Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Michael Mueller <mimu@linux.ibm.com>
To:     kvm@vger.kernel.org
Cc:     cohuck@redhat.com, borntraeger@de.ibm.com, frankja@linux.ibm.com,
        thuth@redhat.com, pasic@linux.ibm.com, david@redhat.com,
        linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
        Michael Mueller <mimu@linux.ibm.com>
Subject: [PATCH] KVM: s390: pv: make use of ultravisor AIV support
Date:   Fri,  4 Feb 2022 09:52:03 +0100
Message-Id: <20220204085203.3490425-1-mimu@linux.ibm.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

This patch enables the ultravisor adapter interruption vitualization
support indicated by UV feature BIT_UV_FEAT_AIV. This allows ISC
interruption injection directly into the GISA IPM for PV kvm guests.

Hardware that does not support this feature will continue to use the
UV interruption interception method to deliver ISC interruptions to
PV kvm guests. For this purpose, the ECA_AIV bit for all guest cpus
will be cleared and the GISA will be disabled during PV guest setup.

In addition a check in __inject_io() has been removed. That reduces the
required intructions for interruption handling for PV and traditional
kvm guests.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
---
 arch/s390/include/asm/uv.h |  1 +
 arch/s390/kvm/interrupt.c  | 53 +++++++++++++++++++++++++++++++++-----
 arch/s390/kvm/kvm-s390.c   | 10 ++++---
 arch/s390/kvm/kvm-s390.h   | 11 ++++++++
 4 files changed, 66 insertions(+), 9 deletions(-)

diff --git a/arch/s390/include/asm/uv.h b/arch/s390/include/asm/uv.h
index 72d3e49c2860..0cb2bbb50ad7 100644
--- a/arch/s390/include/asm/uv.h
+++ b/arch/s390/include/asm/uv.h
@@ -80,6 +80,7 @@ enum uv_cmds_inst {
 
 enum uv_feat_ind {
 	BIT_UV_FEAT_MISC = 0,
+	BIT_UV_FEAT_AIV = 1,
 };
 
 struct uv_cb_header {
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index c3bd993fdd0c..6ff80069b1fe 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -1900,13 +1900,12 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 	isc = int_word_to_isc(inti->io.io_int_word);
 
 	/*
-	 * Do not make use of gisa in protected mode. We do not use the lock
-	 * checking variant as this is just a performance optimization and we
-	 * do not hold the lock here. This is ok as the code will pick
-	 * interrupts from both "lists" for delivery.
+	 * We do not use the lock checking variant as this is just a
+	 * performance optimization and we do not hold the lock here.
+	 * This is ok as the code will pick interrupts from both "lists"
+	 * for delivery.
 	 */
-	if (!kvm_s390_pv_get_handle(kvm) &&
-	    gi->origin && inti->type & KVM_S390_INT_IO_AI_MASK) {
+	if (gi->origin && inti->type & KVM_S390_INT_IO_AI_MASK) {
 		VM_EVENT(kvm, 4, "%s isc %1u", "inject: I/O (AI/gisa)", isc);
 		gisa_set_ipm_gisc(gi->origin, isc);
 		kfree(inti);
@@ -3163,9 +3162,32 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }
 
+void kvm_s390_gisa_enable(struct kvm *kvm)
+{
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	if (gi->origin)
+		return;
+	kvm_s390_gisa_init(kvm);
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		mutex_lock(&vcpu->mutex);
+		vcpu->arch.sie_block->gd = kvm_s390_get_gisa_desc(kvm);
+		if (vcpu->arch.sie_block->gd) {
+			vcpu->arch.sie_block->eca |= ECA_AIV;
+			VCPU_EVENT(vcpu, 3, "AIV gisa format-%u enabled for cpu %03u",
+				   vcpu->arch.sie_block->gd & 0x3, vcpu->vcpu_id);
+		}
+		mutex_unlock(&vcpu->mutex);
+	}
+}
+
+
 void kvm_s390_gisa_destroy(struct kvm *kvm)
 {
 	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+	struct kvm_s390_gisa *gisa = gi->origin;
 
 	if (!gi->origin)
 		return;
@@ -3176,6 +3198,25 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
 		cpu_relax();
 	hrtimer_cancel(&gi->timer);
 	gi->origin = NULL;
+	VM_EVENT(kvm, 3, "gisa 0x%pK destroyed", gisa);
+}
+
+void kvm_s390_gisa_disable(struct kvm *kvm)
+{
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	if (!gi->origin)
+		return;
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		mutex_lock(&vcpu->mutex);
+		vcpu->arch.sie_block->eca &= ~ECA_AIV;
+		vcpu->arch.sie_block->gd = 0U;
+		mutex_unlock(&vcpu->mutex);
+		VCPU_EVENT(vcpu, 3, "AIV disabled for cpu %03u", vcpu->vcpu_id);
+	}
+	kvm_s390_gisa_destroy(kvm);
 }
 
 /**
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 14a18ba5ff2c..8839a58e03c7 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2273,6 +2273,9 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 		if (r)
 			break;
 
+		if (!test_bit_inv(BIT_UV_FEAT_AIV, &uv_info.uv_feature_indications))
+			kvm_s390_gisa_disable(kvm);
+
 		r = kvm_s390_pv_init_vm(kvm, &cmd->rc, &cmd->rrc);
 		if (r)
 			break;
@@ -2300,6 +2303,9 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd)
 			break;
 		r = kvm_s390_pv_deinit_vm(kvm, &cmd->rc, &cmd->rrc);
 
+		if (use_gisa)
+			kvm_s390_gisa_enable(kvm);
+
 		/* no need to block service interrupts any more */
 		clear_bit(IRQ_PEND_EXT_SERVICE, &kvm->arch.float_int.masked_irqs);
 		break;
@@ -3309,9 +3315,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 
 	vcpu->arch.sie_block->icpua = vcpu->vcpu_id;
 	spin_lock_init(&vcpu->arch.local_int.lock);
-	vcpu->arch.sie_block->gd = (u32)(u64)vcpu->kvm->arch.gisa_int.origin;
-	if (vcpu->arch.sie_block->gd && sclp.has_gisaf)
-		vcpu->arch.sie_block->gd |= GISA_FORMAT1;
+	vcpu->arch.sie_block->gd = kvm_s390_get_gisa_desc(vcpu->kvm);
 	seqcount_init(&vcpu->arch.cputm_seqcount);
 
 	vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index c07a050d757d..08a622a44f6f 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -217,6 +217,15 @@ static inline void kvm_s390_set_user_cpu_state_ctrl(struct kvm *kvm)
 	kvm->arch.user_cpu_state_ctrl = 1;
 }
 
+static inline u32 kvm_s390_get_gisa_desc(struct kvm *kvm)
+{
+	u32 gd = (u32)(u64)kvm->arch.gisa_int.origin;
+
+	if (gd && sclp.has_gisaf)
+		gd |= GISA_FORMAT1;
+	return gd;
+}
+
 /* implemented in pv.c */
 int kvm_s390_pv_destroy_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
 int kvm_s390_pv_create_cpu(struct kvm_vcpu *vcpu, u16 *rc, u16 *rrc);
@@ -435,6 +444,8 @@ 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_gisa_disable(struct kvm *kvm);
+void kvm_s390_gisa_enable(struct kvm *kvm);
 int kvm_s390_gib_init(u8 nisc);
 void kvm_s390_gib_destroy(void);
 
-- 
2.32.0