Qemu with -accel whpx doesn't set WRMSR permissions, which blocks nested virtualization
Description of problem:
This bug blocks https://gitlab.com/qemu-project/qemu/-/issues/628

Qemu doesn't set the host's Hyper-V permissions for WRMSR command to allow using SVM or VMX. Unset permissions lead to `unchecked MSR access error: WRMSR to 0xc0000080` inside Linux VM when trying to launch nested VM on real AMD cpu. Intel users do not see guest VMX feature at all. Please see **Additional info** section to understand how Hyper-V permissions for nested virtualization work in Windows.
Steps to reproduce:
1. Turn on VT-x (for Intel) or AMD-V virtualization in your real hardware BIOS/EFI. This was tested only on AMD cpu and Qemu 9, Intel \*may\* behave differently.
 2. Install any distro in qemu disk c:\\linux_disk.qcow2 with MSR enabled in kernel, for example, Ubuntu 22.04 LTS.
 3. Run qemu using `qemu-system-x86_64.exe -m 2048 -machine q35 -accel whpx -cpu Opteron_G5,check,+svm -hda c:\linux_disk.qcow2`

    To check if your distro has MSR mod enabled, run `grep -i msr /boot/config-$(uname -r)` and it should return `CONFIG_X86_MSR=m` or `CONFIG_X86_MSR=y`. If not, recompile and reinstall your kernel.
 4. Run `sudo modprobe msr` and then `sudo rdmsr 0xc0000080 #EFER`. You should see `d01` on modern AMD models. \[Untested\] For intel, run `sudo modprobe msr`, then `sudo rdmsr 0x3A`. You should see `5` or `0x5` or `0x100005`. d01 for AMD and 5 for Intel in output are necessary to enable nested VM. If RDMSR returns non-zero value, it means that qemu developers implemented this part of functionality and your Hyper-V on Windows is not broken.
 5. Run `cat /proc/cpuinfo | grep -c svm` on AMD cpu, which should output a positive digit.
 6. Run `sudo dmesg | grep kvm` and note:

    `[1.924036] kvm_amd: Nested Virtualization enabled`

    `[1.924038] kvm_amd: Nested Paging disabled`\
    `[1.924040] kvm_amd: PMU virtualization is disabled`
 7. This, in theory, is sufficient for KVM-acclelerated qemu to start a nested VM.
 8. Run `xhost si:localuser:root` to prevent `gtk initialization failed` error
 9. Run `sudo qemu-system-x86_64 -accel kvm`. A black window with "Guest has not initialized the display (yet)." appears.
10. Run `sudo dmesg` and note qemu crash starting with `unchecked MSR access error: WRMSR`

    \* Steps 1-4 are only required for diagnostics, and KVM works (in native Windows Hyper-V manager) without the necessarity to enter these commands in usual usage scenarios. If you run <span dir="">`cat /proc/cpuinfo | grep -c vmx` on Intel cpu</span> on Step 5, you may get zero. See Step 5 of Additional Info to understand why.

    \
    Microsoft released useful info about how to look into Hyper-V MSR access problems:\
    WRMSR research in Hyper-V - https://msrc.microsoft.com/blog/2018/12/first-steps-in-hyper-v-research/
Additional information:
By default, Hyper-V manager in Windows does not allow nested virtualization.\
To see what happens, do the following:

 1. Open Hyper-V manager built in the host Windows and create default Ubuntu 22.04 LTS suggested. Upon installation, shut down the VM. Note the name of the VM ("Ubuntu 22.04 LTS" by default).
 2. Open Powershell console in the host and run `Set-VMProcessor -VMName "Ubuntu 22.04 LTS" -ExposeVirtualizationExtensions $false`
 3. Launch guest Ubuntu 22.04 LTS, open its terminal and run `sudo dmesg | grep kvm`. No output.
 4. Run `sudo rdmsr 0xc0000080 #EFER` that outputs d01, which means that Hyper-V manager allows this **ring 0 level** operation.
 5. Run `cat /proc/cpuinfo | grep -c svm` for AMD or `cat /proc/cpuinfo | grep -c vmx`  for Intel. Note that output is `0`.
 6. Shut the VM down.
 7. Now, Open Powershell console and `run Set-VMProcessor -VMName "Ubuntu 22.04 LTS" -ExposeVirtualizationExtensions $true`
 8. Launch Ubuntu 22.04 LTS, open its terminal and run `sudo dmesg | grep kvm`. Output:

    `[2.369144] kvm: Nested Virtualization enabled`

    `[2.369146] SVM: kvm: Nested Paging enabled`

    `[2.369148] SVM: kvm: Hyper-V enlightened NPT TLB flush enabled`

    `[2.369149] SVM: kvm: Hyper-V Direct TLB flush enabled`

    `[2.369153] SVM: Virtual VMLOAD VMSAVE supported`
 9. Run `cat /proc/cpuinfo | grep -c svm` for AMD or `cat /proc/cpuinfo | grep -c vmx`  for Intel. Note that output is `1` or other positive digit, depending on the number of cpus you've assigned to the VM.
10. Run `xhost si:localuser:root` to prevent `gtk initialization failed` error
11. Run `sudo qemu-system-x86_64 -accel kvm` and it successfully boots into qemu BIOS.
12. Running `sudo qemu-system-x86_64 -accel kvm` calls WRMSR in background, so if you see\
    booted qemu BIOS in KVM, wrmsr was successfully called.