Re: [Qemu-devel] [PATCH v3 2/3] target-ppc: add flag in chech_tlb_flush()

[David Gibson]

On Wed, Sep 14, 2016 at 02:37:03PM +1000, Benjamin Herrenschmidt wrote:
> On Wed, 2016-09-14 at 09:23 +0530, Nikunj A Dadhania wrote:
> 
> Hr... this is confusing, let me rephrase ;-)
> 
> > Due to lazy tlb flushes, propagation of the tlb flush is delayed.
> Moreover, certain operations need to do broadcast flush, this too can
> be
> > delayed until we hit the operation that warrant a broadcast.
> 
> Instead:
> 
> We flush the qemu TLB lazily. check_tlb_flush is called whenever we
> hit a context synchronizing event or instruction that requires a pending
> flush to be performed.
> 
> However, we fail to handle broadcast TLB flush operations. In order
> to fix that efficiently, we want to differenciate whether check_tlb_flush()
> needs to only apply pending local flushes (isync instructions,
> interrupts, ...) or also global pending flush operations. The latter
> is only needed when executing instructions that are defined architecturally
> as synchronizing global TLB flush operations. This in our case is ptesync
> on BookS and tlbsync on BookE along with the paravirtualized hypervisor
> calls.

Nice.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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