[RFC PATCH v2 01/11] KVM: SVM: Add KVM_SEV SEND_START command

["Singh, Brijesh" <brijesh.singh@amd.com>]

The command is used to create an outgoing SEV guest encryption context.

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
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
---
 .../virtual/kvm/amd-memory-encryption.rst     |  27 +++++
 arch/x86/kvm/svm.c                            | 105 ++++++++++++++++++
 include/uapi/linux/kvm.h                      |  12 ++
 3 files changed, 144 insertions(+)

diff --git a/Documentation/virtual/kvm/amd-memory-encryption.rst b/Documentation/virtual/kvm/amd-memory-encryption.rst
index 659bbc093b52..9ea974c87980 100644
--- a/Documentation/virtual/kvm/amd-memory-encryption.rst
+++ b/Documentation/virtual/kvm/amd-memory-encryption.rst
@@ -238,6 +238,33 @@ Returns: 0 on success, -negative on error
                 __u32 trans_len;
         };
 
+10. KVM_SEV_SEND_START
+----------------------
+
+The KVM_SEV_SEND_START command can be used by the hypervisor to create an
+outgoing guest encryption context.
+
+Parameters (in): struct kvm_sev_send_start
+
+Returns: 0 on success, -negative on error
+
+::
+        struct kvm_sev_send_start {
+                __u32 policy;                 /* guest policy */
+
+                __u64 pdh_cert_uaddr;         /* platform Diffie-Hellman certificate */
+                __u32 pdh_cert_len;
+
+                __u64 plat_cert_uaddr;        /* platform certificate chain */
+                __u32 plat_cert_len;
+
+                __u64 amd_cert_uaddr;         /* AMD certificate */
+                __u32 amd_cert_len;
+
+                __u64 session_uaddr;         /* Guest session information */
+                __u32 session_len;
+        };
+
 References
 ==========
 
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 735b8c01895e..98e5a6c2bacc 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -6960,6 +6960,108 @@ static int sev_launch_secret(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	return ret;
 }
 
+static int sev_send_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
+{
+	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
+	void *amd_cert = NULL, *session_data = NULL;
+	void *pdh_cert = NULL, *plat_cert = NULL;
+	struct sev_data_send_start *data = NULL;
+	struct kvm_sev_send_start params;
+	int ret;
+
+	if (!sev_guest(kvm))
+		return -ENOTTY;
+
+	if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
+				sizeof(struct kvm_sev_send_start)))
+		return -EFAULT;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	/* userspace wants to query the session length */
+	if (!params.session_len)
+		goto cmd;
+
+	if (!params.pdh_cert_uaddr || !params.pdh_cert_len ||
+	    !params.session_uaddr)
+		return -EINVAL;
+
+	/* copy the certificate blobs from userspace */
+	pdh_cert = psp_copy_user_blob(params.pdh_cert_uaddr, params.pdh_cert_len);
+	if (IS_ERR(pdh_cert)) {
+		ret = PTR_ERR(pdh_cert);
+		goto e_free;
+	}
+
+	data->pdh_cert_address = __psp_pa(pdh_cert);
+	data->pdh_cert_len = params.pdh_cert_len;
+
+	plat_cert = psp_copy_user_blob(params.plat_cert_uaddr, params.plat_cert_len);
+	if (IS_ERR(plat_cert)) {
+		ret = PTR_ERR(plat_cert);
+		goto e_free_pdh;
+	}
+
+	data->plat_cert_address = __psp_pa(plat_cert);
+	data->plat_cert_len = params.plat_cert_len;
+
+	amd_cert = psp_copy_user_blob(params.amd_cert_uaddr, params.amd_cert_len);
+	if (IS_ERR(amd_cert)) {
+		ret = PTR_ERR(amd_cert);
+		goto e_free_plat_cert;
+	}
+
+	data->amd_cert_address = __psp_pa(amd_cert);
+	data->amd_cert_len = params.amd_cert_len;
+
+	ret = -EINVAL;
+	if (params.session_len > SEV_FW_BLOB_MAX_SIZE)
+		goto e_free_amd_cert;
+
+	ret = -ENOMEM;
+	session_data = kmalloc(params.session_len, GFP_KERNEL);
+	if (!session_data)
+		goto e_free_amd_cert;
+
+	data->session_address = __psp_pa(session_data);
+	data->session_len = params.session_len;
+cmd:
+	data->handle = sev->handle;
+	ret = sev_issue_cmd(kvm, SEV_CMD_SEND_START, data, &argp->error);
+
+	/* if we queried the session length, FW responded with expected data */
+	if (!params.session_len)
+		goto done;
+
+	if (copy_to_user((void __user *)(uintptr_t) params.session_uaddr,
+			session_data, params.session_len)) {
+		ret = -EFAULT;
+		goto e_free_session;
+	}
+
+	params.policy = data->policy;
+
+done:
+	params.session_len = data->session_len;
+	if (copy_to_user((void __user *)(uintptr_t)argp->data, &params,
+				sizeof(struct kvm_sev_send_start)))
+		ret = -EFAULT;
+
+e_free_session:
+	kfree(session_data);
+e_free_amd_cert:
+	kfree(amd_cert);
+e_free_plat_cert:
+	kfree(plat_cert);
+e_free_pdh:
+	kfree(pdh_cert);
+e_free:
+	kfree(data);
+	return ret;
+}
+
 static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 {
 	struct kvm_sev_cmd sev_cmd;
@@ -7001,6 +7103,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
 	case KVM_SEV_LAUNCH_SECRET:
 		r = sev_launch_secret(kvm, &sev_cmd);
 		break;
+	case KVM_SEV_SEND_START:
+		r = sev_send_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 2fe12b40d503..4e9e7a5b2066 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1531,6 +1531,18 @@ struct kvm_sev_dbg {
 	__u32 len;
 };
 
+struct kvm_sev_send_start {
+	__u32 policy;
+	__u64 pdh_cert_uaddr;
+	__u32 pdh_cert_len;
+	__u64 plat_cert_uaddr;
+	__u32 plat_cert_len;
+	__u64 amd_cert_uaddr;
+	__u32 amd_cert_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