audk/OvmfPkg/Microvm
Min Xu 2b80269d98 OvmfPkg: Update Sec to support Tdx
RFC: https://bugzilla.tianocore.org/show_bug.cgi?id=3429

There are below major changes in this commit.

1. SecEntry.nasm
In TDX BSP and APs goes to the same entry point in SecEntry.nasm.

BSP initialize the temporary stack and then jumps to SecMain, just as
legacy Ovmf does.

APs spin in a modified mailbox loop using initial mailbox structure.
Its structure defition is in OvmfPkg/Include/IndustryStandard/IntelTdx.h.
APs wait for command to see if the command is for me. If so execute the
command.

2. Sec/SecMain.c
When host VMM create the Td guest, the system memory informations are
stored in TdHob, which is a memory region described in Tdx metadata.
The system memory region in TdHob should be accepted before it can be
accessed. So the major task of this patch is to process the TdHobList
to accept the memory. After that TDVF follow the standard OVMF flow
and jump to PEI phase.

PcdUse1GPageTable is set to FALSE by default in OvmfPkgX64.dsc. It gives
no chance for Intel TDX to support 1G page table. To support 1G page
table this PCD is set to TRUE in OvmfPkgX64.dsc.

TDX_GUEST_SUPPORTED is defined in OvmfPkgX64.dsc. This macro wraps the
Tdx specific code.

TDX only works on X64, so the code is only valid in X64 arch.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
2022-04-02 08:15:12 +00:00
..
MicrovmX64.dsc OvmfPkg: Update Sec to support Tdx 2022-04-02 08:15:12 +00:00
MicrovmX64.fdf OvmfPkg/Microvm/virtio: add virtio-mmio support 2021-12-13 12:16:32 +00:00
README OvmfPkg/Microvm: add README 2021-12-13 12:16:32 +00:00

README

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This is an *experimental* port of OVMF for the QEMU microvm
machine type.

microvm background info
-----------------------

microvm is designed for modern, virtio-based workloads.  Most legacy
lpc/isa devices like pit and pic can be turned off.  virtio-mmio
(i.e. '-device virtio-{blk,net,scsi,...}-device') is used for
storage/network/etc.

Optional pcie support is available and any pcie device supported by
QEMU can be plugged in (including virtio-pci if you prefer that over
virtio-mmio).

https://qemu.readthedocs.io/en/latest/system/i386/microvm.html
https://www.kraxel.org/blog/2020/10/qemu-microvm-acpi/

design issues
-------------

Not fully clear yet how to do hardware detection best.  Right now
using device tree to find virtio-mmio devices and pcie host bridge,
can reuse existing ArmVirtPkg code that way.  Needs patched QEMU.

features
--------
 [working] serial console
 [working] direct kernel boot
 [working] virtio-mmio support
 [in progress] pcie support

known limitations
-----------------
 * rtc=on is required for now.
 * can't use separate code/vars (actually an microvm limitation,
   there is no pflash support).
 * transitional virtio-pci devices do not work.  microvm doesn't
   support ioports on pcie, and ovmf doesn't initialize pcie devices
   with ioports if there is no address space for them (even though
   pcie devices are required to be functional without ioports).

usage
-----
qemu-system-x86_64 \
    -nographic \
    -machine microvm,acpi=on,pit=off,pic=off,rtc=on \
    -bios /path/to/MICROVM.fd \
    [ ... more args here ... ]