mm: Add unit tests for kernel mapping, guestmem ops, address checks

[Zildj1an]

Add unit tests to evaluate offline correct behavior of memory components: kernel mappings (address_space.rs), read and write operations (guestmem.rs) and valid physical address checking (memory.rs).

[00xc]

At least one test is failing inside the SVSM, so we need that fixed at the minimum. I would also really want the Miri addition to go in, as I'm running Miri tests nightly.

[Zildj1an]

At least one test is failing inside the SVSM, so we need that fixed at the minimum. I would also really want the Miri addition to go in, as I'm running Miri tests nightly.

I foresee the complexity of these and future tests growing considerably if we want all to be able to run inside the SVSM. My intention when I wrote and added these tests was to run them offline. For example, I need to either implement new functions that use KERNEL_MAPPING_TEST instead, or I have to consider the ramifications of using KERNEL_MAPPING uninitialized, etc. So I'm wondering, Is there a way we can leave some tests for offline testing only?

[00xc]

I foresee the complexity of these and future tests growing considerably if we want all to be able to run inside the SVSM. My intention when I wrote and added these tests was to run them offline. For example, I need to either implement new functions that use KERNEL_MAPPING_TEST instead, or I have to consider the ramifications of using KERNEL_MAPPING uninitialized, etc. So I'm wondering, Is there a way we can leave some tests for offline testing only?

Yes, there are already some tests that are ignored inside the SVSM, for example in mm/alloc.rs. You can do that with:

#[test]
#[cfg_attr(test_in_svsm, ignore = "<REASON>")]
fn my_test() {}

I think you can also omit the reason.

[Zildj1an]

I foresee the complexity of these and future tests growing considerably if we want all to be able to run inside the SVSM. My intention when I wrote and added these tests was to run them offline. For example, I need to either implement new functions that use KERNEL_MAPPING_TEST instead, or I have to consider the ramifications of using KERNEL_MAPPING uninitialized, etc. So I'm wondering, Is there a way we can leave some tests for offline testing only?

Yes, there are already some tests that are ignored inside the SVSM, for example in mm/alloc.rs. You can do that with:

#[test]
#[cfg_attr(test_in_svsm, ignore = "<REASON>")]
fn my_test() {}

I think you can also omit the reason.

Thanks, I'm doing this, opening new clean PR