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| author | Xiao Guangrong <xiaoguangrong@cn.fujitsu.com> | 2010-07-16 11:30:18 +0800 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-08-02 06:41:01 +0300 |
| commit | 9a3aad70572c3f4d55e7f09ac4eb313d41d0a484 (patch) | |
| tree | f3c1efd08eed5b0f37078c9b91658e25e7775808 /arch | |
| parent | e4b502ead259fcf70839414abb7c8cdc3b523f01 (diff) | |
| download | lwn-9a3aad70572c3f4d55e7f09ac4eb313d41d0a484.tar.gz lwn-9a3aad70572c3f4d55e7f09ac4eb313d41d0a484.zip | |
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: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/mmu.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index e4b862eb8885..0dcc95e09876 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -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); - old_spte = __xchg_spte(sptep, new_spte); if (!is_rmap_spte(old_spte)) return; pfn = spte_to_pfn(old_spte); |