[Bug 216046] New: KVM_BUG_ON(vmx->nested.nested_run_pending, vcpu->kvm) when booting nested guest Windows 7 on another disk

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=216046

            Bug ID: 216046
           Summary: KVM_BUG_ON(vmx->nested.nested_run_pending, vcpu->kvm)
                    when booting nested guest Windows 7 on another disk
           Product: Virtualization
           Version: unspecified
    Kernel Version: 5.17.8-200.fc35.x86_64
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: kvm
          Assignee: virtualization_kvm@kernel-bugs.osdl.org
          Reporter: ercli@ucdavis.edu
        Regression: No

Created attachment 301072
  --> https://bugzilla.kernel.org/attachment.cgi?id=301072&action=edit
Guest hypervisor to reproduce this bug (xz compressed)

Reproducible host configuration 1:
    CPU model: Intel(R) Core(TM) i7-4510U CPU @ 2.00GHz
    Host kernel version: 5.17.8-200.fc35.x86_64

Reproducible host configuration 2:
    CPU model: 11th Gen Intel(R) Core(TM) i7-1185G7 @ 3.00GHz
    Host kernel version: 5.17.9

Host kernel arch: x86_64
Guest: a micro-hypervisor (called XMHF, 64-bits), which runs Windows 7 or
Windows 10 BIOS mode boot loader (32-bits).
QEMU command line: qemu-system-x86_64 -m 512M -cpu Haswell,vmx=yes -enable-kvm
-serial stdio -drive media=disk,file=c.img,index=1 -drive
media=disk,file=w.img,index=2
This bug still exists if using -machine kernel_irqchip=off
This problem cannot be tested with -accel tcg , because the guest requires
nested virtualization

How to reproduce:

1. Install Windows 7 or Windows 10 in QEMU. Use MBR and BIOS (i.e. do not use
GPT and UEFI). For example, I installed Windows on a 32G disk, and it results
in around 3 partitions: 50M, 31.5G (this is C:), 450M. Only the MBR header
(around 1 M) and the 50M disk is needed. For example,
https://drive.google.com/uc?id=1mLvKsPSuLbeckwcdnavnQMu8QxOwvX29 can be used to
reproduce this bug. Suppose Windows is installed in w.img.

2. Obtain c.img. c.img (8M) is uploaded at
https://drive.google.com/uc?id=1g3c9KMAoh_Yvb9bzSuOBMG5L-2VX6twU . It is also
compressed as c.img.xz and uploaded with this bug. It is built from
https://github.com/lxylxy123456/uberxmhf/tree/ab7968ed8017f43978081862526636f75c80a3b7
.

3. Start QEMU using the command line above.

4. BIOS will boot the micro-hypervisor (XMHF), then XMHF boots Windows as a
guest. After a little bit see error:

error: kvm run failed Input/output error
EAX=00000020 EBX=0000ffff ECX=00000000 EDX=0000ffff
ESI=00000000 EDI=00002300 EBP=00000000 ESP=00006d8c
EIP=00000018 EFL=00000046 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =f000 000f0000 ffffffff 00809300
CS =cb00 000cb000 ffffffff 00809b00
SS =0000 00000000 ffffffff 00809300
DS =0000 00000000 ffffffff 00809300
FS =0000 00000000 ffffffff 00809300
GS =0000 00000000 ffffffff 00809300
LDT=0000 00000000 0000ffff 00008200
TR =0000 00000000 0000ffff 00008b00
GDT=     00000000 00000000
IDT=     00000000 000003ff
CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000
DR3=0000000000000000 
DR6=00000000ffff0ff0 DR7=0000000000000400
EFER=0000000000000000
Code=0e 07 31 c0 b9 00 10 8d 3e 00 03 fc f3 ab 07 b8 20 00 e7 7e <cb> 0f 1f 80
00 00 00 00 6b 76 6d 20 61 50 69 43 20 00 00 00 2d 02 00 00 d9 02 00 00 00 03
KVM_GET_CLOCK failed: Input/output error
Aborted (core dumped)

After doing some print debugging on "Reproducible host configuration 2", with
Linux kernel version 5.17.9, I get the call stack of this bug

QEMU: ioctl(..., KVM_RUN, ...)
  kvm_vcpu_ioctl()
    kvm_arch_vcpu_ioctl_run()
      vcpu_run()
        vcpu_enter_guest()
          vmx_handle_exit() (static_call(kvm_x86_handle_exit))
            __vmx_handle_exit()
              KVM_BUG_ON(vmx->nested.nested_run_pending, vcpu->kvm)

That is, line 6038 in __vmx_handle_exit() is reached with
vmx->nested.nested_run_pending = 1

  6032          /*
  6033           * KVM should never reach this point with a pending nested
VM-Enter.
  6034           * More specifically, short-circuiting VM-Entry to emulate L2
due to
  6035           * invalid guest state should never happen as that means KVM
knowingly
  6036           * allowed a nested VM-Enter with an invalid vmcs12.  More
below.
  6037           */
  6038          if (KVM_BUG_ON(vmx->nested.nested_run_pending, vcpu->kvm))
  6039                  return -EIO;

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