Fix TrenchBoot issues

[BeataZdunczyk]

Brief summary
Fix listed issues:

• Xen is booting very slowly after Dynamic Launch xen#16
• Cannot start any VM/qube with PCI device passed through to it after Dynamic Launch xen#18
• Test Latest GRUB, kernel, and SKL is not compatible #6 and close
• TrenchBoot as a main provider of Anti Evil Maid for QubesOS for all x86 platforms #4

In what form and where the task results must be shown

• PR to respective repositories
• Closed issue, or comment explaining why software fix isn't possible/feasible
• Link to openQA test runs that pass after the issues are resolved
• Update relevant GitHub issue(s)

[SergiiDmytruk]

TrenchBoot/xen#16

Closed TrenchBoot/xen#17 as those changes were already
integrated.

Testing on VP4670 that was used to report the issue is problematic. The unit which worked fine before is currently not available and the other one seems to have some hardware issues (weird delays, kernel crashes that don't let Linux boot).

Further performance improvements likely need moving MTTR restoration from e820.c:machine_specific_memory_setup() to setup.c:__start_xen() along with moving slaunch-related invocations earlier in that function (as early as possible), but this needs a working hardware to tests things.

TrenchBoot/xen#18

No suitable hardware to test this at the moment.

Test #6 and close

Closed: #6 (comment)

#4

Posted a short update in #4 (comment) and checked most of the boxes of the top post. Can either leave it open and use for further tracking or if want to close, make a new issue describing the current state and ongoing activities and close this issue then.