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    SubjectRe: [PATCH v2 6/6] Describe KVM_MSR_STEAL_TIME
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    On Sun, 2011-01-30 at 15:19 +0200, Avi Kivity wrote:
    > On 01/28/2011 09:52 PM, Glauber Costa wrote:
    > > This patch adds documentation about usage of the newly
    > > introduced KVM_MSR_STEAL_TIME.
    > >
    > >
    > > +
    > > +MSR_KVM_STEAL_TIME: 0x4b564d03
    > > +
    > > + data: 4-byte alignment physical address of a memory area which must be
    > > + in guest RAM, plus an enable bit in bit 0.
    >
    > 64-byte aligned:
    > - avoids wrapping around a page boundary, which may let us optimize
    > things later on (see kvm_write_guest_cached()).
    > - gives us 5 more unused bits to enable more options
    >
    > > This memory is expected to
    > > + hold a copy of the following structure:
    > > +
    > > + struct kvm_steal_time {
    > > + __u64 steal;
    > > + __u32 version;
    > > + __u32 flags;
    > > + __u32 pad[6];
    > > + }
    > > +
    > > + whose data will be filled in by the hypervisor periodically. Only one
    > > + write, or registration, is needed for each VCPU. The interval between
    > > + updates of this structure is arbitrary and implementation-dependent.
    > > + The hypervisor may update this structure at any time it sees fit until
    > > + anything with bit0 == 0 is written to it.
    > > +
    > > + Fields have the following meanings:
    > > +
    > > + version: guest has to check version before and after grabbing
    > > + time information and check that they are both equal and even.
    > > + An odd version indicates an in-progress update.
    > > +
    > > + flags: At this point, always zero. May be used to indicate
    > > + changes in this structure in the future.
    > > +
    > > + steal: the amount of time in which this vCPU did not run, in
    > > + nanoseconds.
    > > +
    >
    > The guest must initialize the entire 64-byte structure to zero before
    > enabling the feature.

    I honestly don't see why. But I also don't see why not...
    Will update it.




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