openhcl_boot: dynamic page table construction for TDX #2286
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This PR modifies files containing For more on why we check whole files, instead of just diffs, check out the Rustonomicon |
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Pulling this out of draft mode so we can see CI results - we should not merge this until after Chris has reviewed and merged #2062 |
| unsafe { | ||
| core::ptr::copy_nonoverlapping( | ||
| page_tables.as_ptr(), | ||
| page_table_region.range.start() as *mut u8, |
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I'm not sure it's guaranteed that page_table_region is valid to be accessed. In most cases, we are probably allocating from memory that is in the initial identity mapped region, but it's possible that the address space manager could choose to give you some other block of memory where we don't have a valid identity mapping for.
I think this leaves you with two options:
a) prereserve a region at load time that we may shrink to fit to return memory to the kernel (or just waste 20 pages and put a TODO there)
b) use the local_map to map this region on-the-fly, and then you don't need to use unsafe.
If possible, we could use b?
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I think also using the local_map gives you a &mut [u8] which you can also then save another copy and allocation of the flattened page table, and you can pass that to the builder itself, right?
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This PR builds on the the loader refactor in #2062 to dynamically construct R+X page tables for AP startup in the boot shim.
The context for these changes can be found in issue #1563