Peter,
On Sat, Apr 11, 2009 at 12:45:21AM -0400, Peter Teoh wrote:
> In this function, the TLB flushing comes before spin unlock,
>
> void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
> {
> struct kvm_mmu_page *sp;
>
> spin_lock(&kvm->mmu_lock);
>
> kvm_flush_remote_tlbs(kvm);
> spin_unlock(&kvm->mmu_lock);
> }
kvm_vm_ioctl_get_dirty_log does:
down_write(slots_lock)
- collect data from dirty bitmap (kvm_get_dirty_log)
if (something was dirty)
- remove write access for all translations
- flush remote tlb's
- clear the dirty bitmap
up_write(slots_lock)
The vmexit path (take a look at vcpu_run), takes slots_lock in
read-mode. This means that no other vcpu will be able to dirty a
shadow translation (spte) in the meantime.
So its safe.
> but in kvm_vm_ioctl_set_memory_alias():
>
> spin_unlock(&kvm->mmu_lock);
> kvm_mmu_zap_all(kvm);
>
> it comes after inside kvm_mmu_zap_all(). Does it sound logical?
Note that here it also takes slots_lock in write-mode, which blocks all
other vcpus.
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