Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in kvm_make_all_cpus_request()

[James Hogan]

Hi Paolo,

On Tue, Apr 11, 2017 at 01:25:04PM +0800, Paolo Bonzini wrote:
> On 07/04/2017 05:02, James Hogan wrote:
> > This presumably changes the behaviour on x86, from != OUTSIDE_GUEST_MODE
> > to == IN_GUEST_MODE. so:
> > - you'll no longer get IPIs if its in READING_SHADOW_PAGE_TABLES (which
> >   MIPS also now uses when accessing mappings outside of guest mode and
> >   depends upon to wait until the old mappings are no longer in use).
> 
> This is wrong, the purpose of READING_SHADOW_PAGE_TABLES is "kvm_flush_remote_tlbs
> should send me an IPI, because I want to stop kvm_flush_remote_tlbs until I'm done
> reading the page tables".

That sounds equivalent to what I meant for MIPS, i.e.
kvm_flush_remote_tlbs() does the waiting (not the thing accessing guest
mappings).

Cheers
James

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