KVM: s390: gs support for kvm guests

This patch adds guarded storage support for KVM guest. We need to
setup the necessary control blocks, the kvm_run structure for the
new registers, the necessary wrappers for VSIE, as well as the
machine check save areas.
GS is enabled lazily and the register saving and reloading is done in
KVM code.  As this feature adds new content for migration, we provide
a new capability for enablement (KVM_CAP_S390_GS).

Signed-off-by: Fan Zhang <zhangfan@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 62 insertions, 0 deletions

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 976373c03138..f83f18b77f3d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -405,6 +405,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_S390_RI:
 		r = test_facility(64);
 		break;
+	case KVM_CAP_S390_GS:
+		r = test_facility(133);
+		break;
 	default:
 		r = 0;
 	}
@@ -541,6 +544,20 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 		VM_EVENT(kvm, 3, "ENABLE: CAP_S390_RI %s",
 			 r ? "(not available)" : "(success)");
 		break;
+	case KVM_CAP_S390_GS:
+		r = -EINVAL;
+		mutex_lock(&kvm->lock);
+		if (atomic_read(&kvm->online_vcpus)) {
+			r = -EBUSY;
+		} else if (test_facility(133)) {
+			set_kvm_facility(kvm->arch.model.fac_mask, 133);
+			set_kvm_facility(kvm->arch.model.fac_list, 133);
+			r = 0;
+		}
+		mutex_unlock(&kvm->lock);
+		VM_EVENT(kvm, 3, "ENABLE: CAP_S390_GS %s",
+			 r ? "(not available)" : "(success)");
+		break;
 	case KVM_CAP_S390_USER_STSI:
 		VM_EVENT(kvm, 3, "%s", "ENABLE: CAP_S390_USER_STSI");
 		kvm->arch.user_stsi = 1;
@@ -1749,6 +1766,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 	kvm_s390_set_prefix(vcpu, 0);
 	if (test_kvm_facility(vcpu->kvm, 64))
 		vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB;
+	if (test_kvm_facility(vcpu->kvm, 133))
+		vcpu->run->kvm_valid_regs |= KVM_SYNC_GSCB;
 	/* fprs can be synchronized via vrs, even if the guest has no vx. With
 	 * MACHINE_HAS_VX, (load|store)_fpu_regs() will work with vrs format.
 	 */
@@ -1993,6 +2012,8 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 		vcpu->arch.sie_block->eca |= ECA_VX;
 		vcpu->arch.sie_block->ecd |= ECD_HOSTREGMGMT;
 	}
+	vcpu->arch.sie_block->sdnxo = ((unsigned long) &vcpu->run->s.regs.sdnx)
+					| SDNXC;
 	vcpu->arch.sie_block->riccbd = (unsigned long) &vcpu->run->s.regs.riccb;
 	vcpu->arch.sie_block->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
 
@@ -2720,8 +2741,10 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
 static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 {
 	struct runtime_instr_cb *riccb;
+	struct gs_cb *gscb;
 
 	riccb = (struct runtime_instr_cb *) &kvm_run->s.regs.riccb;
+	gscb = (struct gs_cb *) &kvm_run->s.regs.gscb;
 	vcpu->arch.sie_block->gpsw.mask = kvm_run->psw_mask;
 	vcpu->arch.sie_block->gpsw.addr = kvm_run->psw_addr;
 	if (kvm_run->kvm_dirty_regs & KVM_SYNC_PREFIX)
@@ -2756,6 +2779,19 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		VCPU_EVENT(vcpu, 3, "%s", "ENABLE: RI (sync_regs)");
 		vcpu->arch.sie_block->ecb3 |= ECB3_RI;
 	}
+	/*
+	 * If userspace sets the gscb (e.g. after migration) to non-zero,
+	 * we should enable GS here instead of doing the lazy enablement.
+	 */
+	if ((kvm_run->kvm_dirty_regs & KVM_SYNC_GSCB) &&
+	    test_kvm_facility(vcpu->kvm, 133) &&
+	    gscb->gssm &&
+	    !vcpu->arch.gs_enabled) {
+		VCPU_EVENT(vcpu, 3, "%s", "ENABLE: GS (sync_regs)");
+		vcpu->arch.sie_block->ecb |= ECB_GS;
+		vcpu->arch.sie_block->ecd |= ECD_HOSTREGMGMT;
+		vcpu->arch.gs_enabled = 1;
+	}
 	save_access_regs(vcpu->arch.host_acrs);
 	restore_access_regs(vcpu->run->s.regs.acrs);
 	/* save host (userspace) fprs/vrs */
@@ -2770,6 +2806,20 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	if (test_fp_ctl(current->thread.fpu.fpc))
 		/* User space provided an invalid FPC, let's clear it */
 		current->thread.fpu.fpc = 0;
+	if (MACHINE_HAS_GS) {
+		preempt_disable();
+		__ctl_set_bit(2, 4);
+		if (current->thread.gs_cb) {
+			vcpu->arch.host_gscb = current->thread.gs_cb;
+			save_gs_cb(vcpu->arch.host_gscb);
+		}
+		if (vcpu->arch.gs_enabled) {
+			current->thread.gs_cb = (struct gs_cb *)
+						&vcpu->run->s.regs.gscb;
+			restore_gs_cb(current->thread.gs_cb);
+		}
+		preempt_enable();
+	}
 
 	kvm_run->kvm_dirty_regs = 0;
 }
@@ -2796,6 +2846,18 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	/* Restore will be done lazily at return */
 	current->thread.fpu.fpc = vcpu->arch.host_fpregs.fpc;
 	current->thread.fpu.regs = vcpu->arch.host_fpregs.regs;
+	if (MACHINE_HAS_GS) {
+		__ctl_set_bit(2, 4);
+		if (vcpu->arch.gs_enabled)
+			save_gs_cb(current->thread.gs_cb);
+		preempt_disable();
+		current->thread.gs_cb = vcpu->arch.host_gscb;
+		restore_gs_cb(vcpu->arch.host_gscb);
+		preempt_enable();
+		if (!vcpu->arch.host_gscb)
+			__ctl_clear_bit(2, 4);
+		vcpu->arch.host_gscb = NULL;
+	}
 
 }