[PATCH v2 10/11] 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      |   4 +-
 drivers/virt/gunyah/rsc_mgr.h     |  22 +++++
 drivers/virt/gunyah/rsc_mgr_rpc.c | 151 ++++++++++++++++++++++++++++++
 include/linux/gunyah_rsc_mgr.h    |  16 ++++
 4 files changed, 191 insertions(+), 2 deletions(-)
 create mode 100644 drivers/virt/gunyah/rsc_mgr_rpc.c

diff --git a/drivers/virt/gunyah/Makefile b/drivers/virt/gunyah/Makefile
index 86655bca8944..b3f15c052297 100644
--- a/drivers/virt/gunyah/Makefile
+++ b/drivers/virt/gunyah/Makefile
@@ -1,5 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 gunyah-y += sysfs.o device.o msgq.o
-gunyah-y += rsc_mgr.o
-obj-$(CONFIG_GUNYAH) += gunyah.o
\ No newline at end of file
+gunyah-y += rsc_mgr.o rsc_mgr_rpc.o
+obj-$(CONFIG_GUNYAH) += gunyah.o
diff --git a/drivers/virt/gunyah/rsc_mgr.h b/drivers/virt/gunyah/rsc_mgr.h
index e4f2499267bf..c82a2e97ad49 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_console_common_req {
+	gh_vmid_t vmid;
+	u16 reserved0;
+} __packed;
+
+/* Call: CONSOLE_WRITE */
+struct gh_vm_console_write_req {
+	gh_vmid_t 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..be9317968537
--- /dev/null
+++ b/drivers/virt/gunyah/rsc_mgr_rpc.c
@@ -0,0 +1,151 @@
+// 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"
+
+/**
+ * gh_rm_get_vmid: Retrieve VMID of this virtual machine
+ * @vmid: Filled with the VMID of this VM
+ */
+int gh_rm_get_vmid(gh_vmid_t *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 = *(gh_vmid_t *)resp;
+	kfree(resp);
+
+	return ret;
+}
+
+/**
+ * gh_rm_console_open: Open a console with a VM
+ * @vmid: VMID of the other vmid whose console to open. If VMID is GH_VMID_SELF, the
+ *        console associated with this VM is opened.
+ */
+int gh_rm_console_open(gh_vmid_t vmid)
+{
+	void *resp;
+	struct gh_vm_console_common_req req_payload = {0};
+	size_t resp_size;
+	int ret;
+
+	req_payload.vmid = vmid;
+
+	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_OPEN_ID,
+			  &req_payload, sizeof(req_payload),
+			  &resp, &resp_size);
+	kfree(resp);
+
+	if (!ret && resp_size)
+		pr_warn("Received unexpected payload for CONSOLE_OPEN: %lu\n", resp_size);
+
+	return ret;
+}
+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(gh_vmid_t vmid)
+{
+	void *resp;
+	struct gh_vm_console_common_req req_payload = {0};
+	size_t resp_size;
+	int ret;
+
+	req_payload.vmid = vmid;
+
+	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_CLOSE_ID,
+			  &req_payload, sizeof(req_payload),
+			  &resp, &resp_size);
+	kfree(resp);
+
+	if (!ret && resp_size)
+		pr_warn("Received unexpected payload for CONSOLE_CLOSE: %lu\n", resp_size);
+
+	return ret;
+}
+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(gh_vmid_t 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);
+	kfree(resp);
+
+	if (!ret && resp_size)
+		pr_warn("Received unexpected payload for CONSOLE_WRITE: %lu\n", resp_size);
+
+	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(gh_vmid_t vmid)
+{
+	void *resp;
+	struct gh_vm_console_common_req req_payload = {0};
+	size_t resp_size;
+	int ret;
+
+	req_payload.vmid = vmid;
+
+	ret = gh_rm_call(GH_RM_RPC_VM_CONSOLE_FLUSH_ID,
+			  &req_payload, sizeof(req_payload),
+			  &resp, &resp_size);
+	kfree(resp);
+
+	if (!ret && resp_size)
+		pr_warn("Received unexpected payload for CONSOLE_FLUSH: %lu\n", resp_size);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gh_rm_console_flush);
diff --git a/include/linux/gunyah_rsc_mgr.h b/include/linux/gunyah_rsc_mgr.h
index 015bd851e1a3..4211ac9a219c 100644
--- a/include/linux/gunyah_rsc_mgr.h
+++ b/include/linux/gunyah_rsc_mgr.h
@@ -26,4 +26,20 @@ 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 {
+	gh_vmid_t vmid;
+	u16 num_bytes;
+	u8 bytes[0];
+} __packed;
+
+/* RPC Calls */
+int gh_rm_get_vmid(gh_vmid_t *vmid);
+int gh_rm_console_open(gh_vmid_t vmid);
+int gh_rm_console_close(gh_vmid_t vmid);
+int gh_rm_console_write(gh_vmid_t vmid, const char *buf, size_t size);
+int gh_rm_console_flush(gh_vmid_t vmid);
+
 #endif
-- 
2.25.1