[PATCH v5 11/13] gunyah: rsc_mgr: Add RPC for console services

[Elliot Berman]

Gunyah resource manager defines a simple API for virtual machine log
sharing with the console service. A VM's own log can be opened by using
GH_VMID_SELF. Another VM's log can be accessed via its VMID. Once
opened, characters can be written to the log with a write command.
Characters are received with resource manager notifications (using ID
GH_RM_NOTIF_VM_CONSOLE_CHARS).

These high level rpc calls are kept in
drivers/virt/gunyah/rsc_mgr_rpc.c. Future RPC calls, e.g. to launch a VM
will also be maintained in this file.

Signed-off-by: Elliot Berman <quic_eberman@xxxxxxxxxxx>
---
 drivers/virt/gunyah/Makefile      |   2 +-
 drivers/virt/gunyah/rsc_mgr.h     |  22 ++++++
 drivers/virt/gunyah/rsc_mgr_rpc.c | 126 ++++++++++++++++++++++++++++++
 include/linux/gunyah_rsc_mgr.h    |  18 +++++
 4 files changed, 167 insertions(+), 1 deletion(-)
 create mode 100644 drivers/virt/gunyah/rsc_mgr_rpc.c

diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index 2cae8ea5bc7d..5eb6ad3c45ba 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -1,5 +1,5 @@
 gunyah-y += gunyah.o
 obj-$(CONFIG_GUNYAH) += gunyah.o
 
-gunyah_rsc_mgr-y += rsc_mgr.o
+gunyah_rsc_mgr-y += rsc_mgr.o rsc_mgr_rpc.o
 obj-$(CONFIG_GUNYAH_RESORUCE_MANAGER) += gunyah_rsc_mgr.o
diff --git a/drivers/virt/gunyah/rsc_mgr.h b/drivers/virt/gunyah/rsc_mgr.h
index e4f2499267bf..4620ac648bcf 100644
--- a/drivers/virt/gunyah/rsc_mgr.h
+++ b/drivers/virt/gunyah/rsc_mgr.h
@@ -28,6 +28,28 @@
 #define GH_RM_ERROR_IRQ_INUSE		0x10
 #define GH_RM_ERROR_IRQ_RELEASED	0x11
 
+/* Message IDs: VM Management */
+#define GH_RM_RPC_VM_GET_VMID			0x56000024
+
+/* Message IDs: VM Services */
+#define GH_RM_RPC_VM_CONSOLE_OPEN_ID		0x56000081
+#define GH_RM_RPC_VM_CONSOLE_CLOSE_ID		0x56000082
+#define GH_RM_RPC_VM_CONSOLE_WRITE_ID		0x56000083
+#define GH_RM_RPC_VM_CONSOLE_FLUSH_ID		0x56000084
+
+/* Call: CONSOLE_OPEN, CONSOLE_CLOSE, CONSOLE_FLUSH */
+struct gh_vm_common_vmid_req {
+	u16 vmid;
+	u16 reserved0;
+} __packed;
+
+/* Call: CONSOLE_WRITE */
+struct gh_vm_console_write_req {
+	u16 vmid;
+	u16 num_bytes;
+	u8 data[0];
+} __packed;
+
 int gh_rm_call(u32 message_id, void *req_buff, size_t req_buff_size,
 		void **resp_buf, size_t *resp_buff_size);
 
diff --git a/drivers/virt/gunyah/rsc_mgr_rpc.c b/drivers/virt/gunyah/rsc_mgr_rpc.c
new file mode 100644
index 000000000000..89d3a295f072
--- /dev/null
+++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
@@ -0,0 +1,126 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#define pr_fmt(fmt) "gh_rsc_mgr: " fmt
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/printk.h>
+#include <linux/gunyah_rsc_mgr.h>
+
+#include "rsc_mgr.h"
+
+/* Several RM calls take only a VMID as a parameter and give only standard response back.
+ * Deduplicate boilerplate code by using this common call.
+ */
+static int gh_rm_common_vmid_call(u32 message_id, u16 vmid)
+{
+	void *resp = NULL;
+	struct gh_vm_common_vmid_req req_payload = {
+		.vmid = vmid,
+	};
+	size_t resp_size;
+	int ret;
+
+	ret = gh_rm_call(message_id, &req_payload, sizeof(req_payload), &resp, &resp_size);
+	if (!ret)
+		kfree(resp);
+
+	WARN_ON(!ret && resp_size);
+
+	return ret;
+}
+
+/**
+ * gh_rm_get_vmid() - Retrieve VMID of this virtual machine
+ * @vmid: Filled with the VMID of this VM
+ */
+int gh_rm_get_vmid(u16 *vmid)
+{
+	void *resp;
+	size_t resp_size;
+	int ret;
+	int payload = 0;
+
+	ret = gh_rm_call(GH_RM_RPC_VM_GET_VMID, &payload, sizeof(payload), &resp, &resp_size);
+	if (ret)
+		return ret;
+
+	if (resp_size != sizeof(*vmid))
+		return -EIO;
+	*vmid = *(u16 *)resp;
+	kfree(resp);
+
+	return ret;
+}
+
+/**
+ * gh_rm_console_open() - Open a console with a VM
+ * @vmid: VMID of the other VM whose console to open. If VMID is GH_VMID_SELF, the
+ *        console associated with this VM is opened.
+ */
+int gh_rm_console_open(u16 vmid)
+{
+	return gh_rm_common_vmid_call(GH_RM_RPC_VM_CONSOLE_OPEN_ID, vmid);
+}
+EXPORT_SYMBOL_GPL(gh_rm_console_open);
+
+/**
+ * gh_rm_console_close() - Close a console with a VM
+ * @vmid: The vmid of the vm whose console to close.
+ */
+int gh_rm_console_close(u16 vmid)
+{
+	return gh_rm_common_vmid_call(GH_RM_RPC_VM_CONSOLE_CLOSE_ID, vmid);
+}
+EXPORT_SYMBOL_GPL(gh_rm_console_close);
+
+/**
+ * gh_rm_console_write() - Write to a VM's console
+ * @vmid: The vmid of the vm whose console to write to.
+ * @buf: Buffer to write to the VM's console
+ * @size: Size of the buffer
+ */
+int gh_rm_console_write(u16 vmid, const char *buf, size_t size)
+{
+	void *resp;
+	struct gh_vm_console_write_req *req_payload;
+	size_t resp_size;
+	int ret = 0;
+	size_t req_payload_size = sizeof(*req_payload) + size;
+
+	if (size < 1 || size > (U32_MAX - sizeof(*req_payload)))
+		return -EINVAL;
+
+	req_payload = kzalloc(req_payload_size, GFP_KERNEL);
+
+	if (!req_payload)
+		return -ENOMEM;
+
+	req_payload->vmid = vmid;
+	req_payload->num_bytes = size;
+	memcpy(req_payload->data, buf, size);
+
+	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_WRITE_ID,
+		   req_payload, req_payload_size,
+		   &resp, &resp_size);
+
+	kfree(req_payload);
+	if (!ret)
+		kfree(resp);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_rm_console_write);
+
+/**
+ * gh_rm_console_flush() - Flush a console with a VM
+ * @vmid: The vmid of the vm whose console to flush
+ */
+int gh_rm_console_flush(u16 vmid)
+{
+	return gh_rm_common_vmid_call(GH_RM_RPC_VM_CONSOLE_FLUSH_ID, vmid);
+}
+EXPORT_SYMBOL_GPL(gh_rm_console_flush);
diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
index b3b37225b7fb..2a1a51299247 100644
--- a/include/linux/gunyah_rsc_mgr.h
+++ b/include/linux/gunyah_rsc_mgr.h
@@ -23,4 +23,22 @@ struct gh_rm_notification {
 int gh_rm_register_notifier(struct notifier_block *nb);
 int gh_rm_unregister_notifier(struct notifier_block *nb);
 
+/* Notification type Message IDs */
+#define GH_RM_NOTIF_VM_CONSOLE_CHARS	0x56100080
+
+struct gh_rm_notif_vm_console_chars {
+	u16 vmid;
+	u16 num_bytes;
+	u8 bytes[];
+} __packed;
+
+/* RPC Calls */
+int gh_rm_get_vmid(u16 *vmid);
+int gh_rm_console_open(u16 vmid);
+int gh_rm_console_close(u16 vmid);
+// Number of characters that can fit in a single RM message.
+#define GH_RM_CONSOLE_WRITE_CHARS	228
+int gh_rm_console_write(u16 vmid, const char *buf, size_t size);
+int gh_rm_console_flush(u16 vmid);
+
 #endif
-- 
2.25.1