[kvm-unit-tests PATCH v3 00/17] x86_64 UEFI and AMD SEV/SEV-ES support

[Zixuan Wang <zxwang42@gmail.com>]

Hello,

This patch series updates the x86_64 KVM-Unit-Tests to run under UEFI
and culminates in enabling AMD SEV/SEV-ES. The patches are organized as
four parts.

The first part (patch 1) refactors the current Multiboot start-up code
by converting assembly data structures into C. This enables the
follow-up UEFI patches to reuse these data structures without redefining
or duplicating them in assembly.

The second part (patches 2-3) copies code from Varad's patch set [1]
that builds EFI stubs without depending on GNU-EFI. Part 3 and 4 are
built on top of this part.

The third part (patches 4-11) enables the x86_64 test cases to run
under UEFI. In particular, these patches allow the x86_64 test cases to
be built as EFI executables and take full control of the guest VM. The
efi_main() function sets up the KVM-Unit-Tests framework to run under
UEFI and then launches the test cases' main() functions. To date, we
have 38/43 test cases running with UEFI using this approach.

The fourth part of the series (patches 12-17) focuses on SEV. In
particular, these patches introduce SEV/SEV-ES set up code into the EFI
set up process, including checking if SEV is supported, setting c-bits
for page table entries, and (notably) reusing the UEFI #VC handler so
that the set up process does not need to re-implement it (a test case
can always implement a new #VC handler and load it after set up is
finished). Using this approach, we are able to launch the x86_64 test
cases under SEV-ES and exercise KVM's VMGEXIT handler.

Note, a previous feedback [3] indicated that long-term we'd like to
instrument KVM-Unit-Tests with it's own #VC handler. However, we still
believe that the current approach is good as an intermediate solution,
because it unlocks a lot of testing and we do not expect that testing
to be inherently tied to the UEFI's #VC handler. Rather, test cases
should be tied to the underlying GHCB spec implemented by an
arbitrary #VC handler.

See the Part 1 to Part 4 summaries, below, for a high-level breakdown
of how the patches are organized.

Part 1 Summary:
Commit 1 refactors boot-related data structures from assembly to C.

Part 2 Summary:
Commits 2-3 copy code from Varad's patch set [1] that implements
EFI-related helper functions to replace the GNU-EFI library.

Part 3 Summary:
Commits 4-5 introduce support to build test cases with EFI support.

Commits 6-10 set up KVM-Unit-Tests to run under UEFI. In doing so, these
patches incrementally enable most existing x86_64 test cases to run
under UEFI.

Commit 11 fixes several test cases that fail to compile with EFI due
to UEFI's position independent code (PIC) requirement.

Part 4 Summary:
Commits 12-13 introduce support for SEV by adding code to set the SEV
c-bit in page table entries.

Commits 14-16 introduce support for SEV-ES by reusing the UEFI #VC
handler in KVM-Unit-Tests. They also fix GDT and IDT issues that occur
when reusing UEFI functions in KVM-Unit-Tests.

Commit 17 adds additional test cases for SEV-ES.

Changes V2 -> V3:
V3 Patch #  Changes
----------  -------
     01/17  (New patch) refactors assembly data structures in C
     02/17  Adds a missing alignment attribute
            Renames the file uefi.h to efi.h
     03/17  Adds an SPDX header, fixes a comment style issue
     06/17  Removes assembly data structure definitions
     07/17  Removes assembly data structure definitions
     12/17  Simplifies an if condition code
     14/17  Simplifies an if condition code
     15/17  Removes GDT copying for SEV-ES #VC handler

Notes on page table set up code:
Paolo suggested unifying  the page table definitions in cstart64.S and
UEFI start-up code [5]. We tried but found it hard to implement due to
the real/long mode issue: a page table set up function written in C is
by default compiled to run in long mode. However, cstart64.S requires
page table setup before entering long mode. Calling a long mode function
from real/protected mode crashes the guest VM. Thus we chose not to
implement this feature in this patch set. More details can be found in
our off-list GitHub review [6].

Changes V1 -> V2:
1. Merge Varad's patches [1] as the foundation of our V2 patch set [4].
2. Remove AMD SEV/SEV-ES config flags and macros (patches 11-17)
3. Drop one commit 'x86 UEFI: Move setjmp.h out of desc.h' because we do
not link GNU-EFI library.

Notes on authorships and attributions:
The first two commits are from Varad's patch set [1], so they are
tagged as 'From:' and 'Signed-off-by:' Varad. Commits 3-7 are from our
V1 patch set [2], and since Varad implemented similar code [1], these
commits are tagged as 'Co-developed-by:' and 'Signed-off-by:' Varad.

Notes on patch sets merging strategy:
We understand that the current merging strategy (reorganizing and
squeezing Varad's patches into two) reduces Varad's authorships, and we
hope the additional attribution tags make up for it. We see another
approach which is to build our patch set on top of Varad's original
patch set, but this creates some noise in the final patch set, e.g.,
x86/cstart64.S is modified in Varad's part and later reverted in our
part as we implement start up code in C. For the sake of the clarity of
the code history, we believe the current approach is the best effort so
far, and we are open to all kinds of opinions.

[1] https://lore.kernel.org/kvm/20210819113400.26516-1-varad.gautam@suse.com/
[2] https://lore.kernel.org/kvm/20210818000905.1111226-1-zixuanwang@google.com/
[3] https://lore.kernel.org/kvm/YSA%2FsYhGgMU72tn+@google.com/
[4] https://lore.kernel.org/kvm/20210827031222.2778522-1-zixuanwang@google.com/
[5] https://lore.kernel.org/kvm/3fd467ae-63c9-adba-9d29-09b8a7beb92d@redhat.com/
[6] https://github.com/marc-orr/KVM-Unit-Tests-dev-fork/pull/1

Regards,
Zixuan Wang

Varad Gautam (2):
  x86 UEFI: Copy code from Linux
  x86 UEFI: Implement UEFI function calls

Zixuan Wang (15):
  x86: Move IDT, GDT and TSS to desc.c
  x86 UEFI: Copy code from GNU-EFI
  x86 UEFI: Boot from UEFI
  x86 UEFI: Load IDT after UEFI boot up
  x86 UEFI: Load GDT and TSS after UEFI boot up
  x86 UEFI: Set up memory allocator
  x86 UEFI: Set up RSDP after UEFI boot up
  x86 UEFI: Set up page tables
  x86 UEFI: Convert x86 test cases to PIC
  x86 AMD SEV: Initial support
  x86 AMD SEV: Page table with c-bit
  x86 AMD SEV-ES: Check SEV-ES status
  x86 AMD SEV-ES: Copy UEFI #VC IDT entry
  x86 AMD SEV-ES: Set up GHCB page
  x86 AMD SEV-ES: Add test cases

 .gitignore                 |   3 +
 Makefile                   |  29 +-
 README.md                  |   6 +
 configure                  |   6 +
 lib/efi.c                  | 118 ++++++++
 lib/efi.h                  |  22 ++
 lib/linux/efi.h            | 539 +++++++++++++++++++++++++++++++++++++
 lib/x86/acpi.c             |  38 ++-
 lib/x86/acpi.h             |  11 +
 lib/x86/amd_sev.c          | 174 ++++++++++++
 lib/x86/amd_sev.h          |  63 +++++
 lib/x86/asm/page.h         |  28 +-
 lib/x86/asm/setup.h        |  35 +++
 lib/x86/desc.c             |  46 +++-
 lib/x86/desc.h             |   6 +-
 lib/x86/setup.c            | 246 +++++++++++++++++
 lib/x86/usermode.c         |   3 +-
 lib/x86/vm.c               |  18 +-
 x86/Makefile.common        |  68 +++--
 x86/Makefile.i386          |   5 +-
 x86/Makefile.x86_64        |  58 ++--
 x86/access.c               |   9 +-
 x86/amd_sev.c              |  94 +++++++
 x86/cet.c                  |   8 +-
 x86/cstart64.S             |  77 +-----
 x86/efi/README.md          |  63 +++++
 x86/efi/crt0-efi-x86_64.S  |  79 ++++++
 x86/efi/efistart64.S       |  77 ++++++
 x86/efi/elf_x86_64_efi.lds |  81 ++++++
 x86/efi/reloc_x86_64.c     |  96 +++++++
 x86/efi/run                |  63 +++++
 x86/emulator.c             |   5 +-
 x86/eventinj.c             |   6 +-
 x86/run                    |  16 +-
 x86/smap.c                 |   8 +-
 x86/umip.c                 |  10 +-
 x86/vmx.c                  |   8 +-
 37 files changed, 2067 insertions(+), 155 deletions(-)
 create mode 100644 lib/efi.c
 create mode 100644 lib/efi.h
 create mode 100644 lib/linux/efi.h
 create mode 100644 lib/x86/amd_sev.c
 create mode 100644 lib/x86/amd_sev.h
 create mode 100644 lib/x86/asm/setup.h
 create mode 100644 x86/amd_sev.c
 create mode 100644 x86/efi/README.md
 create mode 100644 x86/efi/crt0-efi-x86_64.S
 create mode 100644 x86/efi/efistart64.S
 create mode 100644 x86/efi/elf_x86_64_efi.lds
 create mode 100644 x86/efi/reloc_x86_64.c
 create mode 100755 x86/efi/run

-- 
2.33.0