[PATCH] KVM: s390: vsie: fix crycb virtual vs physical usage

[Pierre Morel <pmorel@linux.ibm.com>]

Prepare VSIE for architectural changes where lowmem kernel real and
kernel virtual address are different.

When we get the original crycb from the guest crycb we can use the
phys_to_virt transformation, which will use the host transformations,
but we must use an offset to calculate the guest real address apcb
and give it to read_guest_real().

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 37 ++++++++++++++++++++++---------------
 1 file changed, 22 insertions(+), 15 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 94138f8f0c1c..f37851c9b1ab 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -138,9 +138,12 @@ static int prepare_cpuflags(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 }
 /* Copy to APCB FORMAT1 from APCB FORMAT0 */
 static int setup_apcb10(struct kvm_vcpu *vcpu, struct kvm_s390_apcb1 *apcb_s,
-			unsigned long apcb_o, struct kvm_s390_apcb1 *apcb_h)
+			unsigned long crycb_o, struct kvm_s390_apcb1 *apcb_h)
 {
 	struct kvm_s390_apcb0 tmp;
+	unsigned long apcb_o;
+
+	apcb_o = crycb_o + offsetof(struct kvm_s390_crypto_cb, apcb0);
 
 	if (read_guest_real(vcpu, apcb_o, &tmp, sizeof(struct kvm_s390_apcb0)))
 		return -EFAULT;
@@ -157,14 +160,18 @@ static int setup_apcb10(struct kvm_vcpu *vcpu, struct kvm_s390_apcb1 *apcb_s,
  * setup_apcb00 - Copy to APCB FORMAT0 from APCB FORMAT0
  * @vcpu: pointer to the virtual CPU
  * @apcb_s: pointer to start of apcb in the shadow crycb
- * @apcb_o: pointer to start of original apcb in the guest2
+ * @crycb_o: real guest address to start of original guest crycb
  * @apcb_h: pointer to start of apcb in the guest1
  *
  * Returns 0 and -EFAULT on error reading guest apcb
  */
 static int setup_apcb00(struct kvm_vcpu *vcpu, unsigned long *apcb_s,
-			unsigned long apcb_o, unsigned long *apcb_h)
+			unsigned long crycb_o, unsigned long *apcb_h)
 {
+	unsigned long apcb_o;
+
+	apcb_o = crycb_o + offsetof(struct kvm_s390_crypto_cb, apcb0);
+
 	if (read_guest_real(vcpu, apcb_o, apcb_s,
 			    sizeof(struct kvm_s390_apcb0)))
 		return -EFAULT;
@@ -178,15 +185,19 @@ static int setup_apcb00(struct kvm_vcpu *vcpu, unsigned long *apcb_s,
  * setup_apcb11 - Copy the FORMAT1 APCB from the guest to the shadow CRYCB
  * @vcpu: pointer to the virtual CPU
  * @apcb_s: pointer to start of apcb in the shadow crycb
- * @apcb_o: pointer to start of original guest apcb
+ * @crycb_o: real guest address to start of original guest crycb
  * @apcb_h: pointer to start of apcb in the host
  *
  * Returns 0 and -EFAULT on error reading guest apcb
  */
 static int setup_apcb11(struct kvm_vcpu *vcpu, unsigned long *apcb_s,
-			unsigned long apcb_o,
+			unsigned long crycb_o,
 			unsigned long *apcb_h)
 {
+	unsigned long apcb_o;
+
+	apcb_o = crycb_o + offsetof(struct kvm_s390_crypto_cb, apcb1);
+
 	if (read_guest_real(vcpu, apcb_o, apcb_s,
 			    sizeof(struct kvm_s390_apcb1)))
 		return -EFAULT;
@@ -200,7 +211,7 @@ static int setup_apcb11(struct kvm_vcpu *vcpu, unsigned long *apcb_s,
  * setup_apcb - Create a shadow copy of the apcb.
  * @vcpu: pointer to the virtual CPU
  * @crycb_s: pointer to shadow crycb
- * @crycb_o: pointer to original guest crycb
+ * @crycb_o: real address of original guest crycb
  * @crycb_h: pointer to the host crycb
  * @fmt_o: format of the original guest crycb.
  * @fmt_h: format of the host crycb.
@@ -215,10 +226,6 @@ static int setup_apcb(struct kvm_vcpu *vcpu, struct kvm_s390_crypto_cb *crycb_s,
 	       struct kvm_s390_crypto_cb *crycb_h,
 	       int fmt_o, int fmt_h)
 {
-	struct kvm_s390_crypto_cb *crycb;
-
-	crycb = (struct kvm_s390_crypto_cb *) (unsigned long)crycb_o;
-
 	switch (fmt_o) {
 	case CRYCB_FORMAT2:
 		if ((crycb_o & PAGE_MASK) != ((crycb_o + 256) & PAGE_MASK))
@@ -226,18 +233,18 @@ static int setup_apcb(struct kvm_vcpu *vcpu, struct kvm_s390_crypto_cb *crycb_s,
 		if (fmt_h != CRYCB_FORMAT2)
 			return -EINVAL;
 		return setup_apcb11(vcpu, (unsigned long *)&crycb_s->apcb1,
-				    (unsigned long) &crycb->apcb1,
+				    crycb_o,
 				    (unsigned long *)&crycb_h->apcb1);
 	case CRYCB_FORMAT1:
 		switch (fmt_h) {
 		case CRYCB_FORMAT2:
 			return setup_apcb10(vcpu, &crycb_s->apcb1,
-					    (unsigned long) &crycb->apcb0,
+					    crycb_o,
 					    &crycb_h->apcb1);
 		case CRYCB_FORMAT1:
 			return setup_apcb00(vcpu,
 					    (unsigned long *) &crycb_s->apcb0,
-					    (unsigned long) &crycb->apcb0,
+					    crycb_o,
 					    (unsigned long *) &crycb_h->apcb0);
 		}
 		break;
@@ -248,13 +255,13 @@ static int setup_apcb(struct kvm_vcpu *vcpu, struct kvm_s390_crypto_cb *crycb_s,
 		switch (fmt_h) {
 		case CRYCB_FORMAT2:
 			return setup_apcb10(vcpu, &crycb_s->apcb1,
-					    (unsigned long) &crycb->apcb0,
+					    crycb_o,
 					    &crycb_h->apcb1);
 		case CRYCB_FORMAT1:
 		case CRYCB_FORMAT0:
 			return setup_apcb00(vcpu,
 					    (unsigned long *) &crycb_s->apcb0,
-					    (unsigned long) &crycb->apcb0,
+					    crycb_o,
 					    (unsigned long *) &crycb_h->apcb0);
 		}
 	}
-- 
2.31.1