Re: [PATCH v2 3/4] KVM: cleanup: remove kvm_get_dirty_log()

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On 06/23/2010 12:01 PM, Takuya Yoshikawa wrote:
(2010/06/23 17:48), Avi Kivity wrote:

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 801d9f3..bea6f7c 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -1185,28 +1185,43 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_memory_slot *memslot;
struct kvm_vcpu *vcpu;
ulong ga, ga_end;
- int is_dirty = 0;
- int r;
+ unsigned long is_dirty = 0;
+ int r, i;
unsigned long n;


- r = kvm_get_dirty_log(kvm, log,&is_dirty);
- if (r)
+ r = -EINVAL;
+ if (log->slot>= KVM_MEMORY_SLOTS)
+ goto out;
+ memslot =&kvm->memslots->memslots[log->slot];

Not introduced by this patch, but shouldn't this use rcu_dereference()?

I was thinking like that, but sorry I don't know well about ppc.

My final goal is to make everything except

  /* If nothing is dirty, don't bother messing with page tables. */

part arch independent, so that we can concentrate on the truely
dirty logging things in the future.

So, making ppc code same as x86, rcu_dereference() for example , really
helps me.

Do you like this approach?

Well yes, I expect that not using rcu_dereference() (and srcu_read_lock()) is a bug here.


On a related note, I'd like to consolidate rcu locking:

- all vcpu ioctls take srcu_read_lock() when they start and drop it at the end. - KVM_VCPU_RUN drops the lock when sleeping and entering the guest (also on context switch?)

error compiling committee.c: too many arguments to function

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