Re: [Xen-devel] [PATCH v2 02/13] Set VCPU's is_running flag closer to when the VCPU is dispatched

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 20.09.13 at 11:42, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> An interrupt handler happening during new VCPU scheduling may want to know
> who was on the (physical) processor at the point of the interrupt. Just
> looking at 'current' may not be accurate since there is a window of time when
> 'current' points to new VCPU and its is_running flag is set but the VCPU has
> not been dispatched yet. More importantly, on Intel processors, if the handler
> wants to examine certain state of an HVM VCPU (such as segment registers) the
> VMCS pointer is not set yet.
> 
> This patch will move setting the is_running flag to a later point.

As said on v1 already - I'm all but convinced that this is not going to
break something in subtle ways. Without you assuring us that you
carefully inspected _all_ uses of this flag, I don't think this can go in.

Jan


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