Re: [PATCH] KVM: PPC: Book3S HV: Drop locks around call to kvmppc_pin_guest_page

[Avi Kivity <avi@redhat.com>]

On 06/19/2012 01:50 PM, Alexander Graf wrote:
> 
> On 06.06.2012, at 17:52, Alexander Graf wrote:
> 
>> 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?
> 
> Avi?

Sorry!  Applied to master, will push upstream shortly.

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