lkml.org 
[lkml]   [2012]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/4] KVM: Avoid checking huge page mappings in get_dirty_log()
Marcelo Tosatti <mtosatti@redhat.com> wrote:

> guest fault enable dirty logging
>
> tdp_page_fault (all _page_fault functions) kvm_set_memory_region
>
>
> level = mapping_level(vcpu, gfn)
> (finds level == 2 or 3)
>
>
> rcu_assign_pointer(slot
> with
> ->dirty_bitmap)
> synchronize_srcu_expedited()

Isn't here still in the SRCU read-side critical section?

> schedule()
> kvm_arch_commit_memory_region()
> spin_lock(mmu_lock)
> kvm_mmu_slot_remove_write_access()
> removes large sptes
> spin_unlock(mmu_lock)
> spin_lock(mmu_lock)
> create large spte accordingly
> to level above
> spin_unlock(mmu_lock)
>

If so, we cannot start kvm_arch_commit_memory_region() until the completion
of the SRCU critical section and this race will not happen.

Takuya


\
 
 \ /
  Last update: 2012-03-14 06:31    [W:0.142 / U:0.044 seconds]
©2003-2014 Jasper Spaans. Advertise on this site