From: Paolo Bonzini <pbonzini@redhat.com>
To: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: James Hogan <james.hogan@imgtec.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
Christoffer Dall <cdall@linaro.org>,
Andrew Jones <drjones@redhat.com>,
Marc Zyngier <marc.zyngier@arm.com>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Cornelia Huck <cornelia.huck@de.ibm.com>,
Paul Mackerras <paulus@ozlabs.org>
Subject: Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in kvm_make_all_cpus_request()
Date: Tue, 11 Apr 2017 15:45:40 -0400 (EDT) [thread overview]
Message-ID: <705609620.12874765.1491939940525.JavaMail.zimbra@redhat.com> (raw)
In-Reply-To: <20170411193124.GA395@potion>
----- Original Message -----
> From: "Radim Krčmář" <rkrcmar@redhat.com>
> To: "James Hogan" <james.hogan@imgtec.com>
> Cc: "Paolo Bonzini" <pbonzini@redhat.com>, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, "Christoffer Dall"
> <cdall@linaro.org>, "Andrew Jones" <drjones@redhat.com>, "Marc Zyngier" <marc.zyngier@arm.com>, "Christian
> Borntraeger" <borntraeger@de.ibm.com>, "Cornelia Huck" <cornelia.huck@de.ibm.com>, "Paul Mackerras"
> <paulus@ozlabs.org>
> 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.
>
next prev parent reply other threads:[~2017-04-11 19:45 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-06 20:20 [PATCH 0/6] KVM: towards maintainable kvm_make_all_cpus_request() Radim Krčmář
2017-04-06 20:20 ` [PATCH RFC 1/6] KVM: fix guest_mode optimization in kvm_make_all_cpus_request() Radim Krčmář
2017-04-06 21:02 ` James Hogan
2017-04-10 15:59 ` Andrew Jones
2017-04-11 10:43 ` James Hogan
2017-04-11 5:25 ` Paolo Bonzini
2017-04-11 9:37 ` James Hogan
2017-04-11 19:31 ` Radim Krčmář
2017-04-11 19:45 ` Paolo Bonzini [this message]
2017-04-11 20:45 ` Radim Krčmář
2017-04-12 0:15 ` Paolo Bonzini
2017-04-07 10:47 ` Christian Borntraeger
2017-04-06 20:20 ` [PATCH 2/6] KVM: use kvm_{test,clear}_request instead of {test,clear}_bit Radim Krčmář
2017-04-07 10:55 ` Christian Borntraeger
2017-04-07 12:24 ` Radim Krčmář
2017-04-07 14:05 ` Radim Krčmář
2017-04-06 20:20 ` [PATCH 3/6] KVM: x86: use kvm_make_request instead of set_bit Radim Krčmář
2017-04-07 8:18 ` David Hildenbrand
2017-04-06 20:20 ` [PATCH 4/6] KVM: remove #ifndef CONFIG_S390 around kvm_vcpu_wake_up Radim Krčmář
2017-04-07 11:01 ` Christian Borntraeger
2017-04-06 20:20 ` [PATCH RFC 5/6] KVM: mark requests that do not need a wakeup Radim Krčmář
2017-04-07 8:27 ` Marc Zyngier
2017-04-07 12:29 ` Radim Krčmář
2017-04-06 20:20 ` [PATCH 6/6] KVM: perform a wake_up in kvm_make_all_cpus_request Radim Krčmář
2017-04-10 11:14 ` Andrew Jones
2017-04-11 5:34 ` Paolo Bonzini
2017-04-11 12:04 ` Andrew Jones
2017-04-11 5:37 ` Paolo Bonzini
2017-04-11 8:55 ` Paolo Bonzini
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