openhcl_boot: Serial logging for SEV-SNP #1378

romank-msft · 2025-05-17T01:45:38Z

SEV-SNP has been the only platform where serial logging
isn't supported in the boot shim.

Implement the GHCB calls and use that for serial logging
via the IOIO exits.

Validated with the latest main, both the ship and debug builds.

vm/loader/src/paravisor.rs

vm/x86/x86defs/src/snp.rs

romank-msft · 2025-05-20T22:42:54Z

Don't approve just yet folks, will look more at the page acceptance code to make sure it matches the manuals.

openhcl/virt_mshv_vtl/src/processor/snp/mod.rs

openhcl/openhcl_boot/src/arch/x86_64/snp.rs

romank-msft · 2025-05-21T17:44:41Z

@jstarks Addressed your comments, appreciated very much! pvalidate makes the VM shut down when accepting the GHCB page back when unintializating. Looking what's up, followed the usual procedure, shuffled the steps around just in case. @chris-oo @mebersol @sluck-msft could you look to see what's suspicious?

openhcl/openhcl_boot/src/arch/x86_64/snp.rs

romank-msft · 2025-05-22T21:52:09Z

@jstarks Addressed your comments, appreciated very much! pvalidate makes the VM shut down when accepting the GHCB page back when unintializating. Looking what's up, followed the usual procedure, shuffled the steps around just in case. @chris-oo @mebersol @sluck-msft could you look to see what's suspicious?

found a way to rseolve

SEV-SNP has been the only platform where serial logging isn't supported in the boot shim. Implement the GHCB calls and use that for serial logging via the IOIO exits.

jstarks reviewed May 19, 2025

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jstarks reviewed May 19, 2025

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romank-msft marked this pull request as ready for review May 20, 2025 20:10

romank-msft requested review from a team as code owners May 20, 2025 20:10

mebersol added the backport_2505 label May 20, 2025