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Commit 9a3aad70 authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
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KVM: MMU: using __xchg_spte more smarter 



Sometimes, atomically set spte is not needed, this patch call __xchg_spte()
more smartly

Note: if the old mapping's access bit is already set, we no need atomic operation
since the access bit is not lost

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent e4b502ea

arch/x86/kvm/mmu.c

+7 −2
Original line number Diff line number Diff line
@@ -682,9 +682,14 @@ static void rmap_remove(struct kvm *kvm, u64 *spte) 
static void set_spte_track_bits(u64 *sptep, u64 new_spte)

{

	pfn_t pfn;

	u64 old_spte;

	u64 old_spte = *sptep;



	if (!shadow_accessed_mask || !is_shadow_present_pte(old_spte) ||

	      old_spte & shadow_accessed_mask) {

		__set_spte(sptep, new_spte);

	} else

		old_spte = __xchg_spte(sptep, new_spte);



	if (!is_rmap_spte(old_spte))

		return;

	pfn = spte_to_pfn(old_spte);