Re: [PATCH v8 04/18] KVM: SVM: Add support for KVM_SEV_RECEIVE_START command

Venu Busireddy
2020-05-05T22:55:19Z

On 2020-05-05 21:15:40 +0000, Ashish Kalra wrote:
> From: Brijesh Singh <Brijesh.Singh@amd.com>
>
> The command is used to create the encryption context for an incoming
> SEV guest. The encryption context can be later used by the hypervisor
> to import the incoming data into the SEV guest memory space.
>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Radim Krčmář" <rkrcmar@redhat.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Cc: Borislav Petkov <bp@suse.de>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: x86@kernel.org
> Cc: kvm@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Reviewed-by: Steve Rutherford <srutherford@google.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>

Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>

> ---
> .../virt/kvm/amd-memory-encryption.rst | 29 +++++++
> arch/x86/kvm/svm/sev.c | 81 +++++++++++++++++++
> include/uapi/linux/kvm.h | 9 +++
> 3 files changed, 119 insertions(+)
>
> diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> index 93884ec8918e..337bf6a8a3ee 100644
> --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> @@ -322,6 +322,35 @@ issued by the hypervisor to delete the encryption context.
>
> Returns: 0 on success, -negative on error
>
> +13. KVM_SEV_RECEIVE_START
> +------------------------
> +
> +The KVM_SEV_RECEIVE_START command is used for creating the memory encryption
> +context for an incoming SEV guest. To create the encryption context, the user must
> +provide a guest policy, the platform public Diffie-Hellman (PDH) key and session
> +information.
> +
> +Parameters: struct kvm_sev_receive_start (in/out)
> +
> +Returns: 0 on success, -negative on error
> +
> +::
> +
> + struct kvm_sev_receive_start {
> + __u32 handle; /* if zero then firmware creates a new handle */
> + __u32 policy; /* guest's policy */
> +
> + __u64 pdh_uaddr; /* userspace address pointing to the PDH key */
> + __u32 pdh_len;
> +
> + __u64 session_uaddr; /* userspace address which points to the guest session information */
> + __u32 session_len;
> + };
> +
> +On success, the 'handle' field contains a new handle and on error, a negative value.
> +
> +For more details, see SEV spec Section 6.12.
> +
> References
> ==========
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 4d3031c9fdcf..b575aa8e27af 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -1173,6 +1173,84 @@ static int sev_send_finish(struct kvm *kvm, struct kvm_sev_cmd *argp)
> return ret;
> }
>
> +static int sev_receive_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> +{
> + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> + struct sev_data_receive_start *start;
> + struct kvm_sev_receive_start params;
> + int *error = &argp->error;
> + void *session_data;
> + void *pdh_data;
> + int ret;
> +
> + if (!sev_guest(kvm))
> + return -ENOTTY;
> +
> + /* Get parameter from the userspace */
> + if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> + sizeof(struct kvm_sev_receive_start)))
> + return -EFAULT;
> +
> + /* some sanity checks */
> + if (!params.pdh_uaddr || !params.pdh_len ||
> + !params.session_uaddr || !params.session_len)
> + return -EINVAL;
> +
> + pdh_data = psp_copy_user_blob(params.pdh_uaddr, params.pdh_len);
> + if (IS_ERR(pdh_data))
> + return PTR_ERR(pdh_data);
> +
> + session_data = psp_copy_user_blob(params.session_uaddr,
> + params.session_len);
> + if (IS_ERR(session_data)) {
> + ret = PTR_ERR(session_data);
> + goto e_free_pdh;
> + }
> +
> + ret = -ENOMEM;
> + start = kzalloc(sizeof(*start), GFP_KERNEL);
> + if (!start)
> + goto e_free_session;
> +
> + start->handle = params.handle;
> + start->policy = params.policy;
> + start->pdh_cert_address = __psp_pa(pdh_data);
> + start->pdh_cert_len = params.pdh_len;
> + start->session_address = __psp_pa(session_data);
> + start->session_len = params.session_len;
> +
> + /* create memory encryption context */
> + ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_RECEIVE_START, start,
> + error);
> + if (ret)
> + goto e_free;
> +
> + /* Bind ASID to this guest */
> + ret = sev_bind_asid(kvm, start->handle, error);
> + if (ret)
> + goto e_free;
> +
> + params.handle = start->handle;
> + if (copy_to_user((void __user *)(uintptr_t)argp->data,
> + &params, sizeof(struct kvm_sev_receive_start))) {
> + ret = -EFAULT;
> + sev_unbind_asid(kvm, start->handle);
> + goto e_free;
> + }
> +
> + sev->handle = start->handle;
> + sev->fd = argp->sev_fd;
> +
> +e_free:
> + kfree(start);
> +e_free_session:
> + kfree(session_data);
> +e_free_pdh:
> + kfree(pdh_data);
> +
> + return ret;
> +}
> +
> int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> {
> struct kvm_sev_cmd sev_cmd;
> @@ -1226,6 +1304,9 @@ int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> case KVM_SEV_SEND_FINISH:
> r = sev_send_finish(kvm, &sev_cmd);
> break;
> + case KVM_SEV_RECEIVE_START:
> + r = sev_receive_start(kvm, &sev_cmd);
> + break;
> default:
> r = -EINVAL;
> goto out;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 7aaed8ee33cf..24ac57151d53 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1619,6 +1619,15 @@ struct kvm_sev_send_update_data {
> __u32 trans_len;
> };
>
> +struct kvm_sev_receive_start {
> + __u32 handle;
> + __u32 policy;
> + __u64 pdh_uaddr;
> + __u32 pdh_len;
> + __u64 session_uaddr;
> + __u32 session_len;
> +};
> +
> #define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
> #define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)
> #define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)
> --
> 2.17.1
>