The "bios-tables-test" program in QEMU's test suite locates the RSD PTR
ACPI table in guest RAM, and (chasing pointers to other ACPI tables)
performs various sanity checks on the QEMU-generated and
firmware-installed tables.
Currently this set of test cases doesn't work with UEFI guests. The ACPI
spec defines distinct methods for OSPM to locate the RSD PTR on
traditional BIOS vs. UEFI platforms, and the UEFI method is more difficult
to implement from the hypervisor side with just raw guest memory access.
Add a UEFI application (to be booted in the UEFI guest) that populates a
small, MB-aligned structure in guest RAM. The structure begins with a
signature GUID. The hypervisor should loop over all MB-aligned pages in
guest RAM until one matches the signature GUID at offset 0, at which point
the hypervisor can fetch the RSDP address field(s) from the structure.
QEMU's test logic currently spins on a pre-determined guest address, until
that address assumes a magic value. The method described in this patch is
conceptually the same ("busy loop until match is found"), except there is
no hard-coded address. This plays a lot more nicely with UEFI guest
firmware (we'll be able to use the normal page allocation UEFI service).
Given the size of EFI_GUID (16 bytes -- 128 bits), mismatches should be
astronomically unlikely. In addition, given the typical guest RAM size for
such tests (128 MB), there are 128 locations to check in one iteration of
the "outer" loop, which shouldn't introduce an intolerable delay after the
guest stores the RSDP address(es), and then the GUID.
The GUID that the hypervisor should search for is
AB87A6B1-2034-BDA0-71BD-375007757785
Expressed as a byte array:
{
0xb1, 0xa6, 0x87, 0xab,
0x34, 0x20,
0xa0, 0xbd,
0x71, 0xbd, 0x37, 0x50, 0x07, 0x75, 0x77, 0x85
}
Note that in the patch, we define "gBiosTablesTestGuid" with all bits
inverted. This is a simple method to prevent the UEFI binary, which
incorporates "gBiosTablesTestGuid", from matching the actual GUID in guest
RAM.
The UEFI application is written against the edk2 framework, which was
introduced earlier as a git submodule. The next patch will provide build
scripts for maintainers.
The source code follows the edk2 coding style, and is licensed under the
2-clause BSDL (in case someone would like to include UefiTestToolsPkg
content in a different edk2 platform).
The "UefiTestToolsPkg.dsc" platform description file resolves the used
edk2 library classes to instances (= library implementations) such that
the UEFI binaries inherit no platform dependencies. They are expected to
run on any system that conforms to the UEFI-2.3.1 spec (which was released
in 2012). The arch-specific build options are carried over from edk2's
ArmVirtPkg and OvmfPkg platforms.
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Cc: Shannon Zhao <shannon.zhaosl@gmail.com>
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190204160325.4914-4-lersek@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Laszlo Ersek