The modernization of PCIe hotplug in Linux

It has the concept of "lost" devices, which causes most API calls to return errors and the application is able to clean up and try again with a new graphics device. (Of course the application might choose to just crash instead). The spec says "The host address space corresponding to device memory mapped using vkMapMemory is still valid, and host memory accesses to these mapped regions are still valid, but the contents are undefined", which I guess means the kernel can't unmap the memory when it detects the GPU has gone away (because that would likely crash the application), but could map the whole range onto a single dummy page or something.