commit b470f93e01a5b16499ebd7be6f9371ee8bddf2c0
author Joshua Seaton <joshuaseaton@google.com> Fri Mar 28 10:18:38 2025 -0700
committer CQ Bot <fuchsia-internal-scoped@luci-project-accounts.iam.gserviceaccount.com> Fri Mar 28 10:18:38 2025 -0700
tree 95c714f701659fc70bc64fb5e9bcce10a2af38ae
parent f30daf4fa73090906f593dd8cdab77365b8a4a87

[kernel][phys][vm] Formalize VM hand-off

This change introduces phys handoff abstractions describing the mappings
it created along with the VMARs - subVMARs of the root - that these
should end up in, as well as updating the kernel's VM initialization to
simply iterate over these and follow through with VMAR creation and
mapping reservation in a table-driven fashion. The table-driven aspect
simplifies things, is more flexible (being in turn driven by the source
of truth for those mappings), and readily extends support to the other
mappings we intend to make in physmap (e.g., periphmap and stacks).

This replaces the previous VMAR creation + reservation logic in VM init
that explicitly did this for the kernel and physmap alone.

Example VM init logging as of this change:
```
[00000.000] 00000:01025> initializing vm
[00000.000] 00000:01025> VM: handing off VMAR from phys: physmap @ [0xffffff8000000000, 0xffffff9000000000)
[00000.000] 00000:01025> VM: * mapping: physmap (rw): [0, 0x1000000000) -> [0xffffff8000000000, 0xffffff9000000000)
[00000.000] 00000:01025> VM: handing off VMAR from phys: kernel @ [0xffffffff00000000, 0xffffffff004af000)
[00000.000] 00000:01025> VM: * mapping: segment (p_vaddr = 0x0) (r): [0x3229000, 0x32a2000) -> [0xffffffff00000000, 0xffffffff00079000)
[00000.000] 00000:01025> VM: * mapping: segment (p_vaddr = 0x79000) (rx): [0x32a2000, 0x361b000) -> [0xffffffff00079000, 0xffffffff003f2000)
[00000.000] 00000:01025> VM: * mapping: segment (p_vaddr = 0x3f2000) (r): [0x361b000, 0x3626000) -> [0xffffffff003f2000, 0xffffffff003fd000)
[00000.000] 00000:01025> VM: * mapping: segment (p_vaddr = 0x3fd000) (rw): [0x3626000, 0x36d8000) -> [0xffffffff003fd000, 0xffffffff004af000)
```

Bug: 42164859
Change-Id: I0edb93e777ca945bc437b666b37cbfc49bfcd1ca
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/1178312
Reviewed-by: Roland McGrath <mcgrathr@google.com>
Fuchsia-Auto-Submit: Joshua Seaton <joshuaseaton@google.com>
Reviewed-by: Adrian Danis <adanis@google.com>
Commit-Queue: Joshua Seaton <joshuaseaton@google.com>