[PATCH RFC v2 01/11] KVM: s390: Add SCAO read and write helpers

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

Introduce some small helper functions to get and set the system control
area origin address from the SIE control block.

Signed-off-by: Christoph Schlameuss <schlameuss@linux.ibm.com>
---
 arch/s390/kvm/vsie.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 347268f89f2f186bea623a3adff7376cabc305b2..ced2ca4ce5b584403d900ed11cb064919feda8e9 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -123,6 +123,23 @@ static int prefix_is_mapped(struct vsie_page *vsie_page)
 	return !(atomic_read(&vsie_page->scb_s.prog20) & PROG_REQUEST);
 }
 
+static gpa_t read_scao(struct kvm *kvm, struct kvm_s390_sie_block *scb)
+{
+	gpa_t sca;
+
+	sca = READ_ONCE(scb->scaol) & ~0xfUL;
+	if (test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_64BSCAO))
+		sca |= (u64)READ_ONCE(scb->scaoh) << 32;
+
+	return sca;
+}
+
+static void write_scao(struct kvm_s390_sie_block *scb, hpa_t hpa)
+{
+	scb->scaoh = (u32)((u64)hpa >> 32);
+	scb->scaol = (u32)(u64)hpa;
+}
+
 /* copy the updated intervention request bits into the shadow scb */
 static void update_intervention_requests(struct vsie_page *vsie_page)
 {
@@ -714,12 +731,11 @@ static void unpin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
 	hpa_t hpa;
 
-	hpa = (u64) scb_s->scaoh << 32 | scb_s->scaol;
+	hpa = read_scao(vcpu->kvm, scb_s);
 	if (hpa) {
 		unpin_guest_page(vcpu->kvm, vsie_page->sca_gpa, hpa);
 		vsie_page->sca_gpa = 0;
-		scb_s->scaol = 0;
-		scb_s->scaoh = 0;
+		write_scao(scb_s, 0);
 	}
 
 	hpa = scb_s->itdba;
@@ -773,9 +789,7 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	gpa_t gpa;
 	int rc = 0;
 
-	gpa = READ_ONCE(scb_o->scaol) & ~0xfUL;
-	if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_64BSCAO))
-		gpa |= (u64) READ_ONCE(scb_o->scaoh) << 32;
+	gpa = read_scao(vcpu->kvm, scb_o);
 	if (gpa) {
 		if (gpa < 2 * PAGE_SIZE)
 			rc = set_validity_icpt(scb_s, 0x0038U);
@@ -792,8 +806,7 @@ static int pin_blocks(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 		if (rc)
 			goto unpin;
 		vsie_page->sca_gpa = gpa;
-		scb_s->scaoh = (u32)((u64)hpa >> 32);
-		scb_s->scaol = (u32)(u64)hpa;
+		write_scao(scb_s, hpa);
 	}
 
 	gpa = READ_ONCE(scb_o->itdba) & ~0xffUL;

-- 
2.51.1