2 files changed, 67 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/kvm_nested.h b/arch/arm64/include/asm/kvm_nested.h
index cce0e4cb5448..2be6c3de74e3 100644
--- a/arch/arm64/include/asm/kvm_nested.h
+++ b/arch/arm64/include/asm/kvm_nested.h
@@ -353,6 +353,8 @@ struct s1_walk_result {
 
 int __kvm_translate_va(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 		       struct s1_walk_result *wr, u64 va);
+int __kvm_find_s1_desc_level(struct kvm_vcpu *vcpu, u64 va, u64 ipa,
+			     int *level);
 
 /* VNCR management */
 int kvm_vcpu_allocate_vncr_tlb(struct kvm_vcpu *vcpu);
diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c
index b70b777a3c20..20bb9af125b1 100644
--- a/arch/arm64/kvm/at.c
+++ b/arch/arm64/kvm/at.c
@@ -1569,3 +1569,68 @@ int __kvm_translate_va(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
 
 	return 0;
 }
+
+struct desc_match {
+	u64	ipa;
+	int	level;
+};
+
+static int match_s1_desc(struct s1_walk_context *ctxt, void *priv)
+{
+	struct desc_match *dm = priv;
+	u64 ipa = dm->ipa;
+
+	/* Use S1 granule alignment */
+	ipa &= GENMASK(51, ctxt->wi->pgshift);
+
+	/* Not the IPA we're looking for? Continue. */
+	if (ipa != ctxt->table_ipa)
+		return 0;
+
+	/* Note the level and interrupt the walk */
+	dm->level = ctxt->level;
+	return -EINTR;
+}
+
+int __kvm_find_s1_desc_level(struct kvm_vcpu *vcpu, u64 va, u64 ipa, int *level)
+{
+	struct desc_match dm = {
+		.ipa	= ipa,
+	};
+	struct s1_walk_info wi = {
+		.filter	= &(struct s1_walk_filter){
+			.fn	= match_s1_desc,
+			.priv	= &dm,
+		},
+		.regime	= TR_EL10,
+		.as_el0	= false,
+		.pan	= false,
+	};
+	struct s1_walk_result wr = {};
+	int ret;
+
+	ret = setup_s1_walk(vcpu, &wi, &wr, va);
+	if (ret)
+		return ret;
+
+	/* We really expect the S1 MMU to be on here... */
+	if (WARN_ON_ONCE(wr.level == S1_MMU_DISABLED)) {
+		*level = 0;
+		return 0;
+	}
+
+	/* Walk the guest's PT, looking for a match along the way */
+	ret = walk_s1(vcpu, &wi, &wr, va);
+	switch (ret) {
+	case -EINTR:
+		/* We interrupted the walk on a match, return the level */
+		*level = dm.level;
+		return 0;
+	case 0:
+		/* The walk completed, we failed to find the entry */
+		return -ENOENT;
+	default:
+		/* Any other error... */
+		return ret;
+	}
+}