On Sun, Apr 21, 2013 at 12:35:08PM -0300, Marcelo Tosatti wrote:
> On Sun, Apr 21, 2013 at 12:27:51PM -0300, Marcelo Tosatti wrote:
> > On Sun, Apr 21, 2013 at 04:03:46PM +0300, Gleb Natapov wrote:
> > > On Tue, Apr 16, 2013 at 02:32:38PM +0800, Xiao Guangrong wrote:
> > > > This patchset is based on my previous two patchset:
> > > > [PATCH 0/2] KVM: x86: avoid potential soft lockup and unneeded mmu
> > > > reload
> > > > (https://lkml.org/lkml/2013/4/1/2)
> > > >
> > > > [PATCH v2 0/6] KVM: MMU: fast invalid all mmio sptes
> > > > (https://lkml.org/lkml/2013/4/1/134)
> > > >
> > > > Changlog:
> > > > V3:
> > > > completely redesign the algorithm, please see below.
> > > >
> > > This looks pretty complicated. Is it still needed in order to avoid soft
> > > lockups after "avoid potential soft lockup and unneeded mmu reload" patch?
> >
> > Do not want kvm_set_memory (cases: DELETE/MOVE/CREATES) to be
> > suspectible to:
> >
> > vcpu 1 | kvm_set_memory
> > create shadow page
> > nuke shadow page
> > create shadow page
> > nuke shadow page
> >
> > Which is guest triggerable behavior with spinlock preemption algorithm.
>
> Not only guest triggerable as in the sense of a malicious guest,
> but condition above can be induced by host workload with non-malicious
> guest system.
>
Is the problem that newly created shadow pages are immediately zapped?
Shouldn't generation number/kvm_mmu_zap_all_invalid() idea described here
https://lkml.org/lkml/2013/4/22/111 solve this?
> Also kvm_set_memory being relatively fast with huge memory guests
> is nice (which is what Xiaos idea allows).
>
--
Gleb.
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