[PATCH v3] KVM: s390: exitless interrupt support for KVM

[PATCH v3] KVM: s390: exitless interrupt support for KVM

[Christian Borntraeger]

just the changed patches due to comments for v2. (So any feedback for
other patches against this mail thread)

[PATCH v3 04/12] KVM: s390: implement GISA IPM related primitives

[Christian Borntraeger]

From: Michael Mueller <mimu@linux.vnet.ibm.com>

The patch implements routines to access the GISA to test and modify
its Interruption Pending Mask (IPM) from the host side.

Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/interrupt.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index b7b2865..ec50d42 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -203,6 +203,34 @@ static inline u8 int_word_to_isc(u32 int_word)
 	return (int_word & 0x38000000) >> 27;
 }
 
+/*
+ * To use atomic bitmap functions, we have to provide a bitmap address
+ * that is u64 aligned. However, the ipm might be u32 aligned.
+ * Therefore, we logically start the bitmap at the very beginning of the
+ * struct and fixup the bit number.
+ */
+#define IPM_BIT_OFFSET (offsetof(struct kvm_s390_gisa, ipm) * BITS_PER_BYTE)
+
+static inline void kvm_s390_gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
+{
+	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+}
+
+static inline u8 kvm_s390_gisa_get_ipm(struct kvm_s390_gisa *gisa)
+{
+	return READ_ONCE(gisa->ipm);
+}
+
+static inline void kvm_s390_gisa_clear_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
+{
+	clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+}
+
+static inline int kvm_s390_gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
+{
+	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+}
+
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
 	return vcpu->kvm->arch.float_int.pending_irqs |
-- 
2.9.4

[PATCH v3 06/12] KVM: s390: exploit GISA and AIV for emulated interrupts

[Christian Borntraeger]

From: Michael Mueller <mimu@linux.vnet.ibm.com>

The adapter interruption virtualization (AIV) facility is an
optional facility that comes with functionality expected to increase
the performance of adapter interrupt handling for both emulated and
passed-through adapter interrupts. With AIV, adapter interrupts can be
delivered to the guest without exiting SIE.

This patch provides some preparations for using AIV for emulated adapter
interrupts (inclusive virtio) if it's available. When using AIV, the
interrupts are delivered at the so called GISA by setting the bit
corresponding to its Interruption Subclass (ISC) in the Interruption
Pending Mask (IPM) instead of inserting a node into the floating interrupt
list.

To keep the change reasonably small, the handling of this new state is
deferred in get_all_floating_irqs and handle_tpi. This patch concentrates
on the code handling enqueuement of emulated adapter interrupts, and their
delivery to the guest.

Note that care is still required for adapter interrupts using AIV,
because there is no guarantee that AIV is going to deliver the adapter
interrupts pending at the GISA (consider all vcpus idle). When delivering
GISA adapter interrupts by the host (usual mechanism) special attention
is required to honor interrupt priorities.

Empirical results show that the time window between making an interrupt
pending at the GISA and doing kvm_s390_deliver_pending_interrupts is
sufficient for a guest with at least moderate cpu activity to get adapter
interrupts delivered within the SIE, and potentially save some SIE exits
(if not other deliverable interrupts).

The code will be activated with a follow-up patch.

Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  1 +
 arch/s390/kvm/interrupt.c        | 93 ++++++++++++++++++++++++++++++++--------
 arch/s390/kvm/kvm-s390.c         |  8 ++++
 arch/s390/kvm/kvm-s390.h         |  3 ++
 4 files changed, 87 insertions(+), 18 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 77acade..6802d5d 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -772,6 +772,7 @@ struct kvm_arch{
 	struct kvm_s390_migration_state *migration_state;
 	/* 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;
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index ec50d42..1391199 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -234,7 +234,8 @@ static inline int kvm_s390_gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gis
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
 	return vcpu->kvm->arch.float_int.pending_irqs |
-	       vcpu->arch.local_int.pending_irqs;
+		vcpu->arch.local_int.pending_irqs |
+		kvm_s390_gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
 }
 
 static inline int isc_to_irq_type(unsigned long isc)
@@ -924,18 +925,38 @@ static int __must_check __deliver_virtio(struct kvm_vcpu *vcpu)
 	return rc ? -EFAULT : 0;
 }
 
+static int __do_deliver_io(struct kvm_vcpu *vcpu, struct kvm_s390_io_info *io)
+{
+	int rc;
+
+	rc  = put_guest_lc(vcpu, io->subchannel_id, (u16 *)__LC_SUBCHANNEL_ID);
+	rc |= put_guest_lc(vcpu, io->subchannel_nr, (u16 *)__LC_SUBCHANNEL_NR);
+	rc |= put_guest_lc(vcpu, io->io_int_parm, (u32 *)__LC_IO_INT_PARM);
+	rc |= put_guest_lc(vcpu, io->io_int_word, (u32 *)__LC_IO_INT_WORD);
+	rc |= write_guest_lc(vcpu, __LC_IO_OLD_PSW,
+			     &vcpu->arch.sie_block->gpsw,
+			     sizeof(psw_t));
+	rc |= read_guest_lc(vcpu, __LC_IO_NEW_PSW,
+			    &vcpu->arch.sie_block->gpsw,
+			    sizeof(psw_t));
+	return rc ? -EFAULT : 0;
+}
+
 static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 				     unsigned long irq_type)
 {
 	struct list_head *isc_list;
 	struct kvm_s390_float_interrupt *fi;
 	struct kvm_s390_interrupt_info *inti = NULL;
+	struct kvm_s390_io_info io;
+	u32 isc;
 	int rc = 0;
 
 	fi = &vcpu->kvm->arch.float_int;
 
 	spin_lock(&fi->lock);
-	isc_list = &fi->lists[irq_type_to_isc(irq_type)];
+	isc = irq_type_to_isc(irq_type);
+	isc_list = &fi->lists[isc];
 	inti = list_first_entry_or_null(isc_list,
 					struct kvm_s390_interrupt_info,
 					list);
@@ -963,24 +984,31 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 	spin_unlock(&fi->lock);
 
 	if (inti) {
-		rc  = put_guest_lc(vcpu, inti->io.subchannel_id,
-				(u16 *)__LC_SUBCHANNEL_ID);
-		rc |= put_guest_lc(vcpu, inti->io.subchannel_nr,
-				(u16 *)__LC_SUBCHANNEL_NR);
-		rc |= put_guest_lc(vcpu, inti->io.io_int_parm,
-				(u32 *)__LC_IO_INT_PARM);
-		rc |= put_guest_lc(vcpu, inti->io.io_int_word,
-				(u32 *)__LC_IO_INT_WORD);
-		rc |= write_guest_lc(vcpu, __LC_IO_OLD_PSW,
-				&vcpu->arch.sie_block->gpsw,
-				sizeof(psw_t));
-		rc |= read_guest_lc(vcpu, __LC_IO_NEW_PSW,
-				&vcpu->arch.sie_block->gpsw,
-				sizeof(psw_t));
+		rc = __do_deliver_io(vcpu, &(inti->io));
 		kfree(inti);
+		goto out;
 	}
 
-	return rc ? -EFAULT : 0;
+	if (vcpu->kvm->arch.gisa &&
+	    kvm_s390_gisa_tac_ipm_gisc(vcpu->kvm->arch.gisa, isc)) {
+		/*
+		 * in case an adapter interrupt was not delivered
+		 * in SIE context KVM will handle the delivery
+		 */
+		VCPU_EVENT(vcpu, 4, "%s isc %u", "deliver: I/O (AI/gisa)", isc);
+		memset(&io, 0, sizeof(io));
+		io.io_int_word = (isc << 27) | 0x80000000;
+		vcpu->stat.deliver_io_int++;
+		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id,
+			KVM_S390_INT_IO(1, 0, 0, 0),
+			((__u32)io.subchannel_id << 16) |
+			io.subchannel_nr,
+			((__u64)io.io_int_parm << 32) |
+			io.io_int_word);
+		rc = __do_deliver_io(vcpu, &io);
+	}
+out:
+	return rc;
 }
 
 typedef int (*deliver_irq_t)(struct kvm_vcpu *vcpu);
@@ -1544,6 +1572,15 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 	struct list_head *list;
 	int isc;
 
+	isc = int_word_to_isc(inti->io.io_int_word);
+
+	if (kvm->arch.gisa && inti->type & KVM_S390_INT_IO_AI_MASK) {
+		VM_EVENT(kvm, 4, "%s isc %1u", "inject: I/O (AI/gisa)", isc);
+		kvm_s390_gisa_set_ipm_gisc(kvm->arch.gisa, isc);
+		kfree(inti);
+		return 0;
+	}
+
 	fi = &kvm->arch.float_int;
 	spin_lock(&fi->lock);
 	if (fi->counters[FIRQ_CNTR_IO] >= KVM_S390_MAX_FLOAT_IRQS) {
@@ -1559,7 +1596,6 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 			inti->io.subchannel_id >> 8,
 			inti->io.subchannel_id >> 1 & 0x3,
 			inti->io.subchannel_nr);
-	isc = int_word_to_isc(inti->io.io_int_word);
 	list = &fi->lists[FIRQ_LIST_IO_ISC_0 + isc];
 	list_add_tail(&inti->list, list);
 	set_bit(isc_to_irq_type(isc), &fi->pending_irqs);
@@ -2710,3 +2746,24 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
 
 	return n;
 }
+
+void kvm_s390_gisa_clear(struct kvm *kvm)
+{
+	if (kvm->arch.gisa) {
+		memset(kvm->arch.gisa, 0, sizeof(struct kvm_s390_gisa));
+		kvm->arch.gisa->next_alert = (u32)(u64)kvm->arch.gisa;
+		VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
+	}
+}
+
+void kvm_s390_gisa_init(struct kvm *kvm)
+{
+	/* not implemented yet */
+}
+
+void kvm_s390_gisa_destroy(struct kvm *kvm)
+{
+	if (!kvm->arch.gisa)
+		return;
+	kvm->arch.gisa = NULL;
+}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 48f0099..68d7eef 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1986,6 +1986,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 
 	spin_lock_init(&kvm->arch.start_stop_lock);
 	kvm_s390_vsie_init(kvm);
+	kvm_s390_gisa_init(kvm);
 	KVM_EVENT(3, "vm 0x%pK created by pid %u", kvm, current->pid);
 
 	return 0;
@@ -2048,6 +2049,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kvm_free_vcpus(kvm);
 	sca_dispose(kvm);
 	debug_unregister(kvm->arch.dbf);
+	kvm_s390_gisa_destroy(kvm);
 	free_page((unsigned long)kvm->arch.sie_page2);
 	if (!kvm_is_ucontrol(kvm))
 		gmap_remove(kvm->arch.gmap);
@@ -2458,6 +2460,11 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 	if (test_kvm_facility(vcpu->kvm, 139))
 		vcpu->arch.sie_block->ecd |= ECD_MEF;
 
+	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);
+	}
 	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;
@@ -2510,6 +2517,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
 
 	vcpu->arch.sie_block->icpua = id;
 	spin_lock_init(&vcpu->arch.local_int.lock);
+	vcpu->arch.sie_block->gd = (u32)(u64)kvm->arch.gisa;
 	seqcount_init(&vcpu->arch.cputm_seqcount);
 
 	rc = kvm_vcpu_init(vcpu, kvm, id);
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 8877116..05269a9 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -367,6 +367,9 @@ int kvm_s390_set_irq_state(struct kvm_vcpu *vcpu,
 			   void __user *buf, int len);
 int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu,
 			   __u8 __user *buf, int len);
+void kvm_s390_gisa_init(struct kvm *kvm);
+void kvm_s390_gisa_clear(struct kvm *kvm);
+void kvm_s390_gisa_destroy(struct kvm *kvm);
 
 /* implemented in guestdbg.c */
 void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu);
-- 
2.9.4

[PATCH v3 07/12] KVM: s390: abstract adapter interruption word generation from ISC

[Christian Borntraeger]

From: Michael Mueller <mimu@linux.vnet.ibm.com>

The function isc_to_int_word() allows the generation of interruption
words for adapter interrupts.

Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/interrupt.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 1391199..16075af 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -198,6 +198,11 @@ static uint64_t isc_to_isc_bits(int isc)
 	return (0x80 >> isc) << 24;
 }
 
+static inline u32 isc_to_int_word(u8 isc)
+{
+	return ((u32)isc << 27) | 0x80000000;
+}
+
 static inline u8 int_word_to_isc(u32 int_word)
 {
 	return (int_word & 0x38000000) >> 27;
@@ -997,7 +1002,7 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 		 */
 		VCPU_EVENT(vcpu, 4, "%s isc %u", "deliver: I/O (AI/gisa)", isc);
 		memset(&io, 0, sizeof(io));
-		io.io_int_word = (isc << 27) | 0x80000000;
+		io.io_int_word = isc_to_int_word(isc);
 		vcpu->stat.deliver_io_int++;
 		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id,
 			KVM_S390_INT_IO(1, 0, 0, 0),
@@ -2304,7 +2309,7 @@ static int kvm_s390_inject_airq(struct kvm *kvm,
 	struct kvm_s390_interrupt s390int = {
 		.type = KVM_S390_INT_IO(1, 0, 0, 0),
 		.parm = 0,
-		.parm64 = (adapter->isc << 27) | 0x80000000,
+		.parm64 = isc_to_int_word(adapter->isc),
 	};
 	int ret = 0;
 
-- 
2.9.4

[PATCH v3 10/12] KVM: s390: activate GISA for emulated interrupts

[Christian Borntraeger]

From: Michael Mueller <mimu@linux.vnet.ibm.com>

If the AIV facility is available, a GISA will be used to manage emulated
adapter interrupts.

Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/kvm/interrupt.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 1a561ad..ec4b7bf 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2840,7 +2840,13 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
 
 void kvm_s390_gisa_init(struct kvm *kvm)
 {
-	/* not implemented yet */
+	if (!css_general_characteristics.aiv)
+		kvm->arch.gisa = NULL;
+	else {
+		kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
+		VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
+		kvm_s390_gisa_clear(kvm);
+	}
 }
 
 void kvm_s390_gisa_destroy(struct kvm *kvm)
-- 
2.9.4

Re: [PATCH v3 04/12] KVM: s390: implement GISA IPM related primitives

[David Hildenbrand]

On 25.01.2018 18:06, Christian Borntraeger wrote:
> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> The patch implements routines to access the GISA to test and modify
> its Interruption Pending Mask (IPM) from the host side.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index b7b2865..ec50d42 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -203,6 +203,34 @@ static inline u8 int_word_to_isc(u32 int_word)
>  	return (int_word & 0x38000000) >> 27;
>  }
>  
> +/*
> + * To use atomic bitmap functions, we have to provide a bitmap address
> + * that is u64 aligned. However, the ipm might be u32 aligned.
> + * Therefore, we logically start the bitmap at the very beginning of the
> + * struct and fixup the bit number.
> + */
> +#define IPM_BIT_OFFSET (offsetof(struct kvm_s390_gisa, ipm) * BITS_PER_BYTE)
> +
> +static inline void kvm_s390_gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> +{
> +	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
> +}
> +
> +static inline u8 kvm_s390_gisa_get_ipm(struct kvm_s390_gisa *gisa)
> +{
> +	return READ_ONCE(gisa->ipm);
> +}
> +
> +static inline void kvm_s390_gisa_clear_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> +{
> +	clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
> +}
> +
> +static inline int kvm_s390_gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
> +{
> +	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
> +}
> +
>  static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
>  {
>  	return vcpu->kvm->arch.float_int.pending_irqs |
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb

Re: [PATCH v3 06/12] KVM: s390: exploit GISA and AIV for emulated interrupts

[David Hildenbrand]

On 25.01.2018 18:06, Christian Borntraeger wrote:
> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> The adapter interruption virtualization (AIV) facility is an
> optional facility that comes with functionality expected to increase
> the performance of adapter interrupt handling for both emulated and
> passed-through adapter interrupts. With AIV, adapter interrupts can be
> delivered to the guest without exiting SIE.
> 
> This patch provides some preparations for using AIV for emulated adapter
> interrupts (inclusive virtio) if it's available. When using AIV, the
> interrupts are delivered at the so called GISA by setting the bit
> corresponding to its Interruption Subclass (ISC) in the Interruption
> Pending Mask (IPM) instead of inserting a node into the floating interrupt
> list.
> 
> To keep the change reasonably small, the handling of this new state is
> deferred in get_all_floating_irqs and handle_tpi. This patch concentrates
> on the code handling enqueuement of emulated adapter interrupts, and their
> delivery to the guest.
> 
> Note that care is still required for adapter interrupts using AIV,
> because there is no guarantee that AIV is going to deliver the adapter
> interrupts pending at the GISA (consider all vcpus idle). When delivering
> GISA adapter interrupts by the host (usual mechanism) special attention
> is required to honor interrupt priorities.
> 
> Empirical results show that the time window between making an interrupt
> pending at the GISA and doing kvm_s390_deliver_pending_interrupts is
> sufficient for a guest with at least moderate cpu activity to get adapter
> interrupts delivered within the SIE, and potentially save some SIE exits
> (if not other deliverable interrupts).
> 
> The code will be activated with a follow-up patch.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |  1 +
>  arch/s390/kvm/interrupt.c        | 93 ++++++++++++++++++++++++++++++++--------
>  arch/s390/kvm/kvm-s390.c         |  8 ++++
>  arch/s390/kvm/kvm-s390.h         |  3 ++
>  4 files changed, 87 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
> index 77acade..6802d5d 100644
> --- a/arch/s390/include/asm/kvm_host.h
> +++ b/arch/s390/include/asm/kvm_host.h
> @@ -772,6 +772,7 @@ struct kvm_arch{
>  	struct kvm_s390_migration_state *migration_state;
>  	/* 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;
>  };
>  
>  #define KVM_HVA_ERR_BAD		(-1UL)
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index ec50d42..1391199 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -234,7 +234,8 @@ static inline int kvm_s390_gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gis
>  static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
>  {
>  	return vcpu->kvm->arch.float_int.pending_irqs |
> -	       vcpu->arch.local_int.pending_irqs;
> +		vcpu->arch.local_int.pending_irqs |
> +		kvm_s390_gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
>  }
>  
>  static inline int isc_to_irq_type(unsigned long isc)
> @@ -924,18 +925,38 @@ static int __must_check __deliver_virtio(struct kvm_vcpu *vcpu)
>  	return rc ? -EFAULT : 0;
>  }
>  
> +static int __do_deliver_io(struct kvm_vcpu *vcpu, struct kvm_s390_io_info *io)
> +{
> +	int rc;
> +
> +	rc  = put_guest_lc(vcpu, io->subchannel_id, (u16 *)__LC_SUBCHANNEL_ID);
> +	rc |= put_guest_lc(vcpu, io->subchannel_nr, (u16 *)__LC_SUBCHANNEL_NR);
> +	rc |= put_guest_lc(vcpu, io->io_int_parm, (u32 *)__LC_IO_INT_PARM);
> +	rc |= put_guest_lc(vcpu, io->io_int_word, (u32 *)__LC_IO_INT_WORD);
> +	rc |= write_guest_lc(vcpu, __LC_IO_OLD_PSW,
> +			     &vcpu->arch.sie_block->gpsw,
> +			     sizeof(psw_t));
> +	rc |= read_guest_lc(vcpu, __LC_IO_NEW_PSW,
> +			    &vcpu->arch.sie_block->gpsw,
> +			    sizeof(psw_t));
> +	return rc ? -EFAULT : 0;
> +}
> +
>  static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
>  				     unsigned long irq_type)
>  {
>  	struct list_head *isc_list;
>  	struct kvm_s390_float_interrupt *fi;
>  	struct kvm_s390_interrupt_info *inti = NULL;
> +	struct kvm_s390_io_info io;
> +	u32 isc;
>  	int rc = 0;
>  
>  	fi = &vcpu->kvm->arch.float_int;
>  
>  	spin_lock(&fi->lock);
> -	isc_list = &fi->lists[irq_type_to_isc(irq_type)];
> +	isc = irq_type_to_isc(irq_type);
> +	isc_list = &fi->lists[isc];
>  	inti = list_first_entry_or_null(isc_list,
>  					struct kvm_s390_interrupt_info,
>  					list);
> @@ -963,24 +984,31 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
>  	spin_unlock(&fi->lock);
>  
>  	if (inti) {
> -		rc  = put_guest_lc(vcpu, inti->io.subchannel_id,
> -				(u16 *)__LC_SUBCHANNEL_ID);
> -		rc |= put_guest_lc(vcpu, inti->io.subchannel_nr,
> -				(u16 *)__LC_SUBCHANNEL_NR);
> -		rc |= put_guest_lc(vcpu, inti->io.io_int_parm,
> -				(u32 *)__LC_IO_INT_PARM);
> -		rc |= put_guest_lc(vcpu, inti->io.io_int_word,
> -				(u32 *)__LC_IO_INT_WORD);
> -		rc |= write_guest_lc(vcpu, __LC_IO_OLD_PSW,
> -				&vcpu->arch.sie_block->gpsw,
> -				sizeof(psw_t));
> -		rc |= read_guest_lc(vcpu, __LC_IO_NEW_PSW,
> -				&vcpu->arch.sie_block->gpsw,
> -				sizeof(psw_t));
> +		rc = __do_deliver_io(vcpu, &(inti->io));
>  		kfree(inti);
> +		goto out;
>  	}
>  
> -	return rc ? -EFAULT : 0;
> +	if (vcpu->kvm->arch.gisa &&
> +	    kvm_s390_gisa_tac_ipm_gisc(vcpu->kvm->arch.gisa, isc)) {
> +		/*
> +		 * in case an adapter interrupt was not delivered
> +		 * in SIE context KVM will handle the delivery
> +		 */
> +		VCPU_EVENT(vcpu, 4, "%s isc %u", "deliver: I/O (AI/gisa)", isc);
> +		memset(&io, 0, sizeof(io));
> +		io.io_int_word = (isc << 27) | 0x80000000;
> +		vcpu->stat.deliver_io_int++;
> +		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id,
> +			KVM_S390_INT_IO(1, 0, 0, 0),
> +			((__u32)io.subchannel_id << 16) |
> +			io.subchannel_nr,
> +			((__u64)io.io_int_parm << 32) |
> +			io.io_int_word);
> +		rc = __do_deliver_io(vcpu, &io);
> +	}
> +out:
> +	return rc;
>  }
>  
>  typedef int (*deliver_irq_t)(struct kvm_vcpu *vcpu);
> @@ -1544,6 +1572,15 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
>  	struct list_head *list;
>  	int isc;
>  
> +	isc = int_word_to_isc(inti->io.io_int_word);
> +
> +	if (kvm->arch.gisa && inti->type & KVM_S390_INT_IO_AI_MASK) {
> +		VM_EVENT(kvm, 4, "%s isc %1u", "inject: I/O (AI/gisa)", isc);
> +		kvm_s390_gisa_set_ipm_gisc(kvm->arch.gisa, isc);
> +		kfree(inti);
> +		return 0;
> +	}
> +
>  	fi = &kvm->arch.float_int;
>  	spin_lock(&fi->lock);
>  	if (fi->counters[FIRQ_CNTR_IO] >= KVM_S390_MAX_FLOAT_IRQS) {
> @@ -1559,7 +1596,6 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
>  			inti->io.subchannel_id >> 8,
>  			inti->io.subchannel_id >> 1 & 0x3,
>  			inti->io.subchannel_nr);
> -	isc = int_word_to_isc(inti->io.io_int_word);
>  	list = &fi->lists[FIRQ_LIST_IO_ISC_0 + isc];
>  	list_add_tail(&inti->list, list);
>  	set_bit(isc_to_irq_type(isc), &fi->pending_irqs);
> @@ -2710,3 +2746,24 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
>  
>  	return n;
>  }
> +
> +void kvm_s390_gisa_clear(struct kvm *kvm)
> +{
> +	if (kvm->arch.gisa) {
> +		memset(kvm->arch.gisa, 0, sizeof(struct kvm_s390_gisa));
> +		kvm->arch.gisa->next_alert = (u32)(u64)kvm->arch.gisa;
> +		VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
> +	}
> +}
> +
> +void kvm_s390_gisa_init(struct kvm *kvm)
> +{
> +	/* not implemented yet */
> +}
> +
> +void kvm_s390_gisa_destroy(struct kvm *kvm)
> +{
> +	if (!kvm->arch.gisa)
> +		return;
> +	kvm->arch.gisa = NULL;
> +}
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 48f0099..68d7eef 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -1986,6 +1986,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
>  
>  	spin_lock_init(&kvm->arch.start_stop_lock);
>  	kvm_s390_vsie_init(kvm);
> +	kvm_s390_gisa_init(kvm);
>  	KVM_EVENT(3, "vm 0x%pK created by pid %u", kvm, current->pid);
>  
>  	return 0;
> @@ -2048,6 +2049,7 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
>  	kvm_free_vcpus(kvm);
>  	sca_dispose(kvm);
>  	debug_unregister(kvm->arch.dbf);
> +	kvm_s390_gisa_destroy(kvm);
>  	free_page((unsigned long)kvm->arch.sie_page2);
>  	if (!kvm_is_ucontrol(kvm))
>  		gmap_remove(kvm->arch.gmap);
> @@ -2458,6 +2460,11 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
>  	if (test_kvm_facility(vcpu->kvm, 139))
>  		vcpu->arch.sie_block->ecd |= ECD_MEF;
>  
> +	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);
> +	}
>  	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;
> @@ -2510,6 +2517,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm,
>  
>  	vcpu->arch.sie_block->icpua = id;
>  	spin_lock_init(&vcpu->arch.local_int.lock);
> +	vcpu->arch.sie_block->gd = (u32)(u64)kvm->arch.gisa;
>  	seqcount_init(&vcpu->arch.cputm_seqcount);
>  
>  	rc = kvm_vcpu_init(vcpu, kvm, id);
> diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
> index 8877116..05269a9 100644
> --- a/arch/s390/kvm/kvm-s390.h
> +++ b/arch/s390/kvm/kvm-s390.h
> @@ -367,6 +367,9 @@ int kvm_s390_set_irq_state(struct kvm_vcpu *vcpu,
>  			   void __user *buf, int len);
>  int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu,
>  			   __u8 __user *buf, int len);
> +void kvm_s390_gisa_init(struct kvm *kvm);
> +void kvm_s390_gisa_clear(struct kvm *kvm);
> +void kvm_s390_gisa_destroy(struct kvm *kvm);
>  
>  /* implemented in guestdbg.c */
>  void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu);
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb

Re: [PATCH v3 07/12] KVM: s390: abstract adapter interruption word generation from ISC

[David Hildenbrand]

On 25.01.2018 18:06, Christian Borntraeger wrote:
> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> The function isc_to_int_word() allows the generation of interruption
> words for adapter interrupts.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 1391199..16075af 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -198,6 +198,11 @@ static uint64_t isc_to_isc_bits(int isc)
>  	return (0x80 >> isc) << 24;
>  }
>  
> +static inline u32 isc_to_int_word(u8 isc)
> +{
> +	return ((u32)isc << 27) | 0x80000000;
> +}
> +
>  static inline u8 int_word_to_isc(u32 int_word)
>  {
>  	return (int_word & 0x38000000) >> 27;
> @@ -997,7 +1002,7 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
>  		 */
>  		VCPU_EVENT(vcpu, 4, "%s isc %u", "deliver: I/O (AI/gisa)", isc);
>  		memset(&io, 0, sizeof(io));
> -		io.io_int_word = (isc << 27) | 0x80000000;
> +		io.io_int_word = isc_to_int_word(isc);
>  		vcpu->stat.deliver_io_int++;
>  		trace_kvm_s390_deliver_interrupt(vcpu->vcpu_id,
>  			KVM_S390_INT_IO(1, 0, 0, 0),
> @@ -2304,7 +2309,7 @@ static int kvm_s390_inject_airq(struct kvm *kvm,
>  	struct kvm_s390_interrupt s390int = {
>  		.type = KVM_S390_INT_IO(1, 0, 0, 0),
>  		.parm = 0,
> -		.parm64 = (adapter->isc << 27) | 0x80000000,
> +		.parm64 = isc_to_int_word(adapter->isc),
>  	};
>  	int ret = 0;
>  
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb

Re: [PATCH v3 10/12] KVM: s390: activate GISA for emulated interrupts

[David Hildenbrand]

On 25.01.2018 18:06, Christian Borntraeger wrote:
> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> If the AIV facility is available, a GISA will be used to manage emulated
> adapter interrupts.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index 1a561ad..ec4b7bf 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -2840,7 +2840,13 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
>  
>  void kvm_s390_gisa_init(struct kvm *kvm)
>  {
> -	/* not implemented yet */
> +	if (!css_general_characteristics.aiv)
> +		kvm->arch.gisa = NULL;
> +	else {

Hmm, isn't it NULL as default?

if (css_general_characteristics.aiv) {

...

Anyhow,

Reviewed-by: David Hildenbrand <david@redhat.com>

> +		kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
> +		VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
> +		kvm_s390_gisa_clear(kvm);
> +	}
>  }
>  
>  void kvm_s390_gisa_destroy(struct kvm *kvm)
> 


-- 

Thanks,

David / dhildenb

Re: [PATCH v3 10/12] KVM: s390: activate GISA for emulated interrupts

[Christian Borntraeger]

On 01/25/2018 06:38 PM, David Hildenbrand wrote:
> On 25.01.2018 18:06, Christian Borntraeger wrote:
>> From: Michael Mueller <mimu@linux.vnet.ibm.com>
>>
>> If the AIV facility is available, a GISA will be used to manage emulated
>> adapter interrupts.
>>
>> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
>> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
>> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  arch/s390/kvm/interrupt.c | 8 +++++++-
>>  1 file changed, 7 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
>> index 1a561ad..ec4b7bf 100644
>> --- a/arch/s390/kvm/interrupt.c
>> +++ b/arch/s390/kvm/interrupt.c
>> @@ -2840,7 +2840,13 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
>>  
>>  void kvm_s390_gisa_init(struct kvm *kvm)
>>  {
>> -	/* not implemented yet */
>> +	if (!css_general_characteristics.aiv)
>> +		kvm->arch.gisa = NULL;
>> +	else {
> 
> Hmm, isn't it NULL as default?
> 
> if (css_general_characteristics.aiv) {

Indeed kvm arch is zero allocated. Will drop.

> 
> ...
> 
> Anyhow,
> 
> Reviewed-by: David Hildenbrand <david@redhat.com>

Thanks. I will add these patches for my next pull request for the next
merge window. Last chance to review the other patches (see v2).



> 
>> +		kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
>> +		VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
>> +		kvm_s390_gisa_clear(kvm);
>> +	}
>>  }
>>  
>>  void kvm_s390_gisa_destroy(struct kvm *kvm)
>>
> 
> 

Re: [PATCH v3 04/12] KVM: s390: implement GISA IPM related primitives

[Cornelia Huck]

On Thu, 25 Jan 2018 18:06:05 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> The patch implements routines to access the GISA to test and modify
> its Interruption Pending Mask (IPM) from the host side.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v3 06/12] KVM: s390: exploit GISA and AIV for emulated interrupts

[Cornelia Huck]

On Thu, 25 Jan 2018 18:06:06 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> The adapter interruption virtualization (AIV) facility is an
> optional facility that comes with functionality expected to increase
> the performance of adapter interrupt handling for both emulated and
> passed-through adapter interrupts. With AIV, adapter interrupts can be
> delivered to the guest without exiting SIE.
> 
> This patch provides some preparations for using AIV for emulated adapter
> interrupts (inclusive virtio) if it's available. When using AIV, the

s/inclusive/including/

> interrupts are delivered at the so called GISA by setting the bit
> corresponding to its Interruption Subclass (ISC) in the Interruption
> Pending Mask (IPM) instead of inserting a node into the floating interrupt
> list.
> 
> To keep the change reasonably small, the handling of this new state is
> deferred in get_all_floating_irqs and handle_tpi. This patch concentrates
> on the code handling enqueuement of emulated adapter interrupts, and their
> delivery to the guest.
> 
> Note that care is still required for adapter interrupts using AIV,
> because there is no guarantee that AIV is going to deliver the adapter
> interrupts pending at the GISA (consider all vcpus idle). When delivering
> GISA adapter interrupts by the host (usual mechanism) special attention
> is required to honor interrupt priorities.
> 
> Empirical results show that the time window between making an interrupt
> pending at the GISA and doing kvm_s390_deliver_pending_interrupts is
> sufficient for a guest with at least moderate cpu activity to get adapter
> interrupts delivered within the SIE, and potentially save some SIE exits
> (if not other deliverable interrupts).
> 
> The code will be activated with a follow-up patch.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |  1 +
>  arch/s390/kvm/interrupt.c        | 93 ++++++++++++++++++++++++++++++++--------
>  arch/s390/kvm/kvm-s390.c         |  8 ++++
>  arch/s390/kvm/kvm-s390.h         |  3 ++
>  4 files changed, 87 insertions(+), 18 deletions(-)
> 

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v3 10/12] KVM: s390: activate GISA for emulated interrupts

[Cornelia Huck]

On Thu, 25 Jan 2018 18:06:08 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> From: Michael Mueller <mimu@linux.vnet.ibm.com>
> 
> If the AIV facility is available, a GISA will be used to manage emulated
> adapter interrupts.
> 
> Signed-off-by: Michael Mueller <mimu@linux.vnet.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.vnet.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)

Reviewed-by: Cornelia Huck <cohuck@redhat.com>