This patch series introduces vhost-user-spi device support to QEMU and synchronizes relevant standard headers from upstream Linux.
The series consists of the following changes: 1. Synchronize virtio_spi.h from Linux kernel (v6.18-rc3) using scripts/update-linux-headers.sh. 2. Implement vhost-user-spi and vhost-user-spi-pci devices in QEMU, enabling virtio-based SPI communication via the vhost-user protocol. The new device implementation follows the virtio-spi specification and leverages the upstream Linux virtio-spi driver. This enables QEMU to emulate SPI devices using the vhost-user protocol, facilitating integration with external SPI daemons and improving virtualization support for SPI peripherals. Changes between V3 and V2: - Removed the patch to update virtio_ids.h since it is already updated Changes between V2 and V1: - Added vhost-user-spi entry in docs/system/devices/virtio/vhost-user.rst
