From: Avi Kivity <avi@redhat.com>
To: "Nikunj A. Dadhania" <nikunj@linux.vnet.ibm.com>
Cc: peterz@infradead.org, mingo@elte.hu, jeremy@goop.org,
mtosatti@redhat.com, kvm@vger.kernel.org, x86@kernel.org,
vatsa@linux.vnet.ibm.com, linux-kernel@vger.kernel.org,
hpa@zytor.com
Subject: Re: [RFC PATCH v1 3/5] KVM: Add paravirt kvm_flush_tlb_others
Date: Sun, 29 Apr 2012 15:23:16 +0300 [thread overview]
Message-ID: <4F9D32B4.8040002@redhat.com> (raw)
In-Reply-To: <20120427162401.27082.59387.stgit@abhimanyu>
On 04/27/2012 07:24 PM, Nikunj A. Dadhania wrote:
> flush_tlb_others_ipi depends on lot of statics in tlb.c. Replicated
> the flush_tlb_others_ipi as kvm_flush_tlb_others to further adapt to
> paravirtualization.
>
> Use the vcpu state information inside the kvm_flush_tlb_others to
> avoid sending ipi to pre-empted vcpus.
>
> * Do not send ipi's to offline vcpus and set flush_on_enter flag
get_user_pages_fast() depends on the IPI to hold off page table teardown
while they are locklessly walked with interrupts disabled. If a vcpu
were to be preempted while in this critical section, another vcpu
tearing down page tables would go ahead and destroy them. when the
preempted vcpu resumes it then touches the freed pages.
We could try to teach kvm and get_user_pages_fast() about this, but this
is intrusive. Another option is to replace the cpu_relax() loop with
something that sleeps and is then woken up by the TLB IPI handler if needed.
> * For online vcpus: Wait for them to clear the flag
>
>
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-04-29 12:23 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-27 16:23 [RFC PATCH v1 0/5] KVM paravirt remote flush tlb Nikunj A. Dadhania
2012-04-27 16:23 ` [RFC PATCH v1 1/5] KVM Guest: Add VCPU running/pre-empted state for guest Nikunj A. Dadhania
2012-05-01 1:03 ` Raghavendra K T
2012-05-01 3:25 ` Nikunj A Dadhania
2012-04-27 16:23 ` [RFC PATCH v1 2/5] KVM-HV: " Nikunj A. Dadhania
2012-04-27 16:24 ` [RFC PATCH v1 3/5] KVM: Add paravirt kvm_flush_tlb_others Nikunj A. Dadhania
2012-04-29 12:23 ` Avi Kivity [this message]
2012-05-01 3:34 ` Nikunj A Dadhania
2012-05-01 9:39 ` Peter Zijlstra
2012-05-01 10:47 ` Avi Kivity
2012-05-01 10:57 ` Peter Zijlstra
2012-05-01 10:59 ` Peter Zijlstra
2012-05-01 22:49 ` Jeremy Fitzhardinge
2012-05-03 14:09 ` Stefano Stabellini
2012-05-01 12:12 ` Avi Kivity
2012-05-01 14:59 ` Peter Zijlstra
2012-05-01 15:31 ` Avi Kivity
2012-05-01 15:36 ` Peter Zijlstra
2012-05-01 15:39 ` Avi Kivity
2012-05-01 15:42 ` Peter Zijlstra
2012-05-01 15:11 ` Peter Zijlstra
2012-05-01 15:33 ` Avi Kivity
2012-05-01 15:14 ` Peter Zijlstra
2012-05-01 15:36 ` Avi Kivity
2012-05-01 16:16 ` Peter Zijlstra
2012-05-01 16:43 ` Paul E. McKenney
2012-05-01 16:18 ` Peter Zijlstra
2012-05-01 16:20 ` Peter Zijlstra
2012-05-02 8:51 ` Nikunj A Dadhania
2012-05-02 10:20 ` Peter Zijlstra
2012-05-02 13:53 ` Nikunj A Dadhania
2012-05-04 4:32 ` Nikunj A Dadhania
2012-05-04 11:44 ` Srivatsa Vaddagiri
2012-05-07 3:10 ` Nikunj A Dadhania
2012-04-27 16:26 ` [RFC PATCH v1 4/5] KVM: get kvm_kick_vcpu out for pv_flush Nikunj A. Dadhania
2012-04-27 16:27 ` [RFC PATCH v1 5/5] KVM: Introduce PV kick in flush tlb Nikunj A. Dadhania
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