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Re: [Xen-devel] [PATCH RFC V10 15/18] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor
- To: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
- From: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
- Date: Wed, 17 Jul 2013 00:19:42 +0530
- Cc: jeremy@xxxxxxxx, gregkh@xxxxxxx, kvm@xxxxxxxxxxxxxxx, linux-doc@xxxxxxxxxxxxxxx, drjones@xxxxxxxxxx, virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx, andi@xxxxxxxxxxxxxx, hpa@xxxxxxxxx, stefano.stabellini@xxxxxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxx, Gleb Natapov <gleb@xxxxxxxxxx>, x86@xxxxxxxxxx, agraf@xxxxxxx, mingo@xxxxxxxxxx, habanero@xxxxxxxxxxxxxxxxxx, ouyang@xxxxxxxxxxx, avi.kivity@xxxxxxxxx, tglx@xxxxxxxxxxxxx, chegu_vinod@xxxxxx, mtosatti@xxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, srivatsa.vaddagiri@xxxxxxxxx, attilio.rao@xxxxxxxxxx, pbonzini@xxxxxxxxxx, torvalds@xxxxxxxxxxxxxxxxxxxx
- Delivery-date: Tue, 16 Jul 2013 18:47:16 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On 07/16/2013 09:18 PM, Peter Zijlstra wrote:
On Tue, Jul 16, 2013 at 09:02:15AM +0300, Gleb Natapov wrote:
BTW can NMI handler take spinlocks?
No -- that is, yes you can using trylock, but you still shouldn't.
Thanks Peter for the clarification.
I had started checking few of nmi handlers code to confirm.
Did saw a raw spinlock in drivers/acpi/apei/ghes.c, but then stopped.
If it can what happens if NMI is
delivered in a section protected by local_irq_save()/local_irq_restore()?
You deadlock.
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