1 files changed, 48 insertions, 5 deletions

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 9816b0060fbe..21c2e61fece4 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -18,6 +18,8 @@
 #include "kvm-s390.h"
 #include "gaccess.h"
 
+#define GMAP_SHADOW_FAKE_TABLE 1ULL
+
 /*
  * vaddress union in order to easily decode a virtual address into its
  * region first index, region second index etc. parts.
@@ -317,7 +319,7 @@ enum prot_type {
 	PROT_TYPE_DAT  = 3,
 	PROT_TYPE_IEP  = 4,
 	/* Dummy value for passing an initialized value when code != PGM_PROTECTION */
-	PROT_NONE,
+	PROT_TYPE_DUMMY,
 };
 
 static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva, u8 ar,
@@ -333,7 +335,7 @@ static int trans_exc_ending(struct kvm_vcpu *vcpu, int code, unsigned long gva,
 	switch (code) {
 	case PGM_PROTECTION:
 		switch (prot) {
-		case PROT_NONE:
+		case PROT_TYPE_DUMMY:
 			/* We should never get here, acts like termination */
 			WARN_ON_ONCE(1);
 			break;
@@ -803,7 +805,7 @@ static int guest_range_to_gpas(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 			gpa = kvm_s390_real_to_abs(vcpu, ga);
 			if (!kvm_is_gpa_in_memslot(vcpu->kvm, gpa)) {
 				rc = PGM_ADDRESSING;
-				prot = PROT_NONE;
+				prot = PROT_TYPE_DUMMY;
 			}
 		}
 		if (rc)
@@ -961,7 +963,7 @@ int access_guest_with_key(struct kvm_vcpu *vcpu, unsigned long ga, u8 ar,
 		if (rc == PGM_PROTECTION)
 			prot = PROT_TYPE_KEYC;
 		else
-			prot = PROT_NONE;
+			prot = PROT_TYPE_DUMMY;
 		rc = trans_exc_ending(vcpu, rc, ga, ar, mode, prot, terminate);
 	}
 out_unlock:
@@ -1393,6 +1395,44 @@ shadow_pgt:
 }
 
 /**
+ * shadow_pgt_lookup() - find a shadow page table
+ * @sg: pointer to the shadow guest address space structure
+ * @saddr: the address in the shadow aguest address space
+ * @pgt: parent gmap address of the page table to get shadowed
+ * @dat_protection: if the pgtable is marked as protected by dat
+ * @fake: pgt references contiguous guest memory block, not a pgtable
+ *
+ * Returns 0 if the shadow page table was found and -EAGAIN if the page
+ * table was not found.
+ *
+ * Called with sg->mm->mmap_lock in read.
+ */
+static int shadow_pgt_lookup(struct gmap *sg, unsigned long saddr, unsigned long *pgt,
+			     int *dat_protection, int *fake)
+{
+	unsigned long pt_index;
+	unsigned long *table;
+	struct page *page;
+	int rc;
+
+	spin_lock(&sg->guest_table_lock);
+	table = gmap_table_walk(sg, saddr, 1); /* get segment pointer */
+	if (table && !(*table & _SEGMENT_ENTRY_INVALID)) {
+		/* Shadow page tables are full pages (pte+pgste) */
+		page = pfn_to_page(*table >> PAGE_SHIFT);
+		pt_index = gmap_pgste_get_pgt_addr(page_to_virt(page));
+		*pgt = pt_index & ~GMAP_SHADOW_FAKE_TABLE;
+		*dat_protection = !!(*table & _SEGMENT_ENTRY_PROTECT);
+		*fake = !!(pt_index & GMAP_SHADOW_FAKE_TABLE);
+		rc = 0;
+	} else  {
+		rc = -EAGAIN;
+	}
+	spin_unlock(&sg->guest_table_lock);
+	return rc;
+}
+
+/**
  * kvm_s390_shadow_fault - handle fault on a shadow page table
  * @vcpu: virtual cpu
  * @sg: pointer to the shadow guest address space structure
@@ -1415,6 +1455,9 @@ int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg,
 	int dat_protection, fake;
 	int rc;
 
+	if (KVM_BUG_ON(!gmap_is_shadow(sg), vcpu->kvm))
+		return -EFAULT;
+
 	mmap_read_lock(sg->mm);
 	/*
 	 * We don't want any guest-2 tables to change - so the parent
@@ -1423,7 +1466,7 @@ int kvm_s390_shadow_fault(struct kvm_vcpu *vcpu, struct gmap *sg,
 	 */
 	ipte_lock(vcpu->kvm);
 
-	rc = gmap_shadow_pgt_lookup(sg, saddr, &pgt, &dat_protection, &fake);
+	rc = shadow_pgt_lookup(sg, saddr, &pgt, &dat_protection, &fake);
 	if (rc)
 		rc = kvm_s390_shadow_tables(sg, saddr, &pgt, &dat_protection,
 					    &fake);