_ON_ONCE(err)) {
> +		pr_tdx_error(TDH_MR_FINALIZE, err, NULL);
> +		return -EIO;
> +	}
> +
> +	kvm_tdx->finalized = true;
> +	return 0;
> +}
> +
>   int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
>   {
>   	struct kvm_tdx_cmd tdx_cmd;
> @@ -1123,6 +1141,9 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
>   	case KVM_TDX_INIT_MEM_REGION:
>   		r = tdx_init_mem_region(kvm, &tdx_cmd);
>   		break;
> +	case KVM_TDX_FINALIZE_VM:
> +		r = tdx_td_finalizemr(kvm);
> +		break;
>   	default:
>   		r = -EINVAL;
>   		goto out;
> diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
> index 77f46260d868..943219a08fcd 100644
> --- a/tools/arch/x86/include/uapi/asm/kvm.h
> +++ b/tools/arch/x86/include/uapi/asm/kvm.h
> @@ -534,6 +534,7 @@ enum kvm_tdx_cmd_id {
>   	KVM_TDX_INIT_VM,
>   	KVM_TDX_INIT_VCPU,
>   	KVM_TDX_INIT_MEM_REGION,
> +	KVM_TDX_FINALIZE_VM,
>   
>   	KVM_TDX_CMD_NR_MAX,
>   };

Reviewed-by: Paolo Bonzini <pbonzini@...hat.com>

Note however that errors should be passed back in the struct.

Paolo