[RFC 2/2] drivers: vfio: pci: Add virtual MSI doorbell support.

In ARM/ARM64 MSI transactions goes through iommu/smmu. This means there has to be an iommu mapping created for MSI addresses. This patch adds a new ioctl "VFIO_DEVICE_PCI_MSI_VIRT_DOORBELL". Userspace can call this ioctl to do following things: 1. Create a virtual doorbell mapping between MSI

[RFC 2/2] drivers: vfio: pci: Add virtual MSI doorbell support.

In ARM/ARM64 MSI transactions goes through iommu/smmu. This means there has to be an iommu mapping created for MSI addresses. This patch adds a new ioctl VFIO_DEVICE_PCI_MSI_VIRT_DOORBELL. Userspace can call this ioctl to do following things: 1. Create a virtual doorbell mapping between MSI IOVA