[v2,15/28] KVM: x86/mmu: Skip no-op changes in TDP MMU functions
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Message ID 20210202185734.1680553-16-bgardon@google.com
State New, archived
Headers show
Series
  • Allow parallel MMU operations with TDP MMU
Related show

Commit Message

Ben Gardon Feb. 2, 2021, 6:57 p.m. UTC
Skip setting SPTEs if no change is expected.

Reviewed-by: Peter Feiner <pfeiner@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>

---

v1 -> v2
- Merged no-op checks into exiting old_spte check

 arch/x86/kvm/mmu/tdp_mmu.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Patch
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diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index c8a1149cb229..aeb05f626b55 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -888,7 +888,8 @@  static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 			continue;
 
 		if (!is_shadow_present_pte(iter.old_spte) ||
-		    !is_last_spte(iter.old_spte, iter.level))
+		    !is_last_spte(iter.old_spte, iter.level) ||
+		    !(iter.old_spte & PT_WRITABLE_MASK))
 			continue;
 
 		new_spte = iter.old_spte & ~PT_WRITABLE_MASK;
@@ -1065,7 +1066,8 @@  static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
 		if (tdp_mmu_iter_cond_resched(kvm, &iter, false))
 			continue;
 
-		if (!is_shadow_present_pte(iter.old_spte))
+		if (!is_shadow_present_pte(iter.old_spte) ||
+		    iter.old_spte & shadow_dirty_mask)
 			continue;
 
 		new_spte = iter.old_spte | shadow_dirty_mask;