crypto: ccp - Add GET_ID SEV command

The GET_ID command, added as of SEV API v0.16, allows the SEV firmware
to be queried about a unique CPU ID. This unique ID can then be used
to obtain the public certificate containing the Chip Endorsement Key
(CEK) public key signed by the AMD SEV Signing Key (ASK).

For more information please refer to "Section 5.12 GET_ID" of
https://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf

Signed-off-by: Janakarajan Natarajan <[e-mail]>
Signed-off-by: Herbert Xu <[e-mail]>

drivers/crypto/ccp/psp-dev.c

···
 	case SEV_CMD_RECEIVE_UPDATE_VMSA:	return sizeof(struct sev_data_receive_update_vmsa);
 	case SEV_CMD_LAUNCH_UPDATE_SECRET:	return sizeof(struct sev_data_launch_secret);
 	case SEV_CMD_DOWNLOAD_FIRMWARE:		return sizeof(struct sev_data_download_firmware);
+	case SEV_CMD_GET_ID:			return sizeof(struct sev_data_get_id);
 	default:				return 0;
 	}
 
···
 	return ret;
 }
 
+static int sev_ioctl_do_get_id(struct sev_issue_cmd *argp)
+{
+	struct sev_data_get_id *data;
+	u64 data_size, user_size;
+	void *id_blob, *mem;
+	int ret;
+
+	/* SEV GET_ID available from SEV API v0.16 and up */
+	if (!SEV_VERSION_GREATER_OR_EQUAL(0, 16))
+		return -ENOTSUPP;
+
+	/* SEV FW expects the buffer it fills with the ID to be
+	 * 8-byte aligned. Memory allocated should be enough to
+	 * hold data structure + alignment padding + memory
+	 * where SEV FW writes the ID.
+	 */
+	data_size = ALIGN(sizeof(struct sev_data_get_id), 8);
+	user_size = sizeof(struct sev_user_data_get_id);
+
+	mem = kzalloc(data_size + user_size, GFP_KERNEL);
+	if (!mem)
+		return -ENOMEM;
+
+	data = mem;
+	id_blob = mem + data_size;
+
+	data->address = __psp_pa(id_blob);
+	data->len = user_size;
+
+	ret = __sev_do_cmd_locked(SEV_CMD_GET_ID, data, &argp->error);
+	if (!ret) {
+		if (copy_to_user((void __user *)argp->data, id_blob, data->len))
+			ret = -EFAULT;
+	}
+
+	kfree(mem);
+
+	return ret;
+}
+
 static int sev_ioctl_do_pdh_export(struct sev_issue_cmd *argp)
 {
 	struct sev_user_data_pdh_cert_export input;
···
 		break;
 	case SEV_PDH_CERT_EXPORT:
 		ret = sev_ioctl_do_pdh_export(&input);
+		break;
+	case SEV_GET_ID:
+		ret = sev_ioctl_do_get_id(&input);
 		break;
 	default:
 		ret = -EINVAL;

include/linux/psp-sev.h

···
 	SEV_CMD_PDH_GEN			= 0x009,
 	SEV_CMD_DF_FLUSH		= 0x00A,
 	SEV_CMD_DOWNLOAD_FIRMWARE	= 0x00B,
+	SEV_CMD_GET_ID			= 0x00C,
 
 	/* Guest commands */
 	SEV_CMD_DECOMMISSION		= 0x020,
···
 	u32 len;				/* In */
 } __packed;
 
+/**
+ * struct sev_data_get_id - GET_ID command parameters
+ *
+ * @address: physical address of region to place unique CPU ID(s)
+ * @len: len of the region
+ */
+struct sev_data_get_id {
+	u64 address;				/* In */
+	u32 len;				/* In/Out */
+} __packed;
 /**
  * struct sev_data_pdh_cert_export - PDH_CERT_EXPORT command parameters
  *

include/uapi/linux/psp-sev.h

···
 	SEV_PDH_GEN,
 	SEV_PDH_CERT_EXPORT,
 	SEV_PEK_CERT_IMPORT,
+	SEV_GET_ID,
 
 	SEV_MAX,
 };
···
 	__u32 pdh_cert_len;			/* In/Out */
 	__u64 cert_chain_address;		/* In */
 	__u32 cert_chain_len;			/* In/Out */
+} __packed;
+
+/**
+ * struct sev_user_data_get_id - GET_ID command parameters
+ *
+ * @socket1: Buffer to pass unique ID of first socket
+ * @socket2: Buffer to pass unique ID of second socket
+ */
+struct sev_user_data_get_id {
+	__u8 socket1[64];			/* Out */
+	__u8 socket2[64];			/* Out */
 } __packed;
 
 /**