From: Alexander Graf <agraf@suse.de>
To: Avi Kivity <avi@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>,
kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH] KVM: PPC: Book3S HV: Drop locks around call to kvmppc_pin_guest_page
Date: Wed, 06 Jun 2012 17:52:46 +0200 [thread overview]
Message-ID: <4FCF7CCE.70308@suse.de> (raw)
In-Reply-To: <4FCF4D0B.9040309@redhat.com>
On 06/06/2012 02:28 PM, Avi Kivity wrote:
> On 06/01/2012 01:20 PM, Paul Mackerras wrote:
>> At the moment we call kvmppc_pin_guest_page() in kvmppc_update_vpa()
>> with two spinlocks held: the vcore lock and the vcpu->vpa_update_lock.
>> This is not good, since kvmppc_pin_guest_page() calls down_read() and
>> get_user_pages_fast(), both of which can sleep. This bug was introduced
>> in 2e25aa5f ("KVM: PPC: Book3S HV: Make virtual processor area
>> registration more robust").
>>
>> This arranges to drop those spinlocks before calling
>> kvmppc_pin_guest_page() and re-take them afterwards. Dropping the
>> vcore lock in kvmppc_run_core() means we have to set the vcore_state
>> field to VCORE_RUNNING before we drop the lock, so that other vcpus
>> won't try to run this vcore.
>>
>> Signed-off-by: Paul Mackerras<paulus@samba.org>
>> ---
>> Since this bug is in Linus' tree, and it can cause a scheduling while
>> atomic bug message, can we send this to Linus for inclusion in 3.5,
>> after review of course?
>>
> Sure, Alex?
Yup, reviewed and tested. Looks ready to go into the tree to me. Can you
pull it in the short way please?
Alex
Acked-by: Alexander Graf <agraf@suse.de>
next prev parent reply other threads:[~2012-06-06 15:52 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-06-01 10:20 [PATCH] KVM: PPC: Book3S HV: Drop locks around call to kvmppc_pin_guest_page Paul Mackerras
2012-06-06 12:28 ` Avi Kivity
2012-06-06 15:52 ` Alexander Graf [this message]
2012-06-19 10:50 ` Alexander Graf
2012-06-19 12:04 ` Avi Kivity
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