----- Original Message ----- > From: "Radim Krčmář" <[email protected]> > To: "James Hogan" <[email protected]> > Cc: "Paolo Bonzini" <[email protected]>, [email protected], > [email protected], "Christoffer Dall" > <[email protected]>, "Andrew Jones" <[email protected]>, "Marc Zyngier" > <[email protected]>, "Christian > Borntraeger" <[email protected]>, "Cornelia Huck" > <[email protected]>, "Paul Mackerras" > <[email protected]> > Sent: Wednesday, April 12, 2017 3:31:24 AM > Subject: Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in > kvm_make_all_cpus_request() > > 2017-04-11 10:37+0100, 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).
Yeah, I meant "it's wrong in Radim's patches". Not hard to fix though. Thanks for the review! Paolo > I agree, thanks for noticing this. It would be a huge mistake to drop > the synchronization. >
