hv: vm_event: create vm_event support

This patch creates vm_event support in HV, including:
1. Create vm_event data type.
2. Add vm_event sbuf and its initializer. The sbuf will be allocated by
   DM in Service VM. Its page address will then be share to HV through
   hypercall.
3. Add an API to send the HV generated event.

Tracked-On: #8547
Signed-off-by: Wu Zhou <wu.zhou@intel.com>
Reviewed-by: Junjie Mao <junjie.mao@intel.com>

hypervisor/Makefile

@@ -236,6 +236,7 @@ HW_C_SRCS += common/schedule.c
 HW_C_SRCS += common/event.c
 HW_C_SRCS += common/efi_mmap.c
 HW_C_SRCS += common/sbuf.c
+HW_C_SRCS += common/vm_event.c
 ifeq ($(CONFIG_SCHED_NOOP),y)
 HW_C_SRCS += common/sched_noop.c
 endif

hypervisor/arch/x86/guest/vm.c

@@ -787,6 +787,8 @@ int32_t create_vm(uint16_t vm_id, uint64_t pcpu_bitmap, struct acrn_vm_config *v
 		passthrough_smbios(vm, get_acrn_boot_info());
 #endif
 
+		vm->sw.vm_event_sbuf = NULL;
+
 		status = init_vpci(vm);
 		if (status == 0) {
 			enable_iommu();

hypervisor/common/sbuf.c

@@ -14,6 +14,7 @@
 #include <errno.h>
 #include <asm/cpu.h>
 #include <asm/per_cpu.h>
+#include <vm_event.h>
 
 uint32_t sbuf_next_ptr(uint32_t pos_arg,
 		uint32_t span, uint32_t scope)
@@ -93,6 +94,9 @@ int32_t sbuf_setup_common(struct acrn_vm *vm, uint16_t cpu_id, uint32_t sbuf_id,
 		case ACRN_ASYNCIO:
 			ret = init_asyncio(vm, hva);
 			break;
+		case ACRN_VM_EVENT:
+			ret = init_vm_event(vm, hva);
+			break;
 		default:
 			pr_err("%s not support sbuf_id %d", __func__, sbuf_id);
 			ret = -1;

hypervisor/common/vm_event.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2020-2023 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <errno.h>
+#include <util.h>
+#include <acrn_hv_defs.h>
+#include <asm/guest/vm.h>
+#include <vm_event.h>
+#include <sbuf.h>
+
+int32_t init_vm_event(struct acrn_vm *vm, uint64_t *hva)
+{
+	struct shared_buf *sbuf = (struct shared_buf *)hva;
+	int ret = -1;
+
+	stac();
+	if (sbuf != NULL) {
+		if (sbuf->magic == SBUF_MAGIC) {
+			vm->sw.vm_event_sbuf = sbuf;
+			spinlock_init(&vm->vm_event_lock);
+			ret = 0;
+		}
+	}
+	clac();
+
+	return ret;
+}
+
+int32_t send_vm_event(struct acrn_vm *vm, struct vm_event *event)
+{
+	struct shared_buf *sbuf = (struct shared_buf *)vm->sw.vm_event_sbuf;
+	int32_t ret = -ENODEV;
+	uint32_t size_sent;
+
+	if (sbuf != NULL) {
+		spinlock_obtain(&vm->vm_event_lock);
+		size_sent = sbuf_put(sbuf, (uint8_t *)event);
+		spinlock_release(&vm->vm_event_lock);
+		if (size_sent == sizeof(struct vm_event)) {
+			arch_fire_hsm_interrupt();
+			ret = 0;
+		}
+	}
+	return ret;
+}

hypervisor/include/arch/x86/asm/guest/vm.h

@@ -71,6 +71,7 @@ struct vm_sw_info {
 	/* HVA to IO shared page */
 	void *io_shared_page;
 	void *asyncio_sbuf;
+	void *vm_event_sbuf;
 	/* If enable IO completion polling mode */
 	bool is_polling_ioreq;
 };
@@ -146,6 +147,7 @@ struct acrn_vm {
 	struct asyncio_desc	aio_desc[ACRN_ASYNCIO_MAX];
 	struct list_head aiodesc_queue;
 	spinlock_t asyncio_lock; /* Spin-lock used to protect asyncio add/remove for a VM */
+	spinlock_t vm_event_lock;
 
 	enum vpic_wire_mode wire_mode;
 	struct iommu_domain *iommu;	/* iommu domain of this VM */

hypervisor/include/common/vm_event.h

@@ -0,0 +1,16 @@
+/*
+ * Copyright (C) 2019-2023 Intel Corporation.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef VM_EVENT_H
+#define VM_EVENT_H
+
+#include <types.h>
+#include <acrn_common.h>
+
+int32_t init_vm_event(struct acrn_vm *vm, uint64_t *hva);
+int32_t send_vm_event(struct acrn_vm *vm, struct vm_event *event);
+
+#endif /* VM_EVENT_H */

hypervisor/include/public/acrn_common.h

@@ -776,6 +776,7 @@ enum {
 	/* The sbuf with above ids are created each pcpu */
 	ACRN_SBUF_PER_PCPU_ID_MAX,
 	ACRN_ASYNCIO = 64,
+	ACRN_VM_EVENT,
 };
 
 /* Make sure sizeof(struct shared_buf) == SBUF_HEAD_SIZE */
@@ -792,6 +793,53 @@ struct shared_buf {
 	uint32_t padding[6];
 };
 
+/**
+ * VM event architecture:
+ * +------------------------------------------------------+
+ * |    Service VM                                        |
+ * | +----------------------------+                       |
+ * | | DM  +--------------------+ |                       |
+ * | |     | [ event source ]   | |                       |
+ * | |     +-+------------+-----+ |                       |
+ * | |       | (eventfd)  |(sbuf) |                       |
+ * | |       v            v       |                       |
+ * | | +------------------------+ | (socket)  +---------+ |
+ * | | |  [event deliver logic] |-+---------->| Libvirt | |
+ * | | +------------------------+ |           +---------+ |
+ * | |       ^            ^       |                       |
+ * | +-------|------------|-------+                       |
+ * |         | (eventfd)  | (sbuf)                        |
+ * +---------|------------|-------------------------------+
+ * +---------|------------|-------------------------------+
+ * | kernel [HSM]         |                               |
+ * |         ^            |                               |
+ * +---------|------------|-------------------------------+
+ *           |upcall      |
+ * +---------+------------+-------------------------------+
+ * | HV     [ event source ]                              |
+ * +------------------------------------------------------+
+ *
+ * For event sources in HV
+ *  - HV puts the event in the shared ring sbuf.
+ *  - The hypervisor notifies the service VM via upcall.
+ *  - HSM in the service VM notifies device model via eventfd.
+ *  - The device model fetches and handles events from the shared ring sbuf.
+ * For event sources in DM
+ *  - DM puts the event in the DM event ring sbuf.
+ *  - DM notifies event delivery logic via eventfd.
+ *  - The event delivery logic fetches and handles events from the DM event ring sbuf.
+ */
+#define VM_EVENT_RTC_CHG	0U
+#define VM_EVENT_POWEROFF	1U
+#define VM_EVENT_TRIPLE_FAULT	2U
+
+#define VM_EVENT_DATA_LEN	28U
+
+struct vm_event {
+    uint32_t type;
+    uint8_t event_data[VM_EVENT_DATA_LEN];
+};
+
 /**
  * @}
  */