virt: acrn: Introduce I/O request management

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 worker to dispatch I/O requests.
d) The worker 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.

Cc: Davidlohr Bueso <dave@stgolabs.net>
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>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-10-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 41 insertions, 2 deletions

diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
index 2c40d3dc5e94..1cc0c612dc09 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 i, ret = 0;
 
@@ -147,6 +148,35 @@ 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;
+
+		if (notify.reserved != 0)
+			return -EINVAL;
+
+		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;
@@ -188,14 +218,23 @@ 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;
+	ret = acrn_ioreq_intr_setup();
+	if (ret) {
+		pr_err("Setup I/O request handler failed!\n");
+		misc_deregister(&acrn_dev);
+		return ret;
+	}
+	return 0;
 }
 
 static void __exit hsm_exit(void)
 {
+	acrn_ioreq_intr_remove();
 	misc_deregister(&acrn_dev);
 }
 module_init(hsm_init);