[PATCH v4 2/4] s390: uv: UV feature check utility

[Steffen Eiden <seiden@linux.ibm.com>]

Introduces a function to check the existence of an UV feature.
Refactor feature bit checks to use the new function.

Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
---
 arch/s390/include/asm/uv.h | 7 +++++++
 arch/s390/kernel/uv.c      | 2 +-
 arch/s390/kvm/kvm-s390.c   | 2 +-
 arch/s390/mm/fault.c       | 2 +-
 4 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index d2cd42bb2c26..823adfff7315 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -397,6 +397,13 @@ struct uv_info {
 
 extern struct uv_info uv_info;
 
+static inline bool uv_has_feature(u8 feature_bit)
+{
+	if (feature_bit >= sizeof(uv_info.uv_feature_indications) * 8)
+		return false;
+	return test_bit_inv(feature_bit, &uv_info.uv_feature_indications);
+}
+
 #ifdef CONFIG_PROTECTED_VIRTUALIZATION_GUEST
 extern int prot_virt_guest;
 
diff --git a/arch/s390/kernel/uv.c b/arch/s390/kernel/uv.c
index b771f1b4cdd1..fc07bc39e698 100644
--- a/arch/s390/kernel/uv.c
+++ b/arch/s390/kernel/uv.c
@@ -258,7 +258,7 @@ static bool should_export_before_import(struct uv_cb_header *uvcb, struct mm_str
 	 * shared page from a different protected VM will automatically also
 	 * transfer its ownership.
 	 */
-	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications))
+	if (uv_has_feature(BIT_UV_FEAT_MISC))
 		return false;
 	if (uvcb->cmd == UVC_CMD_UNPIN_PAGE_SHARED)
 		return false;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e6511608280c..813cc3d59c90 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2406,7 +2406,7 @@ static int kvm_s390_cpus_to_pv(struct kvm *kvm, u16 *rc, u16 *rrc)
 	struct kvm_vcpu *vcpu;
 
 	/* Disable the GISA if the ultravisor does not support AIV. */
-	if (!test_bit_inv(BIT_UV_FEAT_AIV, &uv_info.uv_feature_indications))
+	if (!uv_has_feature(BIT_UV_FEAT_AIV))
 		kvm_s390_gisa_disable(kvm);
 
 	kvm_for_each_vcpu(i, vcpu, kvm) {
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index b5e1bea9194c..8a86dd725870 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -599,7 +599,7 @@ void do_secure_storage_access(struct pt_regs *regs)
 	 * reliable without the misc UV feature so we need to check
 	 * for that as well.
 	 */
-	if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
+	if (uv_has_feature(BIT_UV_FEAT_MISC) &&
 	    !test_bit_inv(61, &regs->int_parm_long)) {
 		/*
 		 * When this happens, userspace did something that it
-- 
2.41.0