[PATCH 02/10] KVM: s390: add the GIB and its related life-cyle functions

[Michael Mueller <mimu@xxxxxxxxxxxxx>]

The GIB (Guest Information Block) links the GISA of all guests
that have adapter interrupts pending. These interrupts cannot be
deliverd because no vcpu of these guests is currently running in
SIE context. Instead, a GIB alert is issued on the host to schedule
these guests to run.

This mechanism allows to process adapter interrupts for currently
not running guests.

The GIB is created during host initialization and associated with
the Adapter Interruption Facility in case an Adapter Interruption
Virtualization Facility is available.

Signed-off-by: Michael Mueller <mimu@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/kvm_host.h | 10 ++++++++
 arch/s390/kvm/interrupt.c        | 43 ++++++++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.c         |  1 +
 arch/s390/kvm/kvm-s390.h         |  2 ++
 4 files changed, 56 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 29c940bf8506..01be3b666b11 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -776,6 +776,15 @@ struct kvm_s390_gisa {
 	};
 };
 
+struct kvm_s390_gib {
+	atomic_t alert_list_origin;
+	u32 reserved01;
+	u8:5;
+	u8  nisc:3;
+	u8  reserved03[3];
+	u32 reserved04[5];
+};
+
 /*
  * sie_page2 has to be allocated as DMA because fac_list, crycb and
  * gisa need 31bit addresses in the sie control block.
@@ -829,6 +838,7 @@ struct kvm_arch{
 	/* subset of available cpu features enabled by user space */
 	DECLARE_BITMAP(cpu_feat, KVM_S390_VM_CPU_FEAT_NR_BITS);
 	struct kvm_s390_gisa *gisa;
+	int gib_in_use;
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index fcb55b02990e..3789a9ad8dee 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -31,6 +31,8 @@
 #define PFAULT_DONE 0x0680
 #define VIRTIO_PARAM 0x0d00
 
+static struct kvm_s390_gib *gib;
+
 /* handle external calls via sigp interpretation facility */
 static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)
 {
@@ -2899,6 +2901,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 		kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
 		VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
 		kvm_s390_gisa_clear(kvm);
+		kvm->arch.gib_in_use = !!gib;
 	}
 }
 
@@ -2908,3 +2911,43 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
 		return;
 	kvm->arch.gisa = NULL;
 }
+
+void kvm_s390_gib_destroy(void)
+{
+	if (!gib)
+		return;
+	chsc_sgib(0);
+	free_page((unsigned long)gib);
+	gib = NULL;
+}
+
+void kvm_s390_gib_init(u8 nisc)
+{
+	int rc;
+
+	if (gib)
+		return;
+
+	if (!css_general_characteristics.aiv) {
+		KVM_EVENT(3, "%s", "gib not initialized, no AIV facility");
+		return;
+	}
+
+	gib = (struct kvm_s390_gib *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!gib) {
+		KVM_EVENT(3, "%s", "gib memory allocation failed");
+		return;
+	}
+
+	gib->nisc = nisc;
+	rc = chsc_sgib((u32)(u64)gib);
+	if (rc) {
+		KVM_EVENT(3, "gib 0x%pK AIV association failed rc: %d",
+			  gib, rc);
+		free_page((unsigned long)gib);
+		gib = NULL;
+		return;
+	}
+
+	KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
+}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index ac5da6b0b862..c75b01856092 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -433,6 +433,7 @@ int kvm_arch_init(void *opaque)
 
 void kvm_arch_exit(void)
 {
+	kvm_s390_gib_destroy();
 	debug_unregister(kvm_s390_dbf);
 }
 
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 981e3ba97461..5983800d6433 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -380,6 +380,8 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu,
 void kvm_s390_gisa_init(struct kvm *kvm);
 void kvm_s390_gisa_clear(struct kvm *kvm);
 void kvm_s390_gisa_destroy(struct kvm *kvm);
+void kvm_s390_gib_init(u8 nisc);
+void kvm_s390_gib_destroy(void);
 
 /* implemented in guestdbg.c */
 void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu);
-- 
2.17.0