[Bug]: System assertion failure occurs upon restart after OS installation using WHPX, or when the 'Reset' option is triggered from the QEMU application

[ponchendilan]

Is there an existing issue for this?

• I have searched existing issues

Bug Type

• Firmware
• Tool
• Unit Test

What packages are impacted?

OvmfPkg

Which targets are impacted by this bug?

DEBUG

Current Behavior

When WHPX is used to accelerate the navigation speed in an already installed ubuntu-22.04.5 OS, on giving 'restart' the following assert is obtained.

The assert happens even when 'reset' is given from Qemu application.

ASSERT E:\Qemu_22\EDK2\OvmfPkg\Library\PlatformInitLib\MemDetect.c(1325): (MtrrSettings.MtrrDefType & 0x00000400) == 0

Note: This issue happens only when WHPX is enabled

Expected Behavior

System should restart properly when 'restart' or 'reset' is given from OS and Qemu application respectively.

Steps To Reproduce

Host Operating System: Windows 11
Toolchain: VS2022
Qemu application : 10.0.0

1. Install ubunu-22.04.5 OS.
2. Use the following command to launch OS and verify navigation speed. As WHPX is enabled the navigation speed will be good.
   qemu-system-x86_64 -bios E:\Qemu_22\EDK2\Build\OvmfX64\DEBUG_VS2022\FV\OVMF.fd -m 2048 -serial stdio -M accel=whpx -hda E:\Qemu_22\OS_Installattion_X64\img_ubuntu_22_5.img -debugcon file:E:\Qemu_22\OS_Installation_log\Debug_Maccel_1.log -global isa-debugcon.iobase=0x402
3. Give 'Restart' from OS.
   Alternate method
   Give 'Reset' from Qemu application while the OS is getting loaded.

The Assert will happen when either of the above is tried.

Build Environment

- OS(s): (Host) Windows 11
- Tool Chain(s):VS2022
- Qemu Apllication : 10.0.0

Version Information

edk2-stable202505 tag

Urgency

Medium

Are you going to fix this?

Someone else needs to fix it

Do you need maintainer feedback?

Maintainer feedback requested

Anything else?

Attaching log for reference.

Debug_Maccel.log

[lersek]

This seems to me like an emulation bug in WHPX (or in QEMU's WHPX accelerator). The Intel SDM (Order Number: 325462-088US, June 2025) writes, in 13.11 MEMORY TYPE RANGE REGISTERS (MTRRS):

Following a hardware reset, the P6 and more recent processor families disable all the fixed and variable MTRRs, [...]

and in 13.11.2.1 IA32_MTRR_DEF_TYPE MSR,

FE (fixed MTRRs enabled) flag, bit 10 — Fixed-range MTRRs are enabled when set; fixed-range MTRRs are disabled when clear. [...]

This means that SecMtrrSetup in OvmfPkg/Sec/SecMain.c is expected to read, and to write back, a zero DefType.Bits.FE (bit#10). Consequently,

ASSERT ((MtrrSettings.MtrrDefType & BIT10) == 0);

in PlatformQemuInitializeRam in OvmfPkg/Library/PlatformInitLib/MemDetect.c should pass.

[lgao4]

@ponchendilan , please base on the feedback to continue.