linux-kernel - Re: [PATCH v6 06/14] KVM: SVM: Add KVM_SEV_RECEIVE

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Date:   Thu, 2 Apr 2020 17:24:57 -0500
From:   Venu Busireddy <venu.busireddy@...cle.com>
To:     Ashish Kalra <Ashish.Kalra@....com>
Cc:     pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        hpa@...or.com, joro@...tes.org, bp@...e.de,
        thomas.lendacky@....com, x86@...nel.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, rientjes@...gle.com,
        srutherford@...gle.com, luto@...nel.org, brijesh.singh@....com
Subject: Re: [PATCH v6 06/14] KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command

On 2020-03-30 06:21:36 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@....com>
> 
> The command finalize the guest receiving process and make the SEV guest
> ready for the execution.
> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: "H. Peter Anvin" <hpa@...or.com>
> Cc: Paolo Bonzini <pbonzini@...hat.com>
> Cc: "Radim Krčmář" <rkrcmar@...hat.com>
> Cc: Joerg Roedel <joro@...tes.org>
> Cc: Borislav Petkov <bp@...e.de>
> Cc: Tom Lendacky <thomas.lendacky@....com>
> Cc: x86@...nel.org
> Cc: kvm@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@....com>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>  .../virt/kvm/amd-memory-encryption.rst        |  8 +++++++
>  arch/x86/kvm/svm.c                            | 23 +++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index 554aa33a99cc..93cd95d9a6c0 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -375,6 +375,14 @@ Returns: 0 on success, -negative on error
>                  __u32 trans_len;
>          };
>  
> +15. KVM_SEV_RECEIVE_FINISH
> +------------------------
> +
> +After completion of the migration flow, the KVM_SEV_RECEIVE_FINISH command can be
> +issued by the hypervisor to make the guest ready for execution.
> +
> +Returns: 0 on success, -negative on error
> +
>  References
>  ==========
>  
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 5fc5355536d7..7c2721e18b06 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -7573,6 +7573,26 @@ static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  	return ret;
>  }
>  
> +static int sev_receive_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> +	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> +	struct sev_data_receive_finish *data;
> +	int ret;
> +
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;

Noticed this in earlier patches too. Is -ENOTTY the best return value?
Aren't one of -ENXIO, or -ENODEV, or -EINVAL a better choice? What is
the rationale for using -ENOTTY?

> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->handle = sev->handle;
> +	ret = sev_issue_cmd(kvm, SEV_CMD_RECEIVE_FINISH, data, &argp->error);
> +
> +	kfree(data);
> +	return ret;
> +}
> +
>  static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  {
>  	struct kvm_sev_cmd sev_cmd;
> @@ -7632,6 +7652,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
>  	case KVM_SEV_RECEIVE_UPDATE_DATA:
>  		r = sev_receive_update_data(kvm, &sev_cmd);
>  		break;
> +	case KVM_SEV_RECEIVE_FINISH:
> +		r = sev_receive_finish(kvm, &sev_cmd);
> +		break;
>  	default:
>  		r = -EINVAL;
>  		goto out;
> -- 
> 2.17.1
>