[Feature request] x86: dump MSR features in human form

[Philippe Mathieu-Daudé]

QEMU might fail because host/guest cpu features are not properly configured:

qemu-system-x86_64: error: failed to set MSR 0x48f to 0x7fefff00036dfb
qemu-system-x86_64: /root/qemu-master/target/i386/kvm.c:2695:
kvm_buf_set_msrs: Assertion `ret == cpu->kvm_msr_buf->nmsrs' failed.

To ease debugging, it the MSR features bit could be dumped.

Example in this thread:

https://lists.gnu.org/archive/html/qemu-devel/2020-05/msg05593.html

  The high 32 bits are 0111 1111 1110 1111 1111 1111.

  The low 32 bits are 0000 0011 0110 1101 1111 1011.

  The features that are set are the xor, so 0111 1100 1000 0010 0000 0100:

  - bit 2, vmx-exit-nosave-debugctl
  - bit 9, host address space size, is handled automatically by QEMU
  - bit 15, vmx-exit-ack-intr
  - bit 17, vmx-exit-save-pat
  - bit 18, vmx-exit-load-pat
  - bit 19, vmx-exit-save-efer
  - bit 20, vmx-exit-load-efer
  - bit 21, vmx-exit-save-preemption-timer

This output ^^^ is easier to digest.

[Philippe Mathieu-Daudé (philmd)]

This is an automated cleanup. This bug report has been moved to QEMU's
new bug tracker on gitlab.com and thus gets marked as 'invalid' now.
Please continue with the discussion here:

 https://gitlab.com/qemu-project/qemu/-/issues/237