Re: [Xen-devel] [PATCH 00/13] Add VMX TSC scaling support

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 28/09/15 08:13, Haozhong Zhang wrote:
> This patchset adds support for VMX TSC scaling feature which is
> available on Intel Skylake CPU. The specification of VMX TSC scaling
> can be found at
> http://www.intel.com/content/www/us/en/processors/timestamp-counter-scaling-virtualization-white-paper.html
>
> VMX TSC scaling allows guest TSC which is read by guest rdtsc(p)
> instructions increases in a rate that is customized by the hypervisor
> and can be different than the host TSC rate. Basically, VMX TSC
> scaling adds a 64-bit field called TSC multiplier in VMCS so that, if
> VMX TSC scaling is enabled, TSC read by guest rdtsc(p) instructions
> will be calculated by the following formula:
>
>   guest EDX:EAX = (Host TSC * TSC multiplier) >> 48 + VMX TSC Offset
>
> where, Host TSC = Host MSR_IA32_TSC + Host MSR_IA32_TSC_ADJUST.
>
> This patchset is composed of following four parts.
>   1. PATCH 01 - 02 fix bugs in tsc_get_info() which could result in
>      errors when VMX TSC scaling is used.
>      
>   2. PATCH 03 - 09 add/move the common parts of VMX TSC scaling and
>      SVM TSC ratio to hvm.c and x86/time.c.
>      
>   3. PATCH 10 - 12 implement the VMX-specific code for supporting VMX
>      TSC scaling.
>      
>   4. PATCH 13 adapts libxl for VMX TSC scaling (as well as SVM TSC
>      ratio).

Thankyou for this series.  I have had a brief look over it and it
appears to be in good shape, but have not done a thorough review yet.

Konrad/Boris: As Oracle are the main users of the more interesting guest
timing modes, do you have tests to verify correct functioning?

~Andrew

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel