github/acrn-hypervisor
1
0
Fork 0
mirror of https://github.com/projectacrn/acrn-hypervisor.git synced 2025-06-19 12:12:16 +00:00
Code Issues Projects Releases Wiki Activity

Doc: Add ART virtualization hld

Browse Source 
This patch adds ART virtualization hld.

Signed-off-by: Kaige Fu <kaige.fu@intel.com>
This commit is contained in:
Kaige Fu 2019-10-18 17:15:36 +08:00 committed by deb-intel
parent b3142e1600
commit 6f9367a50c
1 changed files with 28 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
doc/developer-guides/hld/hv-cpu-virt.rst
View File

@ -1221,6 +1221,34 @@ in *VMX_PROC_VM_EXEC_CONTROLS*):
- For read: ``val = rdtsc() + exec_vmread64(VMX_TSC_OFFSET_FULL)``
- For write: ``exec_vmwrite64(VMX_TSC_OFFSET_FULL, val - rdtsc())``
ART Virtualization
******************
The invariant TSC is based on the invariant timekeeping hardware (called
Always Running Timer or ART), that runs at the core crystal clock frequency.
The ratio defined by CPUID leaf 15H express the frequency relationship
between the ART hardware and TSC.
If CPUID.15H.EBX[31:0] != 0 and CPUID.80000007H:EDX[InvariantTSC] = 1, the
following linearity relationship holds between TSC and the ART hardware:
``TSC_Value = (ART_Value * CPUID.15H:EBX[31:0]) / CPUID.15H:EAX[31:0] + K``
Where `K` is an offset that can be adjusted by a privileged agent.
When ART hardware is reset, both invariant TSC and K are also reset.
The guideline of ART virtualization (vART) is that software in native can run in
VM too. The vART solution is:
- Present the ART capability to guest through CPUID leaf 15H for `CPUID.15H:EBX[31:0]`
and `CPUID.15H:EAX[31:0]`.
- Passthrough devices see the physical ART_Value (vART_Value = pART_Value)
- Relationship between the ART and TSC in guest is:
``vTSC_Value = (vART_Value * CPUID.15H:EBX[31:0]) / CPUID.15H:EAX[31:0] + vK``
Where `vK = K + VMCS.TSC_OFFSET`.
- If `vK` or `vTSC_Value` are changed by guest, we change the `VMCS.TSC_OFFSET` accordingly.
- `K` should never be changed by hypervisor.
XSAVE Emulation
***************