virt: acrn: Introduce ioeventfd

ioeventfd is a mechanism to register PIO/MMIO regions to trigger an
eventfd signal when written to by a User VM. ACRN userspace can register
any arbitrary I/O address with a corresponding eventfd and then pass the
eventfd to a specific end-point of interest for handling.

Vhost is a kernel-level virtio server which uses eventfd for signalling.
To support vhost on ACRN, ioeventfd is introduced in HSM.

A new I/O client dedicated to ioeventfd is associated with a User VM
during VM creation. HSM provides ioctls to associate an I/O region with
a eventfd. The I/O client signals a eventfd once its corresponding I/O
region is matched with an I/O request.

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>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-16-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/virt/acrn/hsm.c b/drivers/virt/acrn/hsm.c
index b7f2deddc3e7..0b4e88b0b6bc 100644
--- a/drivers/virt/acrn/hsm.c
+++ b/drivers/virt/acrn/hsm.c
@@ -111,6 +111,7 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
 	struct acrn_vcpu_regs *cpu_regs;
 	struct acrn_ioreq_notify notify;
 	struct acrn_ptdev_irq *irq_info;
+	struct acrn_ioeventfd ioeventfd;
 	struct acrn_vm_memmap memmap;
 	struct acrn_msi_entry *msi;
 	struct acrn_pcidev *pcidev;
@@ -336,6 +337,16 @@ static long acrn_dev_ioctl(struct file *filp, unsigned int cmd,
 
 		ret = pmcmd_ioctl(cstate_cmd, (void __user *)ioctl_param);
 		break;
+	case ACRN_IOCTL_IOEVENTFD:
+		if (copy_from_user(&ioeventfd, (void __user *)ioctl_param,
+				   sizeof(ioeventfd)))
+			return -EFAULT;
+
+		if (ioeventfd.reserved != 0)
+			return -EINVAL;
+
+		ret = acrn_ioeventfd_config(vm, &ioeventfd);
+		break;
 	default:
 		dev_dbg(acrn_dev.this_device, "Unknown IOCTL 0x%x!\n", cmd);
 		ret = -ENOTTY;