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SubjectRe: [PATCH ] Documentation/kvm: Update cpuid documentation for steal time and pv eoi
On Fri, Aug 23, 2013 at 05:34:47PM +0530, Raghavendra K T wrote:
> Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
> ---
> While adding documentation for pvspinlock, I found that these two should
> be updated. I have based this on top of pvspinlock kvm host patchset (V12)

I would change the description to merely say what the CPUID bits
mean, and what they mean is exactly that an MSR is valid.
Use KVM_FEATURE_ASYNC_PF as a template.


> Documentation/virtual/kvm/cpuid.txt | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
> index 22ff659..15a5ac20 100644
> --- a/Documentation/virtual/kvm/cpuid.txt
> +++ b/Documentation/virtual/kvm/cpuid.txt
> @@ -43,6 +43,15 @@ KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs
> KVM_FEATURE_ASYNC_PF || 4 || async pf can be enabled by
> || || writing to msr 0x4b564d02
> ------------------------------------------------------------------------------
> +KVM_FEATURE_STEAL_TIME || 5 || guest accounts fine granularity
> + || || task steal time.

I'm not sure what this phrase means.
Steal time is a host feature, not a guest feature:
IIUC if this bit is set, the hypervisor can pass the guest information
about how much time was spent running other processes outside the VM.

> enabled when
> + || || shedstat or task delay accounting
> + || || is supported by the host.

I think it's enabled by guest, not by host.


> +------------------------------------------------------------------------------
> +KVM_FEATURE_PV_EOI || 6 || overrides the generic EOI
> + || || implementation with an optimized
> + || || version.

More exactly "with a paravirtualized version".

> +------------------------------------------------------------------------------
> KVM_FEATURE_PV_UNHALT || 7 || guest checks this feature bit
> || || before enabling paravirtualized
> || || spinlock support.
> --
> 1.7.11.7


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