* [PATCH] KVM: document lock orders
@ 2016-10-13 11:10 Paolo Bonzini
2016-10-13 12:51 ` Radim Krčmář
0 siblings, 1 reply; 2+ messages in thread
From: Paolo Bonzini @ 2016-10-13 11:10 UTC (permalink / raw)
To: linux-kernel, kvm; +Cc: rkrcmar
This is long overdue, and not really hard.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
Documentation/virtual/kvm/locking.txt | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index f2491a8c68b4..e5dd9f4d6100 100644
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -4,7 +4,17 @@ KVM Lock Overview
1. Acquisition Orders
---------------------
-(to be written)
+The acquisition orders for mutexes are as follows:
+
+- kvm->lock is taken outside vcpu->mutex
+
+- kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock
+
+- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
+ them together is quite rare.
+
+For spinlocks, kvm_lock is taken outside kvm->mmu_lock. Everything
+else is a leaf: no other lock is taken inside the critical sections.
2: Exception
------------
--
2.7.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] KVM: document lock orders
2016-10-13 11:10 [PATCH] KVM: document lock orders Paolo Bonzini
@ 2016-10-13 12:51 ` Radim Krčmář
0 siblings, 0 replies; 2+ messages in thread
From: Radim Krčmář @ 2016-10-13 12:51 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: linux-kernel, kvm
2016-10-13 13:10+0200, Paolo Bonzini:
> This is long overdue, and not really hard.
>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
Applied to kvm/queue, thanks.
> Documentation/virtual/kvm/locking.txt | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
> index f2491a8c68b4..e5dd9f4d6100 100644
> --- a/Documentation/virtual/kvm/locking.txt
> +++ b/Documentation/virtual/kvm/locking.txt
> @@ -4,7 +4,17 @@ KVM Lock Overview
> 1. Acquisition Orders
> ---------------------
>
> -(to be written)
> +The acquisition orders for mutexes are as follows:
> +
> +- kvm->lock is taken outside vcpu->mutex
> +
> +- kvm->lock is taken outside kvm->slots_lock and kvm->irq_lock
> +
> +- kvm->slots_lock is taken outside kvm->irq_lock, though acquiring
> + them together is quite rare.
> +
> +For spinlocks, kvm_lock is taken outside kvm->mmu_lock. Everything
> +else is a leaf: no other lock is taken inside the critical sections.
>
> 2: Exception
> ------------
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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