ac7c5b1761
VirtIO capability structures can start at non-page-aligned offsets within\nBARs. The kernel physmap requires page-aligned addresses. Align the physical\naddress down, adjust the size, and apply the page offset to the returned\npointer. Track the original map pointer/size separately for correct unmapping. Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent) Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>