[PATCH RFC v2 03/11] KVM: s390: Move scao validation into a function

[Christoph Schlameuss <schlameuss@linux.ibm.com>]

This improves readability as well as allows re-use in coming patches.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index ced2ca4ce5b584403d900ed11cb064919feda8e9..3d602bbd1f70b7bd8ddc2c54d43027dc37a6e032 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -95,6 +95,25 @@ static int set_validity_icpt(struct kvm_s390_sie_block *scb,
 	return 1;
 }
 
+/* The sca header must not cross pages etc. */
+static int validate_scao(struct kvm_vcpu *vcpu, struct kvm_s390_sie_block *scb, gpa_t gpa)
+{
+	int offset;
+
+	if (gpa < 2 * PAGE_SIZE)
+		return set_validity_icpt(scb, 0x0038U);
+	if ((gpa & ~0x1fffUL) == kvm_s390_get_prefix(vcpu))
+		return set_validity_icpt(scb, 0x0011U);
+
+	if (sie_uses_esca(scb))
+		offset = offsetof(struct esca_block, cpu[0]) - 1;
+	else
+		offset = offsetof(struct bsca_block, cpu[0]) - 1;
+	if ((gpa & PAGE_MASK) != ((gpa + offset) & PAGE_MASK))
+		return set_validity_icpt(scb, 0x003bU);
+	return false;
+}
+
 /* mark the prefix as unmapped, this will block the VSIE */
 static void prefix_unmapped(struct vsie_page *vsie_page)
 {
@@ -791,13 +810,7 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 
 	gpa = read_scao(vcpu->kvm, scb_o);
 	if (gpa) {
-		if (gpa < 2 * PAGE_SIZE)
-			rc = set_validity_icpt(scb_s, 0x0038U);
-		else if ((gpa & ~0x1fffUL) == kvm_s390_get_prefix(vcpu))
-			rc = set_validity_icpt(scb_s, 0x0011U);
-		else if ((gpa & PAGE_MASK) !=
-			 ((gpa + sizeof(struct bsca_block) - 1) & PAGE_MASK))
-			rc = set_validity_icpt(scb_s, 0x003bU);
+		rc = validate_scao(vcpu, scb_o, gpa);
 		if (!rc) {
 			rc = pin_guest_page(vcpu->kvm, gpa, &hpa);
 			if (rc)

-- 
2.51.1