Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Thu, Jun 01, 2006 at 11:46:05AM +0800, Xu, Anthony wrote:
> >From: Isaku Yamahata [mailto:yamahata@xxxxxxxxxxxxx]
> >Sent: 2006?6?1? 10:12
> >To: Xu, Anthony
> >Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: Re: [Xen-ia64-devel][PATCH] Enable SMP on VTI domain.
> >
> >
> >On Wed, May 31, 2006 at 03:32:06PM +0800, Xu, Anthony wrote:
> >> This patch intends to enable SMP on VTI domain.
> >>
> >> This patch depends on previous three patches I sent out.
> >> 1. fixed a bug which causes Oops
> >> 2. fixed a small bug about VTLB
> >> 3. Add sal emulation to VTI domain
> >>
> >> This patch uses IPI to implement global purge.
> >
> >I just took a quick look at your patch though.
> >There is no protection to IPI.
> >Is it O.K? Does the use of IPI cause race?
> >
> Do you mean below code?
> #ifdef XEN
>       spin_lock(&call_lock);
> #else

I meant local_irq_save(), local_irq_restore(). masking ipi.


> Or you mean the protection of global purge.
> When a vcpu get IPI to purge TLB,
> What it does is to invalid the TLB entry in VHPT,
> but not remove the TLB entry.
> There is no race condition.

Is there any gurantee that the vcpu which recives IPI isn't touching VHPT?

-- 
yamahata

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