From: Vipin Sharma <vipinsh@google.com>
Date: Mon, 2 May 2022 22:03:47 +0000 (+0000)
Subject: KVM: x86/mmu: Speed up slot_rmap_walk_next for sparsely populated rmaps
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=6ba1e04fa60787ced4c9049cf7bd6cd0f1b80764;p=linux.git

KVM: x86/mmu: Speed up slot_rmap_walk_next for sparsely populated rmaps

Avoid calling handlers on empty rmap entries and skip to the next non
empty rmap entry.

Empty rmap entries are noop in handlers.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220502220347.174664-1-vipinsh@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ea4bc085bbf5b..efe5a3dca1e09 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1483,9 +1483,11 @@ static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator)
 
 static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator)
 {
-	if (++iterator->rmap <= iterator->end_rmap) {
+	while (++iterator->rmap <= iterator->end_rmap) {
 		iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level));
-		return;
+
+		if (iterator->rmap->val)
+			return;
 	}
 
 	if (++iterator->level > iterator->end_level) {