[PATCH v6 09/18] virt: acrn: Introduce I/O request management

shuo.a.liu
2020-12-01T09:41:47Z

An I/O request of a User VM, which is constructed by the hypervisor, is
distributed by the ACRN Hypervisor Service Module to an I/O client
corresponding to the address range of the I/O request.

For each User VM, there is a shared 4-KByte memory region used for I/O
requests communication between the hypervisor and Service VM. An I/O
request is a 256-byte structure buffer, which is 'struct
acrn_io_request', that is filled by an I/O handler of the hypervisor
when a trapped I/O access happens in a User VM. ACRN userspace in the
Service VM first allocates a 4-KByte page and passes the GPA (Guest
Physical Address) of the buffer to the hypervisor. The buffer is used as
an array of 16 I/O request slots with each I/O request slot being 256
bytes. This array is indexed by vCPU ID.

An I/O client, which is 'struct acrn_ioreq_client', is responsible for
handling User VM I/O requests whose accessed GPA falls in a certain
range. Multiple I/O clients can be associated with each User VM. There
is a special client associated with each User VM, called the default
client, that handles all I/O requests that do not fit into the range of
any other I/O clients. The ACRN userspace acts as the default client for
each User VM.

The state transitions of a ACRN I/O request are as follows.

FREE -> PENDING -> PROCESSING -> COMPLETE -> FREE -> ...

FREE: this I/O request slot is empty
PENDING: a valid I/O request is pending in this slot
PROCESSING: the I/O request is being processed
COMPLETE: the I/O request has been processed

An I/O request in COMPLETE or FREE state is owned by the hypervisor. HSM
and ACRN userspace are in charge of processing the others.

The processing flow of I/O requests are listed as following:

a) The I/O handler of the hypervisor will fill an I/O request with
PENDING state when a trapped I/O access happens in a User VM.
b) The hypervisor makes an upcall, which is a notification interrupt, to
the Service VM.
c) The upcall handler schedules a tasklet to dispatch I/O requests.
d) The tasklet looks for the PENDING I/O requests, assigns them to
different registered clients based on the address of the I/O accesses,
updates their state to PROCESSING, and notifies the corresponding
client to handle.
e) The notified client handles the assigned I/O requests.
f) The HSM updates I/O requests states to COMPLETE and notifies the
hypervisor of the completion via hypercalls.

Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/virt/acrn/Makefile | 2 +-
drivers/virt/acrn/acrn_drv.h | 82 ++++++
drivers/virt/acrn/hsm.c | 34 ++-
drivers/virt/acrn/hypercall.h | 28 ++
drivers/virt/acrn/ioreq.c | 509 ++++++++++++++++++++++++++++++++++
drivers/virt/acrn/vm.c | 27 +-
include/uapi/linux/acrn.h | 134 +++++++++
7 files changed, 806 insertions(+), 10 deletions(-)
create mode 100644 drivers/virt/acrn/ioreq.c

diff --git a/drivers/virt/acrn/Makefile b/drivers/virt/acrn/Makefile
index 38bc44b6edcd..21721cbf6a80 100644
--- a/drivers/virt/acrn/Makefile
+++ b/drivers/virt/acrn/Makefile
@@ -1,3 +1,3 @@
# SPDX-License-Identifier: GPL-2.0
obj-$(CONFIG_ACRN_HSM) := acrn.o
-acrn-y := hsm.o vm.o mm.o
+acrn-y := hsm.o vm.o mm.o ioreq.o
diff --git a/drivers/virt/acrn/acrn_drv.h b/drivers/virt/acrn/acrn_drv.h
index e47a45280eea..7e89e4944d0f 100644
--- a/drivers/virt/acrn/acrn_drv.h
+++ b/drivers/virt/acrn/acrn_drv.h
@@ -12,10 +12,15 @@

extern struct miscdevice acrn_dev;

+#define ACRN_NAME_LEN 16
#define ACRN_MEM_MAPPING_MAX 256

#define ACRN_MEM_REGION_ADD 0
#define ACRN_MEM_REGION_DEL 2
+
+struct acrn_vm;
+struct acrn_ioreq_client;
+
/**
* struct vm_memory_region_op - Hypervisor memory operation
* @type: Operation type (ACRN_MEM_REGION_*)
@@ -75,9 +80,63 @@ struct vm_memory_mapping {
size_t size;
};

+/**
+ * struct acrn_ioreq_buffer - Data for setting the ioreq buffer of User VM
+ * @ioreq_buf: The GPA of the IO request shared buffer of a VM
+ *
+ * The parameter for the HC_SET_IOREQ_BUFFER hypercall used to set up
+ * the shared I/O request buffer between Service VM and ACRN hypervisor.
+ */
+struct acrn_ioreq_buffer {
+ u64 ioreq_buf;
+};
+
+struct acrn_ioreq_range {
+ struct list_head list;
+ u32 type;
+ u64 start;
+ u64 end;
+};
+
+#define ACRN_IOREQ_CLIENT_DESTROYING 0U
+typedef int (*ioreq_handler_t)(struct acrn_ioreq_client *client,
+ struct acrn_io_request *req);
+/**
+ * struct acrn_ioreq_client - Structure of I/O client.
+ * @name: Client name
+ * @vm: The VM that the client belongs to
+ * @list: List node for this acrn_ioreq_client
+ * @is_default: If this client is the default one
+ * @flags: Flags (ACRN_IOREQ_CLIENT_*)
+ * @range_list: I/O ranges
+ * @range_lock: Lock to protect range_list
+ * @ioreqs_map: The pending I/O requests bitmap.
+ * @handler: I/O requests handler of this client
+ * @thread: The thread which executes the handler
+ * @wq: The wait queue for the handler thread parking
+ * @priv: Data for the thread
+ */
+struct acrn_ioreq_client {
+ char name[ACRN_NAME_LEN];
+ struct acrn_vm *vm;
+ struct list_head list;
+ bool is_default;
+ unsigned long flags;
+ struct list_head range_list;
+ rwlock_t range_lock;
+ DECLARE_BITMAP(ioreqs_map, ACRN_IO_REQUEST_MAX);
+ ioreq_handler_t handler;
+ struct task_struct *thread;
+ wait_queue_head_t wq;
+ void *priv;
+};
+
#define ACRN_INVALID_VMID (0xffffU)

#define ACRN_VM_FLAG_DESTROYED 0U
+#define ACRN_VM_FLAG_CLEARING_IOREQ 1U
+extern struct list_head acrn_vm_list;
+extern rwlock_t acrn_vm_list_lock;
/**
* struct acrn_vm - Properties of ACRN User VM.
* @list: Entry within global list of all VMs.
@@ -90,6 +149,11 @@ struct vm_memory_mapping {
* &acrn_vm.regions_mapping_count.
* @regions_mapping: Memory mappings of this VM.
* @regions_mapping_count: Number of memory mapping of this VM.
+ * @ioreq_clients_lock: Lock to protect ioreq_clients and default_client
+ * @ioreq_clients: The I/O request clients list of this VM
+ * @default_client: The default I/O request client
+ * @ioreq_buf: I/O request shared buffer
+ * @ioreq_page: The page of the I/O request shared buffer
*/
struct acrn_vm {
struct list_head list;
@@ -99,6 +163,11 @@ struct acrn_vm {
struct mutex regions_mapping_lock;
struct vm_memory_mapping regions_mapping[ACRN_MEM_MAPPING_MAX];
int regions_mapping_count;
+ spinlock_t ioreq_clients_lock;
+ struct list_head ioreq_clients;
+ struct acrn_ioreq_client *default_client;
+ struct acrn_io_request_buffer *ioreq_buf;
+ struct page *ioreq_page;
};

struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
@@ -112,4 +181,17 @@ int acrn_vm_memseg_unmap(struct acrn_vm *vm, struct acrn_vm_memmap *memmap);
int acrn_vm_ram_map(struct acrn_vm *vm, struct acrn_vm_memmap *memmap);
void acrn_vm_all_ram_unmap(struct acrn_vm *vm);

+int acrn_ioreq_init(struct acrn_vm *vm, u64 buf_vma);
+void acrn_ioreq_deinit(struct acrn_vm *vm);
+void acrn_ioreq_intr_setup(void);
+void acrn_ioreq_intr_remove(void);
+void acrn_ioreq_request_clear(struct acrn_vm *vm);
+int acrn_ioreq_client_wait(struct acrn_ioreq_client *client);
+int acrn_ioreq_request_default_complete(struct acrn_vm *vm, u16 vcpu);
+struct acrn_ioreq_client *acrn_ioreq_client_create(struct acrn_vm *vm,
+ ioreq_handler_t handler,
+ void *data, bool is_default,
+ const char *name);
+void acrn_ioreq_client_destroy(struct acrn_ioreq_client *client);
+
#endif /* __ACRN_HSM_DRV_H */
diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
index 3d76ab27cf89..ea86be0ab5e4 100644
--- a/drivers/virt/acrn/hsm.c
+++ b/drivers/virt/acrn/hsm.c
@@ -48,6 +48,7 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
struct acrn_vm *vm = filp->private_data;
struct acrn_vm_creation *vm_param;
struct acrn_vcpu_regs *cpu_regs;
+ struct acrn_ioreq_notify notify;
struct acrn_vm_memmap memmap;
int ret = 0;

@@ -130,6 +131,31 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,

ret = acrn_vm_memseg_unmap(vm, &memmap);
break;
+ case ACRN_IOCTL_CREATE_IOREQ_CLIENT:
+ if (vm->default_client)
+ return -EEXIST;
+ if (!acrn_ioreq_client_create(vm, NULL, NULL, true, "acrndm"))
+ ret = -EINVAL;
+ break;
+ case ACRN_IOCTL_DESTROY_IOREQ_CLIENT:
+ if (vm->default_client)
+ acrn_ioreq_client_destroy(vm->default_client);
+ break;
+ case ACRN_IOCTL_ATTACH_IOREQ_CLIENT:
+ if (vm->default_client)
+ ret = acrn_ioreq_client_wait(vm->default_client);
+ else
+ ret = -ENODEV;
+ break;
+ case ACRN_IOCTL_NOTIFY_REQUEST_FINISH:
+ if (copy_from_user(&notify, (void __user *)ioctl_param,
+ sizeof(struct acrn_ioreq_notify)))
+ return -EFAULT;
+ ret = acrn_ioreq_request_default_complete(vm, notify.vcpu);
+ break;
+ case ACRN_IOCTL_CLEAR_VM_IOREQ:
+ acrn_ioreq_request_clear(vm);
+ break;
default:
dev_dbg(acrn_dev.this_device, "Unknown IOCTL 0x%x!\n", cmd);
ret = -ENOTTY;
@@ -171,14 +197,18 @@ static int __init hsm_init(void)
return -EPERM;

ret = misc_register(&acrn_dev);
- if (ret)
+ if (ret) {
pr_err("Create misc dev failed!\n");
+ return ret;
+ }

- return ret;
+ acrn_ioreq_intr_setup();
+ return 0;
}

static void __exit hsm_exit(void)
{
+ acrn_ioreq_intr_remove();
misc_deregister(&acrn_dev);
}
module_init(hsm_init);
diff --git a/drivers/virt/acrn/hypercall.h b/drivers/virt/acrn/hypercall.h
index a1a70a071713..5eba29e3ed38 100644
--- a/drivers/virt/acrn/hypercall.h
+++ b/drivers/virt/acrn/hypercall.h
@@ -21,6 +21,10 @@
#define HC_RESET_VM _HC_ID(HC_ID, HC_ID_VM_BASE + 0x05)
#define HC_SET_VCPU_REGS _HC_ID(HC_ID, HC_ID_VM_BASE + 0x06)

+#define HC_ID_IOREQ_BASE 0x30UL
+#define HC_SET_IOREQ_BUFFER _HC_ID(HC_ID, HC_ID_IOREQ_BASE + 0x00)
+#define HC_NOTIFY_REQUEST_FINISH _HC_ID(HC_ID, HC_ID_IOREQ_BASE + 0x01)
+
#define HC_ID_MEM_BASE 0x40UL
#define HC_VM_SET_MEMORY_REGIONS _HC_ID(HC_ID, HC_ID_MEM_BASE + 0x02)

@@ -91,6 +95,30 @@ static inline long hcall_set_vcpu_regs(u64 vmid, u64 regs_state)
return acrn_hypercall2(HC_SET_VCPU_REGS, vmid, regs_state);
}

+/**
+ * hcall_set_ioreq_buffer() - Set up the shared buffer for I/O Requests.
+ * @vmid: User VM ID
+ * @buffer: Service VM GPA of the shared buffer
+ *
+ * Return: 0 on success, <0 on failure
+ */
+static inline long hcall_set_ioreq_buffer(u64 vmid, u64 buffer)
+{
+ return acrn_hypercall2(HC_SET_IOREQ_BUFFER, vmid, buffer);
+}
+
+/**
+ * hcall_notify_req_finish() - Notify ACRN Hypervisor of I/O request completion.
+ * @vmid: User VM ID
+ * @vcpu: The vCPU which initiated the I/O request
+ *
+ * Return: 0 on success, <0 on failure
+ */
+static inline long hcall_notify_req_finish(u64 vmid, u64 vcpu)
+{
+ return acrn_hypercall2(HC_NOTIFY_REQUEST_FINISH, vmid, vcpu);
+}
+
/**
* hcall_set_memory_regions() - Inform the hypervisor to set up EPT mappings
* @regions_pa: Service VM GPA of &struct vm_memory_region_batch
diff --git a/drivers/virt/acrn/ioreq.c b/drivers/virt/acrn/ioreq.c
new file mode 100644
index 000000000000..ed22b1c4775d
--- /dev/null
+++ b/drivers/virt/acrn/ioreq.c
@@ -0,0 +1,509 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ACRN_HSM: Handle I/O requests
+ *
+ * Copyright (C) 2020 Intel Corporation. All rights reserved.
+ *
+ * Authors:
+ * Jason Chen CJ <jason.cj.chen@intel.com>
+ * Fengwei Yin <fengwei.yin@intel.com>
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kthread.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+
+#include <asm/acrn.h>
+
+#include "acrn_drv.h"
+
+static void ioreq_pause(void);
+static void ioreq_resume(void);
+
+static struct tasklet_struct ioreq_tasklet;
+
+static inline bool has_pending_request(struct acrn_ioreq_client *client)
+{
+ return !bitmap_empty(client->ioreqs_map, ACRN_IO_REQUEST_MAX);
+}
+
+static inline bool is_destroying(struct acrn_ioreq_client *client)
+{
+ return test_bit(ACRN_IOREQ_CLIENT_DESTROYING, &client->flags);
+}
+
+static int ioreq_complete_request(struct acrn_vm *vm, u16 vcpu,
+ struct acrn_io_request *acrn_req)
+{
+ bool polling_mode;
+ int ret = 0;
+
+ polling_mode = acrn_req->completion_polling;
+ /* Add barrier() to make sure the writes are done before completion */
+ smp_store_release(&acrn_req->processed, ACRN_IOREQ_STATE_COMPLETE);
+
+ /*
+ * To fulfill the requirement of real-time in several industry
+ * scenarios, like automotive, ACRN can run under the partition mode,
+ * in which User VMs and Service VM are bound to dedicated CPU cores.
+ * Polling mode of handling the I/O request is introduced to achieve a
+ * faster I/O request handling. In polling mode, the hypervisor polls
+ * I/O request's completion. Once an I/O request is marked as
+ * ACRN_IOREQ_STATE_COMPLETE, hypervisor resumes from the polling point
+ * to continue the I/O request flow. Thus, the completion notification
+ * from HSM of I/O request is not needed. Please note,
+ * completion_polling needs to be read before the I/O request being
+ * marked as ACRN_IOREQ_STATE_COMPLETE to avoid racing with the
+ * hypervisor.
+ */
+ if (!polling_mode) {
+ ret = hcall_notify_req_finish(vm->vmid, vcpu);
+ if (ret < 0)
+ dev_err(acrn_dev.this_device,
+ "Notify I/O request finished failed!\n");
+ }
+
+ return ret;
+}
+
+static int acrn_ioreq_complete_request(struct acrn_ioreq_client *client,
+ u16 vcpu,
+ struct acrn_io_request *acrn_req)
+{
+ int ret;
+
+ if (vcpu >= client->vm->vcpu_num)
+ return -EINVAL;
+
+ clear_bit(vcpu, client->ioreqs_map);
+ if (!acrn_req) {
+ acrn_req = (struct acrn_io_request *)client->vm->ioreq_buf;
+ acrn_req += vcpu;
+ }
+
+ ret = ioreq_complete_request(client->vm, vcpu, acrn_req);
+
+ return ret;
+}
+
+int acrn_ioreq_request_default_complete(struct acrn_vm *vm, u16 vcpu)
+{
+ int ret = 0;
+
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ if (vm->default_client)
+ ret = acrn_ioreq_complete_request(vm->default_client,
+ vcpu, NULL);
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+
+ return ret;
+}
+
+/*
+ * ioreq_task() is the execution entity of handler thread of an I/O client.
+ * The handler callback of the I/O client is called within the handler thread.
+ */
+static int ioreq_task(void *data)
+{
+ struct acrn_ioreq_client *client = data;
+ struct acrn_io_request *req;
+ unsigned long *ioreqs_map;
+ int vcpu, ret;
+
+ /*
+ * Lockless access to ioreqs_map is safe, because
+ * 1) set_bit() and clear_bit() are atomic operations.
+ * 2) I/O requests arrives serialized. The access flow of ioreqs_map is:
+ * set_bit() - in tasklet
+ * Handler callback handles corresponding I/O request
+ * clear_bit() - in handler thread (include ACRN userspace)
+ * Mark corresponding I/O request completed
+ * Loop again if a new I/O request occurs
+ */
+ ioreqs_map = client->ioreqs_map;
+ while (!kthread_should_stop()) {
+ acrn_ioreq_client_wait(client);
+ while (has_pending_request(client)) {
+ vcpu = find_first_bit(ioreqs_map, client->vm->vcpu_num);
+ req = client->vm->ioreq_buf->req_slot + vcpu;
+ ret = client->handler(client, req);
+ if (ret < 0) {
+ dev_err(acrn_dev.this_device,
+ "IO handle failure: %d\n", ret);
+ break;
+ }
+ acrn_ioreq_complete_request(client, vcpu, req);
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * For the non-default I/O clients, give them chance to complete the current
+ * I/O requests if there are any. For the default I/O client, it is safe to
+ * clear all pending I/O requests because the clearing request is from ACRN
+ * userspace.
+ */
+void acrn_ioreq_request_clear(struct acrn_vm *vm)
+{
+ struct acrn_ioreq_client *client;
+ bool has_pending = false;
+ unsigned long vcpu;
+ int retry = 10;
+
+ /*
+ * IO requests of this VM will be completed directly in
+ * acrn_ioreq_dispatch if ACRN_VM_FLAG_CLEARING_IOREQ flag is set.
+ */
+ set_bit(ACRN_VM_FLAG_CLEARING_IOREQ, &vm->flags);
+
+ /*
+ * acrn_ioreq_request_clear is only called in VM reset case. Simply
+ * wait 100ms in total for the IO requests' completion.
+ */
+ do {
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ list_for_each_entry(client, &vm->ioreq_clients, list) {
+ has_pending = has_pending_request(client);
+ if (has_pending)
+ break;
+ }
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+
+ if (has_pending)
+ schedule_timeout_interruptible(HZ / 100);
+ } while (has_pending && --retry > 0);
+ if (retry == 0)
+ dev_warn(acrn_dev.this_device,
+ "%s cannot flush pending request!\n", client->name);
+
+ /* Clear all ioreqs belonging to the default client */
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ client = vm->default_client;
+ if (client) {
+ vcpu = find_next_bit(client->ioreqs_map,
+ ACRN_IO_REQUEST_MAX, 0);
+ while (vcpu < ACRN_IO_REQUEST_MAX) {
+ acrn_ioreq_complete_request(client, vcpu, NULL);
+ vcpu = find_next_bit(client->ioreqs_map,
+ ACRN_IO_REQUEST_MAX, vcpu + 1);
+ }
+ }
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+
+ /* Clear ACRN_VM_FLAG_CLEARING_IOREQ flag after the clearing */
+ clear_bit(ACRN_VM_FLAG_CLEARING_IOREQ, &vm->flags);
+}
+
+int acrn_ioreq_client_wait(struct acrn_ioreq_client *client)
+{
+ if (client->is_default) {
+ /*
+ * In the default client, a user space thread waits on the
+ * waitqueue. The is_destroying() check is used to notify user
+ * space the client is going to be destroyed.
+ */
+ wait_event_interruptible(client->wq,
+ has_pending_request(client) ||
+ is_destroying(client));
+ if (is_destroying(client))
+ return -ENODEV;
+ } else {
+ wait_event_interruptible(client->wq,
+ has_pending_request(client) ||
+ kthread_should_stop());
+ }
+
+ return 0;
+}
+
+static bool in_range(struct acrn_ioreq_range *range,
+ struct acrn_io_request *req)
+{
+ bool ret = false;
+
+ if (range->type == req->type) {
+ switch (req->type) {
+ case ACRN_IOREQ_TYPE_MMIO:
+ if (req->reqs.mmio_request.address >= range->start &&
+ (req->reqs.mmio_request.address +
+ req->reqs.mmio_request.size - 1) <= range->end)
+ ret = true;
+ break;
+ case ACRN_IOREQ_TYPE_PORTIO:
+ if (req->reqs.pio_request.address >= range->start &&
+ (req->reqs.pio_request.address +
+ req->reqs.pio_request.size - 1) <= range->end)
+ ret = true;
+ break;
+ default:
+ break;
+ }
+ }
+
+ return ret;
+}
+
+static struct acrn_ioreq_client *find_ioreq_client(struct acrn_vm *vm,
+ struct acrn_io_request *req)
+{
+ struct acrn_ioreq_client *client, *found = NULL;
+ struct acrn_ioreq_range *range;
+
+ lockdep_assert_held(&vm->ioreq_clients_lock);
+
+ list_for_each_entry(client, &vm->ioreq_clients, list) {
+ read_lock_bh(&client->range_lock);
+ list_for_each_entry(range, &client->range_list, list) {
+ if (in_range(range, req)) {
+ found = client;
+ break;
+ }
+ }
+ read_unlock_bh(&client->range_lock);
+ if (found)
+ break;
+ }
+ return found ? found : vm->default_client;
+}
+
+/**
+ * acrn_ioreq_client_create() - Create an ioreq client
+ * @vm: The VM that this client belongs to
+ * @handler: The ioreq_handler of ioreq client acrn_hsm will create a kernel
+ * thread and call the handler to handle I/O requests.
+ * @priv: Private data for the handler
+ * @is_default: If it is the default client
+ * @name: The name of ioreq client
+ *
+ * Return: acrn_ioreq_client pointer on success, NULL on error
+ */
+struct acrn_ioreq_client *acrn_ioreq_client_create(struct acrn_vm *vm,
+ ioreq_handler_t handler,
+ void *priv, bool is_default,
+ const char *name)
+{
+ struct acrn_ioreq_client *client;
+
+ if (!handler && !is_default) {
+ dev_dbg(acrn_dev.this_device,
+ "Cannot create non-default client w/o handler!\n");
+ return NULL;
+ }
+ client = kzalloc(sizeof(*client), GFP_KERNEL);
+ if (!client)
+ return NULL;
+
+ client->handler = handler;
+ client->vm = vm;
+ client->priv = priv;
+ client->is_default = is_default;
+ if (name)
+ strncpy(client->name, name, sizeof(client->name) - 1);
+ rwlock_init(&client->range_lock);
+ INIT_LIST_HEAD(&client->range_list);
+ init_waitqueue_head(&client->wq);
+
+ if (client->handler) {
+ client->thread = kthread_run(ioreq_task, client, "VM%u-%s",
+ client->vm->vmid, client->name);
+ if (IS_ERR(client->thread)) {
+ kfree(client);
+ return NULL;
+ }
+ }
+
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ if (is_default)
+ vm->default_client = client;
+ else
+ list_add(&client->list, &vm->ioreq_clients);
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+
+ dev_dbg(acrn_dev.this_device, "Created ioreq client %s.\n", name);
+ return client;
+}
+
+/**
+ * acrn_ioreq_client_destroy() - Destroy an ioreq client
+ * @client: The ioreq client
+ */
+void acrn_ioreq_client_destroy(struct acrn_ioreq_client *client)
+{
+ struct acrn_ioreq_range *range, *next;
+ struct acrn_vm *vm = client->vm;
+
+ dev_dbg(acrn_dev.this_device,
+ "Destroy ioreq client %s.\n", client->name);
+ ioreq_pause();
+ set_bit(ACRN_IOREQ_CLIENT_DESTROYING, &client->flags);
+ if (client->is_default)
+ wake_up_interruptible(&client->wq);
+ else
+ kthread_stop(client->thread);
+
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ if (client->is_default)
+ vm->default_client = NULL;
+ else
+ list_del(&client->list);
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+
+ write_lock_bh(&client->range_lock);
+ list_for_each_entry_safe(range, next, &client->range_list, list) {
+ list_del(&range->list);
+ kfree(range);
+ }
+ write_unlock_bh(&client->range_lock);
+ kfree(client);
+
+ ioreq_resume();
+}
+
+static int acrn_ioreq_dispatch(struct acrn_vm *vm)
+{
+ struct acrn_ioreq_client *client;
+ struct acrn_io_request *req;
+ int i;
+
+ for (i = 0; i < vm->vcpu_num; i++) {
+ req = vm->ioreq_buf->req_slot + i;
+
+ /* barrier the read of processed of acrn_io_request */
+ if (smp_load_acquire(&req->processed) ==
+ ACRN_IOREQ_STATE_PENDING) {
+ /* Complete the IO request directly in clearing stage */
+ if (test_bit(ACRN_VM_FLAG_CLEARING_IOREQ, &vm->flags)) {
+ ioreq_complete_request(vm, i, req);
+ continue;
+ }
+
+ spin_lock_bh(&vm->ioreq_clients_lock);
+ client = find_ioreq_client(vm, req);
+ if (!client) {
+ dev_err(acrn_dev.this_device,
+ "Failed to find ioreq client!\n");
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+ return -EINVAL;
+ }
+ if (!client->is_default)
+ req->kernel_handled = 1;
+ else
+ req->kernel_handled = 0;
+ /*
+ * Add barrier() to make sure the writes are done
+ * before setting ACRN_IOREQ_STATE_PROCESSING
+ */
+ smp_store_release(&req->processed,
+ ACRN_IOREQ_STATE_PROCESSING);
+ set_bit(i, client->ioreqs_map);
+ wake_up_interruptible(&client->wq);
+ spin_unlock_bh(&vm->ioreq_clients_lock);
+ }
+ }
+
+ return 0;
+}
+
+static void ioreq_tasklet_handler(unsigned long data)
+{
+ struct acrn_vm *vm;
+
+ read_lock(&acrn_vm_list_lock);
+ list_for_each_entry(vm, &acrn_vm_list, list) {
+ if (!vm->ioreq_buf)
+ break;
+ acrn_ioreq_dispatch(vm);
+ }
+ read_unlock(&acrn_vm_list_lock);
+}
+
+static void ioreq_pause(void)
+{
+ /* Flush and disable the tasklet to ensure no I/O requests pending */
+ tasklet_disable(&ioreq_tasklet);
+}
+
+static void ioreq_resume(void)
+{
+ /* Schedule once after enabling in case other clients miss a tasklet */
+ tasklet_enable(&ioreq_tasklet);
+ tasklet_schedule(&ioreq_tasklet);
+}
+
+static void ioreq_intr_handler(void)
+{
+ tasklet_schedule(&ioreq_tasklet);
+}
+
+void acrn_ioreq_intr_setup(void)
+{
+ acrn_setup_intr_handler(ioreq_intr_handler);
+ tasklet_init(&ioreq_tasklet, ioreq_tasklet_handler, 0);
+}
+
+void acrn_ioreq_intr_remove(void)
+{
+ acrn_remove_intr_handler();
+}
+
+int acrn_ioreq_init(struct acrn_vm *vm, u64 buf_vma)
+{
+ struct acrn_ioreq_buffer *set_buffer;
+ struct page *page;
+ int ret;
+
+ if (vm->ioreq_buf)
+ return -EEXIST;
+
+ set_buffer = kzalloc(sizeof(*set_buffer), GFP_KERNEL);
+ if (!set_buffer)
+ return -ENOMEM;
+
+ ret = pin_user_pages_fast(buf_vma, 1,
+ FOLL_WRITE | FOLL_LONGTERM, &page);
+ if (unlikely(ret != 1) || !page) {
+ dev_err(acrn_dev.this_device, "Failed to pin ioreq page!\n");
+ ret = -EFAULT;
+ goto free_buf;
+ }
+
+ vm->ioreq_buf = page_address(page);
+ vm->ioreq_page = page;
+ set_buffer->ioreq_buf = page_to_phys(page);
+ ret = hcall_set_ioreq_buffer(vm->vmid, virt_to_phys(set_buffer));
+ if (ret < 0) {
+ dev_err(acrn_dev.this_device, "Failed to init ioreq buffer!\n");
+ unpin_user_page(page);
+ vm->ioreq_buf = NULL;
+ goto free_buf;
+ }
+
+ dev_dbg(acrn_dev.this_device,
+ "Init ioreq buffer %pK!\n", vm->ioreq_buf);
+ ret = 0;
+free_buf:
+ kfree(set_buffer);
+ return ret;
+}
+
+void acrn_ioreq_deinit(struct acrn_vm *vm)
+{
+ struct acrn_ioreq_client *client, *next;
+
+ dev_dbg(acrn_dev.this_device,
+ "Deinit ioreq buffer %pK!\n", vm->ioreq_buf);
+ /* Destroy all clients belonging to this VM */
+ list_for_each_entry_safe(client, next, &vm->ioreq_clients, list)
+ acrn_ioreq_client_destroy(client);
+ if (vm->default_client)
+ acrn_ioreq_client_destroy(vm->default_client);
+
+ if (vm->ioreq_buf && vm->ioreq_page) {
+ unpin_user_page(vm->ioreq_page);
+ vm->ioreq_buf = NULL;
+ }
+}
diff --git a/drivers/virt/acrn/vm.c b/drivers/virt/acrn/vm.c
index ff5df7acb551..4ee1a99df4b7 100644
--- a/drivers/virt/acrn/vm.c
+++ b/drivers/virt/acrn/vm.c
@@ -15,9 +15,12 @@
#include "acrn_drv.h"

/* List of VMs */
-static LIST_HEAD(acrn_vm_list);
-/* To protect acrn_vm_list */
-static DEFINE_MUTEX(acrn_vm_list_lock);
+LIST_HEAD(acrn_vm_list);
+/*
+ * acrn_vm_list is read in a tasklet which dispatch I/O requests and is wrote
+ * in VM creation ioctl. Use the rwlock mechanism to protect it.
+ */
+DEFINE_RWLOCK(acrn_vm_list_lock);

struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
struct acrn_vm_creation *vm_param)
@@ -32,12 +35,20 @@ struct acrn_vm *acrn_vm_create(struct acrn_vm *vm,
}

mutex_init(&vm->regions_mapping_lock);
+ INIT_LIST_HEAD(&vm->ioreq_clients);
+ spin_lock_init(&vm->ioreq_clients_lock);
vm->vmid = vm_param->vmid;
vm->vcpu_num = vm_param->vcpu_num;

- mutex_lock(&acrn_vm_list_lock);
+ if (acrn_ioreq_init(vm, vm_param->ioreq_buf) < 0) {
+ hcall_destroy_vm(vm_param->vmid);
+ vm->vmid = ACRN_INVALID_VMID;
+ return NULL;
+ }
+
+ write_lock_bh(&acrn_vm_list_lock);
list_add(&vm->list, &acrn_vm_list);
- mutex_unlock(&acrn_vm_list_lock);
+ write_unlock_bh(&acrn_vm_list_lock);

dev_dbg(acrn_dev.this_device, "VM %u created.\n", vm->vmid);
return vm;
@@ -52,9 +63,11 @@ int acrn_vm_destroy(struct acrn_vm *vm)
return 0;

/* Remove from global VM list */
- mutex_lock(&acrn_vm_list_lock);
+ write_lock_bh(&acrn_vm_list_lock);
list_del_init(&vm->list);
- mutex_unlock(&acrn_vm_list_lock);
+ write_unlock_bh(&acrn_vm_list_lock);
+
+ acrn_ioreq_deinit(vm);

ret = hcall_destroy_vm(vm->vmid);
if (ret < 0) {
diff --git a/include/uapi/linux/acrn.h b/include/uapi/linux/acrn.h
index c260d0e9caea..96ebc879b8d0 100644
--- a/include/uapi/linux/acrn.h
+++ b/include/uapi/linux/acrn.h
@@ -12,6 +12,129 @@
#include <linux/types.h>
#include <linux/uuid.h>

+#define ACRN_IO_REQUEST_MAX 16
+
+#define ACRN_IOREQ_STATE_PENDING 0
+#define ACRN_IOREQ_STATE_COMPLETE 1
+#define ACRN_IOREQ_STATE_PROCESSING 2
+#define ACRN_IOREQ_STATE_FREE 3
+
+#define ACRN_IOREQ_TYPE_PORTIO 0
+#define ACRN_IOREQ_TYPE_MMIO 1
+
+#define ACRN_IOREQ_DIR_READ 0
+#define ACRN_IOREQ_DIR_WRITE 1
+
+struct acrn_mmio_request {
+ __u32 direction;
+ __u32 reserved;
+ __u64 address;
+ __u64 size;
+ __u64 value;
+};
+
+struct acrn_pio_request {
+ __u32 direction;
+ __u32 reserved;
+ __u64 address;
+ __u64 size;
+ __u32 value;
+};
+
+/**
+ * struct acrn_io_request - 256-byte ACRN I/O request
+ * @type: Type of this request (ACRN_IOREQ_TYPE_*).
+ * @completion_polling: Polling flag. Hypervisor will poll completion of the
+ * I/O request if this flag set.
+ * @reserved0: Reserved fields.
+ * @reqs: Union of different types of request. Byte offset: 64.
+ * @reqs.pio_request: PIO request data of the I/O request.
+ * @reqs.mmio_request: MMIO request data of the I/O request.
+ * @reqs.data: Raw data of the I/O request.
+ * @reserved1: Reserved fields.
+ * @kernel_handled: Flag indicates this request need be handled in kernel.
+ * @processed: The status of this request (ACRN_IOREQ_STATE_*).
+ *
+ * The state transitions of ACRN I/O request:
+ *
+ * FREE -> PENDING -> PROCESSING -> COMPLETE -> FREE -> ...
+ *
+ * An I/O request in COMPLETE or FREE state is owned by the hypervisor. HSM and
+ * ACRN userspace are in charge of processing the others.
+ *
+ * On basis of the states illustrated above, a typical lifecycle of ACRN IO
+ * request would look like:
+ *
+ * Flow (assume the initial state is FREE)
+ * |
+ * | Service VM vCPU 0 Service VM vCPU x User vCPU y
+ * |
+ * | hypervisor:
+ * | fills in type, addr, etc.
+ * | pauses the User VM vCPU y
+ * | sets the state to PENDING (a)
+ * | fires an upcall to Service VM
+ * |
+ * | HSM:
+ * | scans for PENDING requests
+ * | sets the states to PROCESSING (b)
+ * | assigns the requests to clients (c)
+ * V
+ * | client:
+ * | scans for the assigned requests
+ * | handles the requests (d)
+ * | HSM:
+ * | sets states to COMPLETE
+ * | notifies the hypervisor
+ * |
+ * | hypervisor:
+ * | resumes User VM vCPU y (e)
+ * |
+ * | hypervisor:
+ * | post handling (f)
+ * V sets states to FREE
+ *
+ * Note that the procedures (a) to (f) in the illustration above require to be
+ * strictly processed in the order. One vCPU cannot trigger another request of
+ * I/O emulation before completing the previous one.
+ *
+ * Atomic and barriers are required when HSM and hypervisor accessing the state
+ * of &struct acrn_io_request.
+ *
+ */
+struct acrn_io_request {
+ __u32 type;
+ __u32 completion_polling;
+ __u32 reserved0[14];
+ union {
+ struct acrn_pio_request pio_request;
+ struct acrn_mmio_request mmio_request;
+ __u64 data[8];
+ } reqs;
+ __u32 reserved1;
+ __u32 kernel_handled;
+ __u32 processed;
+} __attribute__((aligned(256)));
+
+struct acrn_io_request_buffer {
+ union {
+ struct acrn_io_request req_slot[ACRN_IO_REQUEST_MAX];
+ __u8 reserved[4096];
+ };
+};
+
+/**
+ * struct acrn_ioreq_notify - The structure of ioreq completion notification
+ * @vmid: User VM ID
+ * @reserved: Reserved
+ * @vcpu: vCPU ID
+ */
+struct acrn_ioreq_notify {
+ __u16 vmid;
+ __u16 reserved;
+ __u32 vcpu;
+};
+
/**
* struct acrn_vm_creation - Info to create a User VM
* @vmid: User VM ID returned from the hypervisor
@@ -165,6 +288,17 @@ struct acrn_vm_memmap {
#define ACRN_IOCTL_SET_VCPU_REGS \
_IOW(ACRN_IOCTL_TYPE, 0x16, struct acrn_vcpu_regs)

+#define ACRN_IOCTL_NOTIFY_REQUEST_FINISH \
+ _IOW(ACRN_IOCTL_TYPE, 0x31, struct acrn_ioreq_notify)
+#define ACRN_IOCTL_CREATE_IOREQ_CLIENT \
+ _IO(ACRN_IOCTL_TYPE, 0x32)
+#define ACRN_IOCTL_ATTACH_IOREQ_CLIENT \
+ _IO(ACRN_IOCTL_TYPE, 0x33)
+#define ACRN_IOCTL_DESTROY_IOREQ_CLIENT \
+ _IO(ACRN_IOCTL_TYPE, 0x34)
+#define ACRN_IOCTL_CLEAR_VM_IOREQ \
+ _IO(ACRN_IOCTL_TYPE, 0x35)
+
#define ACRN_IOCTL_SET_MEMSEG \
_IOW(ACRN_IOCTL_TYPE, 0x41, struct acrn_vm_memmap)
#define ACRN_IOCTL_UNSET_MEMSEG \
--
2.28.0