Set the min_level for the TDP iterator at the root level when zapping all
SPTEs so that the _iterator_ only processes top-level SPTEs. Zapping a
non-leaf SPTE will recursively zap all its children, thus there is no
need for the iterator to attempt to step down. This avoids rereading all
the top-level SPTEs after they are zapped by causing try_step_down() to
short-circuit.
Cc: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6566f70a31c1..aec069c18d82 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -751,6 +751,16 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
{
bool zap_all = (end == ZAP_ALL_END);
struct tdp_iter iter;
+ int min_level;
+
+ /*
+ * No need to step down in the iterator when zapping all SPTEs, zapping
+ * the top-level non-leaf SPTEs will recurse on all their children.
+ */
+ if (zap_all)
+ min_level = root->role.level;
+ else
+ min_level = PG_LEVEL_4K;
/*
* Bound the walk at host.MAXPHYADDR, guest accesses beyond that will
@@ -763,7 +773,8 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
rcu_read_lock();
- tdp_root_for_each_pte(iter, root, start, end) {
+ for_each_tdp_pte_min_level(iter, root->spt, root->role.level,
+ min_level, start, end) {
retry:
if (can_yield &&
tdp_mmu_iter_cond_resched(kvm, &iter, flush, shared)) {
--
2.33.0.rc1.237.g0d66db33f3-goog
