kvm: x86/mmu: Support changed pte notifier in tdp MMU

In order to interoperate correctly with the rest of KVM and other Linux
subsystems, the TDP MMU must correctly handle various MMU notifiers. Add
a hook and handle the change_pte MMU notifier.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
	https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201014182700.2888246-15-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index dd6b8a8f1c93..64e640cfcff9 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -671,3 +671,59 @@ int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva)
 	return kvm_tdp_mmu_handle_hva_range(kvm, hva, hva + 1, 0,
 					    test_age_gfn);
 }
+
+/*
+ * Handle the changed_pte MMU notifier for the TDP MMU.
+ * data is a pointer to the new pte_t mapping the HVA specified by the MMU
+ * notifier.
+ * Returns non-zero if a flush is needed before releasing the MMU lock.
+ */
+static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot,
+			struct kvm_mmu_page *root, gfn_t gfn, gfn_t unused,
+			unsigned long data)
+{
+	struct tdp_iter iter;
+	pte_t *ptep = (pte_t *)data;
+	kvm_pfn_t new_pfn;
+	u64 new_spte;
+	int need_flush = 0;
+
+	WARN_ON(pte_huge(*ptep));
+
+	new_pfn = pte_pfn(*ptep);
+
+	tdp_root_for_each_pte(iter, root, gfn, gfn + 1) {
+		if (iter.level != PG_LEVEL_4K)
+			continue;
+
+		if (!is_shadow_present_pte(iter.old_spte))
+			break;
+
+		tdp_mmu_set_spte(kvm, &iter, 0);
+
+		kvm_flush_remote_tlbs_with_address(kvm, iter.gfn, 1);
+
+		if (!pte_write(*ptep)) {
+			new_spte = kvm_mmu_changed_pte_notifier_make_spte(
+					iter.old_spte, new_pfn);
+
+			tdp_mmu_set_spte(kvm, &iter, new_spte);
+		}
+
+		need_flush = 1;
+	}
+
+	if (need_flush)
+		kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
+
+	return 0;
+}
+
+int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address,
+			     pte_t *host_ptep)
+{
+	return kvm_tdp_mmu_handle_hva_range(kvm, address, address + 1,
+					    (unsigned long)host_ptep,
+					    set_tdp_spte);
+}
+