On 16/03/2011 02:58, "Mukesh Rathor" <mukesh.rathor@oracle.com>
wrote:
> Hi,
>
> I always wonder about intel vmcs info tracking when i have to look at
> it. Following data structs are used to keep track of it:
>
> static DEFINE_PER_CPU(struct foreign_vmcs, foreign_vmcs)
Used to track if a CPU is currently running on non-current vcpu''s vmcs.
Only
used by dom0 and stubdoms really right now. But plausibly a HVM VCPU could
do this to another HVM VCPU in future. The logic is there for that right
now.
> v->arch.hvm_vmx.active_cpu;
> v->arch.hvm_vmx.active_list;
These are actually used, in cpu offline, for one thing (in the case of the
per-cpu vmcs list). Did you actually read the code?
> static DEFINE_PER_CPU(struct vmcs_struct *, current_vmcs);
It is not true that current==v <=> current_vmcs==v''s vmcs. Again,
read the
code.
There are a few bits of state here it''s true but they are used pretty
much
entirely and straightforwardly in vmcs.c. You''re not going to get much
simplification without making things slower and/or *less* obvious and/or
introducing subtle bugs. Leave alone.
-- Keir
> It appears to me that it could be lot simpler. All we need to worry about
is
> if a cpu needs to be launched or resumed. The rest can be concluded
> from existing information. For example, current_vmcs and foreign_vmcs
> seems redundant. If current == v, then we can conclude current_vmcs is
> current, and forieng vmcs is not current! It seems all we need is
> unsetting launched in vmpclear.
>
> Can someone from Intel tell me what am I missing?
>
> thanks
> Mukesh
>
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