linux/Documentation/virt/acrn/cpuid.rst
Shuo Liu c619a804cc docs: acrn: Introduce ACRN
Add documentation on the following aspects of ACRN:

  1) A brief introduction on the architecture of ACRN.
  2) I/O request handling in ACRN.
  3) CPUID functions of ACRN.

To learn more about ACRN, please go to ACRN project website
https://projectacrn.org, or the documentation page
https://projectacrn.github.io/.

Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Sen Christopherson <sean.j.christopherson@intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Fengwei Yin <fengwei.yin@intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Yu Wang <yu1.wang@intel.com>
Cc: Reinette Chatre <reinette.chatre@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Zhi Wang <zhi.a.wang@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Shuo Liu <shuo.a.liu@intel.com>
Link: https://lore.kernel.org/r/20210207031040.49576-2-shuo.a.liu@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-02-09 10:58:18 +01:00

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.. SPDX-License-Identifier: GPL-2.0
===============
ACRN CPUID bits
===============
A guest VM running on an ACRN hypervisor can check some of its features using
CPUID.
ACRN cpuid functions are:
function: 0x40000000
returns::
eax = 0x40000010
ebx = 0x4e524341
ecx = 0x4e524341
edx = 0x4e524341
Note that this value in ebx, ecx and edx corresponds to the string
"ACRNACRNACRN". The value in eax corresponds to the maximum cpuid function
present in this leaf, and will be updated if more functions are added in the
future.
function: define ACRN_CPUID_FEATURES (0x40000001)
returns::
ebx, ecx, edx
eax = an OR'ed group of (1 << flag)
where ``flag`` is defined as below:
================================= =========== ================================
flag value meaning
================================= =========== ================================
ACRN_FEATURE_PRIVILEGED_VM 0 guest VM is a privileged VM
================================= =========== ================================
function: 0x40000010
returns::
ebx, ecx, edx
eax = (Virtual) TSC frequency in kHz.