Re: [PATCH v7 06/18] KVM: SVM: Add KVM_SEV_RECEIVE_FINISH command

From: Venu Busireddy
Date: Mon May 04 2020 - 17:42:09 EST


On 2020-04-30 08:42:37 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@xxxxxxx>
>
> The command finalize the guest receiving process and make the SEV guest
> ready for the execution.
>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Cc: x86@xxxxxxxxxx
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Reviewed-by: Steve Rutherford <srutherford@xxxxxxxxxx>
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
> ---
> .../virt/kvm/amd-memory-encryption.rst | 8 +++++++
> arch/x86/kvm/svm/sev.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/sev.c b/arch/x86/kvm/svm/sev.c
> index d5dfd0da53b9..1f9181e37ef0 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1327,6 +1327,26 @@ 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;

What is the rationale for using -ENOTTY? Is it the best return
value? Aren't one of -ENXIO, or -ENODEV, or -EINVAL a better choice?

> +
> + 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;
> +}
> +
> int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> {
> struct kvm_sev_cmd sev_cmd;
> @@ -1386,6 +1406,9 @@ 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
>