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>
Subject: Re: [PATCH RFC 1/6] KVM: fix guest_mode optimization in kvm_make_all_cpus_request()
Date: Tue, 11 Apr 2017 21:31:24 +0200 [thread overview]
Message-ID: <20170411193124.GA395@potion> (raw)
In-Reply-To: <20170411093726.GA31606@jhogan-linux.le.imgtec.org>
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).
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 19:31 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 [this message]
2017-04-11 19:45 ` Paolo Bonzini
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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