From: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
To: Peter Zijlstra <peterz@infradead.org>, Avi Kivity <avi@redhat.com>
Cc: 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: Wed, 02 May 2012 14:21:14 +0530 [thread overview]
Message-ID: <87obq7ge4d.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1335865176.13683.120.camel@twins>
On Tue, 01 May 2012 11:39:36 +0200, Peter Zijlstra <peterz@infradead.org> wrote:
> On Sun, 2012-04-29 at 15:23 +0300, Avi Kivity wrote:
> > 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.
>
> I think something like
>
> select HAVE_RCU_TABLE_FREE if PARAVIRT
>
> or somesuch is just about all it takes.
>
[root@krm1 linux]# grep HAVE_RCU_TABLE .config
CONFIG_HAVE_RCU_TABLE_FREE=y
[root@krm1 linux]# make -j32 -s
mm/memory.c: In function ‘tlb_remove_table_one’:
mm/memory.c:315: error: implicit declaration of function ‘__tlb_remove_table’
I suppose we need to have __tlb_remove_table. Trying to understand what
needs to be done there.
Regards
Nikunj
next prev parent reply other threads:[~2012-05-02 8:51 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
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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87obq7ge4d.fsf@linux.vnet.ibm.com \
--to=nikunj@linux.vnet.ibm.com \
--cc=avi@redhat.com \
--cc=hpa@zytor.com \
--cc=jeremy@goop.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=mtosatti@redhat.com \
--cc=peterz@infradead.org \
--cc=vatsa@linux.vnet.ibm.com \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).