Rusty Russell wrote:
> kvm_vm_ioctl_get_dirty_log scans bitmap to see it it's all zero, but
> doesn't use that information.
>
> Avi says:
> Looks like it was used to guard kvm_mmu_slot_remove_write_access();
> optimizing the case where the guest just leaves the screen alone (which
> it usually does, especially in benchmarks).
>
> I'd rather reinstate that optimization. See
> 66d8a4e4d4bd470216028daabb9d887b73259c96 where the damage was done.
>
> It's pretty simple: if the bitmap is all zero, we don't need to do anything to
> clean it.
>
> Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
>
> diff -r 66566cf6b576 drivers/kvm/kvm_main.c
> --- a/drivers/kvm/kvm_main.c Fri Jul 27 16:27:11 2007 +1000
> +++ b/drivers/kvm/kvm_main.c Mon Jul 30 23:15:47 2007 +1000
> @@ -838,11 +838,13 @@ static int kvm_vm_ioctl_get_dirty_log(st
> if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
> goto out;
>
> - spin_lock(&kvm->lock);
> - kvm_mmu_slot_remove_write_access(kvm, log->slot);
> - kvm_flush_remote_tlbs(kvm);
> - memset(memslot->dirty_bitmap, 0, n);
> - spin_unlock(&kvm->lock);
> + if (any) {
> + spin_lock(&kvm->lock);
> + kvm_mmu_slot_remove_write_access(kvm, log->slot);
> + kvm_flush_remote_tlbs(kvm);
> + memset(memslot->dirty_bitmap, 0, n);
> + spin_unlock(&kvm->lock);
> + }
>
spin_lock()? my, that's so last week. kvm->lock is a mutex.
--
error compiling committee.c: too many arguments to function
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