[PATCH v7 00/15] KVM: s390: make use of the GIB

[PATCH v7 00/15] KVM: s390: make use of the GIB

[Michael Mueller]

The Guest Information Area (GIB) and its mechanics is part of
the AIV facility. It provides hardware support to process
Adapter Interruptions (AI) for pagable storage mode guests. 

Whenever a guest cannot process an AI because none of its
vcpus is running in SIE context, a GIB alert interruption is
sent to and handled by the host program to dispatch a vcpu of
the respective guest.

Eventually, the AI is handled by the guest.

v6->v7:
  patches 1/15 to 7/15
     prepare the existing Interruption and GISA code for
     the introduction of the GIB code. (kept from v6)
  patches 8/15 to 10/15
     kept from v6.
  patch 11/15
     kvm_s390_gisc_register() now uses a single conditional
     branch to extend IAM restore value and to set the IAM
     in GISA. 
  patch 12/15
     kvm_s390_clear_gisa() now refactored in its own patch.
  patch 13/15
     I'm keeping the 50 usec timer expiration as the statistic
     data shows a single timer restart only.
       gisa_get_ipm_or_restore_iam() now called when entering
     kvm_s390_handle_wait(). That saves some of the timer
     restarts.
       Some modifications in kvm_s390_gisa_destroy()
  patch 14/15
     kept from v6.
  patch 15/15
     additional test on non NULL gisa origin in pending_irqs()

v5->v6:
  Futher significant change was introduced with this version
  now:

  a) During the alert list processing now a hrtimer is
     started to kick an idle vcpu with open I/O interrupt
     mask. It then is restarted to monitor the interruption
     consumption and when the IPM is clean (no relevant
     ISCs pending anymore) atomically restores the IAM
     and don't restarts or if new ISCs arrive kick other
     idle vcpus.

  patches 1/13 to 7/13:
     prepare the existing Interruption and GISA code for
     the introduction of the GIB code.
  patches 8/13 to 10/13:
     kept from v5.
  patch 11/13:
     Some comments added.
  patch 12/13:
     Significatly changed due to the hrtimer control.
  patch 13/13:
     Basically kept from v5 except for a slight reordering
     that shortens the patch.

v4->v5:
  Between these two versions some significant change was
  introduced:

  a) During IPM look-up, the IAM gets atomically restored
     if the IPM is clean. (The main strategy is: As soon no
     airqs are pending anymore, get prepared for new ones
     arriving).

  b) Kick a set of vcpus in WAIT state, that will be able
     to handle all ISCs in IPM if possible. The main loop
     that processes the GIB alert list is unchanged.

  patches 1/15 to 6/15:
     prepare the existing Interruption and GISA code for
     the introduction of the GIB code.
  patches 7/15 to 9/15:
     kept from v4. 
  patch 10/15:
     restores the IAM in get_ipm() when clean on request
     with additional parameter irq_flags
  patch 12/15:
     modifies kvm_s390_deliver_pending_interrupts() such
     that the IAM is not restored during the deliverable_irqs()
     test as we are about to enter the SIE. Restoring the
     IAM would trigger the alert mechanism unnecessarily
     on SIE entry.
  patch 13/15:
     process_gib_alert_list() now triggers a minimal set
     of idle vcpus capable the handle all pending ISCs.
  patch 14/15:
     the wiring is logical similar to v4 but uses different
     routines
  patch 15/15: 
     kept from v4. 

v3->v4:
  The central change of v4 is that the metric "vcpus_in_sie"
  has been dropped. A least agressive IAM restore strategy
  is being followed now. The consequence is that potentially
  more GAL interruptions are to be handled by the host program.
  The assuption as made that as soon the first vcpu is trying
  to go into wait state, this could be the last vcpu being
  open for I/O interruptions. Thus, to not loose the initiative
  to deliver I/O interruptions as soon as possible, the IAM
  is restored. Adding better heuristics can be done in future.

  I expect this to be the last version of the series.
 
  patch 01/12: Kernel msg now printed when FLIC fails
               to register during arch inititialization.
  patch 03/12: Commit message slightly changed with the
  	       hint that gib initialization is called
	       by last patch of this serias.
  patch 09/12: IAM now restored during kvm_s390_handle_wait()
  patch 10/12: gib destroy case now handled upon unsuccessful
  	       arch inititialization.

All other patches are unchanged.

v2->v3:
  patch 01/12: Fixes a resource dealocation issue upon
  	       unsuccessful exit from kvm_arch_init().
	       It is relevant for patch 11/12 as well. 
  patch 08/12: The function process_gib_alert_list() has
               been rewritten to reduce the number of GAL
	       interruptions on the host for many guest
	       scenarios.
  patch 10/12: The IAM is now never cleared before SIE entry.
               It will be cleared by millicode as soon the
	       first guest interruption is made pending and
	       not directly processed in SIE. The IAM gets
	       restored as soon a vm is idle, i.e. no vcpu
	       of that guest is in SIE context anymore.
  patch 11/12: now integrates with new patch 01/12
  patch 12/12: This patch is just experimental and shall not
               be part of the final series.

The first patch of series v2: "leave AIs in IPM of GISA
during vcpu_pre_run()" has been dropped.

All other patches are unchanged.

v1->v2:
  patch 01/12: New patch. Tt can go also standalone without the
  	       rest of the GIB series presented here but is a
	       requirement 
  patch 03/12: kvm_s390_gib_init() now has a return code
  patch 06/12: unlink_gib_alert_list() now uses cmpxchg() instead
    	       of atomic_xchg()
  patch 08/12: New patch. Foctors out __find_vcpu_for_floating_irq()
  patch 09/12: process_gib_alert_list() has been simplified
               the GISA clear/destroy cases have been removed
  patch 11/12: kvm_s390_gisa_clear/destroy() now clear the IAM
               and process the alert list directly
	       The IAM now gets restored in vcpu_post_run() only if
	       the GISA is not in alert list
  patch 12/12: during kvm_arch_init() now the return code of
    	       kvm_s390_gib_init() is honored.

All other patches are unchanged.

Michael Mueller (15):
  KVM: s390: drop obsolete else path
  KVM: s390: make bitmap declaration consistent
  KVM: s390: move bitmap idle_mask into arch struct top level
  KVM: s390: coding style kvm_s390_gisa_init/clear()
  KVM: s390: use pending_irqs_no_gisa() where appropriate
  KVM: s390: remove kvm_s390_ from gisa static inline functions
  KVM: s390: introduce struct kvm_s390_gisa_interrupt
  s390/cio: add function chsc_sgib()
  KVM: s390: add the GIB and its related life-cyle functions
  KVM: s390: add kvm reference to struct sie_page2
  KVM: s390: add functions to (un)register GISC with GISA
  KVM: s390: kvm_s390_gisa_clear() now clears the IPM only
  KVM: s390: add gib_alert_irq_handler()
  KVM: s390: start using the GIB
  KVM: s390: fix possible null pointer dereference in pending_irqs()

 arch/s390/include/asm/cio.h      |   1 +
 arch/s390/include/asm/irq.h      |   1 +
 arch/s390/include/asm/isc.h      |   1 +
 arch/s390/include/asm/kvm_host.h |  36 +++-
 arch/s390/kernel/irq.c           |   1 +
 arch/s390/kvm/interrupt.c        | 431 +++++++++++++++++++++++++++++++++++----
 arch/s390/kvm/kvm-s390.c         |  13 +-
 arch/s390/kvm/kvm-s390.h         |   4 +-
 drivers/s390/cio/chsc.c          |  37 ++++
 drivers/s390/cio/chsc.h          |   1 +
 10 files changed, 480 insertions(+), 46 deletions(-)

-- 
2.13.4

[PATCH v7 01/15] KVM: s390: drop obsolete else path

[Michael Mueller]

The explicit else path specified in set_intercept_indicators_io
is not required as the function returns in case the first branch
is taken anyway.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index fcb55b02990e..19d556512452 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -345,7 +345,7 @@ static void set_intercept_indicators_io(struct kvm_vcpu *vcpu)
 {
 	if (!(pending_irqs_no_gisa(vcpu) & IRQ_PEND_IO_MASK))
 		return;
-	else if (psw_ioint_disabled(vcpu))
+	if (psw_ioint_disabled(vcpu))
 		kvm_s390_set_cpuflags(vcpu, CPUSTAT_IO_INT);
 	else
 		vcpu->arch.sie_block->lctl |= LCTL_CR6;
-- 
2.13.4

[PATCH v7 02/15] KVM: s390: make bitmap declaration consistent

[Michael Mueller]

Use a consistent bitmap declaration throughout the code.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h | 2 +-
 arch/s390/kvm/interrupt.c        | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index d5d24889c3bc..3cba08f73dc6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -591,7 +591,7 @@ struct kvm_s390_float_interrupt {
 	struct kvm_s390_mchk_info mchk;
 	struct kvm_s390_ext_info srv_signal;
 	int next_rr_cpu;
-	unsigned long idle_mask[BITS_TO_LONGS(KVM_MAX_VCPUS)];
+	DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS);
 	struct mutex ais_lock;
 	u8 simm;
 	u8 nimm;
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 19d556512452..167a3068ef84 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2831,7 +2831,7 @@ static void store_local_irq(struct kvm_s390_local_interrupt *li,
 int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
 {
 	int scn;
-	unsigned long sigp_emerg_pending[BITS_TO_LONGS(KVM_MAX_VCPUS)];
+	DECLARE_BITMAP(sigp_emerg_pending, KVM_MAX_VCPUS);
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
 	unsigned long pending_irqs;
 	struct kvm_s390_irq irq;
-- 
2.13.4

[PATCH v7 03/15] KVM: s390: move bitmap idle_mask into arch struct top level

[Michael Mueller]

The vcpu idle_mask state is used by but not specific
to the emulated floating interruptions. The state is
relevant to gisa related interruptions as well.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
---
 arch/s390/include/asm/kvm_host.h |  2 +-
 arch/s390/kvm/interrupt.c        | 11 +++++------
 arch/s390/kvm/kvm-s390.h         |  2 +-
 3 files changed, 7 insertions(+), 8 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 3cba08f73dc6..c259a67c4298 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -591,7 +591,6 @@ struct kvm_s390_float_interrupt {
 	struct kvm_s390_mchk_info mchk;
 	struct kvm_s390_ext_info srv_signal;
 	int next_rr_cpu;
-	DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS);
 	struct mutex ais_lock;
 	u8 simm;
 	u8 nimm;
@@ -838,6 +837,7 @@ 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;
+	DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS);
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 167a3068ef84..2a3eb9f076c3 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -318,13 +318,13 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)
 static void __set_cpu_idle(struct kvm_vcpu *vcpu)
 {
 	kvm_s390_set_cpuflags(vcpu, CPUSTAT_WAIT);
-	set_bit(vcpu->vcpu_id, vcpu->kvm->arch.float_int.idle_mask);
+	set_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask);
 }
 
 static void __unset_cpu_idle(struct kvm_vcpu *vcpu)
 {
 	kvm_s390_clear_cpuflags(vcpu, CPUSTAT_WAIT);
-	clear_bit(vcpu->vcpu_id, vcpu->kvm->arch.float_int.idle_mask);
+	clear_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask);
 }
 
 static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
@@ -1726,7 +1726,6 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
  */
 static void __floating_irq_kick(struct kvm *kvm, u64 type)
 {
-	struct kvm_s390_float_interrupt *fi = &kvm->arch.float_int;
 	struct kvm_vcpu *dst_vcpu;
 	int sigcpu, online_vcpus, nr_tries = 0;
 
@@ -1735,11 +1734,11 @@ static void __floating_irq_kick(struct kvm *kvm, u64 type)
 		return;
 
 	/* find idle VCPUs first, then round robin */
-	sigcpu = find_first_bit(fi->idle_mask, online_vcpus);
+	sigcpu = find_first_bit(kvm->arch.idle_mask, online_vcpus);
 	if (sigcpu == online_vcpus) {
 		do {
-			sigcpu = fi->next_rr_cpu;
-			fi->next_rr_cpu = (fi->next_rr_cpu + 1) % online_vcpus;
+			sigcpu = kvm->arch.float_int.next_rr_cpu++;
+			kvm->arch.float_int.next_rr_cpu %= online_vcpus;
 			/* avoid endless loops if all vcpus are stopped */
 			if (nr_tries++ >= online_vcpus)
 				return;
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 1f6e36cdce0d..72ef87799593 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -67,7 +67,7 @@ static inline int is_vcpu_stopped(struct kvm_vcpu *vcpu)
 
 static inline int is_vcpu_idle(struct kvm_vcpu *vcpu)
 {
-	return test_bit(vcpu->vcpu_id, vcpu->kvm->arch.float_int.idle_mask);
+	return test_bit(vcpu->vcpu_id, vcpu->kvm->arch.idle_mask);
 }
 
 static inline int kvm_is_ucontrol(struct kvm *kvm)
-- 
2.13.4

[PATCH v7 04/15] KVM: s390: coding style kvm_s390_gisa_init/clear()

[Michael Mueller]

The change helps to reduce line length and
increases code readability.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 2a3eb9f076c3..005dbe7252e7 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2885,20 +2885,20 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
 
 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);
-	}
+	if (!kvm->arch.gisa)
+		return;
+	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)
 {
-	if (css_general_characteristics.aiv) {
-		kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
-		VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
-		kvm_s390_gisa_clear(kvm);
-	}
+	if (!css_general_characteristics.aiv)
+		return;
+	kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
+	kvm_s390_gisa_clear(kvm);
+	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
 }
 
 void kvm_s390_gisa_destroy(struct kvm *kvm)
-- 
2.13.4

[PATCH v7 05/15] KVM: s390: use pending_irqs_no_gisa() where appropriate

[Michael Mueller]

Interruption types that are not represented in GISA shall
use pending_irqs_no_gisa() to test pending interruptions.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 005dbe7252e7..cb48736867ed 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -353,7 +353,7 @@ static void set_intercept_indicators_io(struct kvm_vcpu *vcpu)
 
 static void set_intercept_indicators_ext(struct kvm_vcpu *vcpu)
 {
-	if (!(pending_irqs(vcpu) & IRQ_PEND_EXT_MASK))
+	if (!(pending_irqs_no_gisa(vcpu) & IRQ_PEND_EXT_MASK))
 		return;
 	if (psw_extint_disabled(vcpu))
 		kvm_s390_set_cpuflags(vcpu, CPUSTAT_EXT_INT);
@@ -363,7 +363,7 @@ static void set_intercept_indicators_ext(struct kvm_vcpu *vcpu)
 
 static void set_intercept_indicators_mchk(struct kvm_vcpu *vcpu)
 {
-	if (!(pending_irqs(vcpu) & IRQ_PEND_MCHK_MASK))
+	if (!(pending_irqs_no_gisa(vcpu) & IRQ_PEND_MCHK_MASK))
 		return;
 	if (psw_mchk_disabled(vcpu))
 		vcpu->arch.sie_block->ictl |= ICTL_LPSW;
-- 
2.13.4

[PATCH v7 06/15] KVM: s390: remove kvm_s390_ from gisa static inline functions

[Michael Mueller]

This will shorten the length of code lines. All GISA related
static inline functions are local to interrupt.c.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index cb48736867ed..942cc7d33766 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -217,22 +217,22 @@ static inline u8 int_word_to_isc(u32 int_word)
  */
 #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)
+static inline void 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)
+static inline u8 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)
+static inline void 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)
+static inline int gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
 	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
 }
@@ -246,7 +246,7 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
 	return pending_irqs_no_gisa(vcpu) |
-		kvm_s390_gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
+		gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
 }
 
 static inline int isc_to_irq_type(unsigned long isc)
@@ -999,7 +999,7 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 	}
 
 	if (vcpu->kvm->arch.gisa &&
-	    kvm_s390_gisa_tac_ipm_gisc(vcpu->kvm->arch.gisa, isc)) {
+	    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
@@ -1541,10 +1541,10 @@ static int get_top_gisa_isc(struct kvm *kvm, u64 isc_mask, u32 schid)
 	if (!kvm->arch.gisa)
 		goto out;
 
-	active_mask = (isc_mask & kvm_s390_gisa_get_ipm(kvm->arch.gisa) << 24) << 32;
+	active_mask = (isc_mask & gisa_get_ipm(kvm->arch.gisa) << 24) << 32;
 	while (active_mask) {
 		isc = __fls(active_mask) ^ (BITS_PER_LONG - 1);
-		if (kvm_s390_gisa_tac_ipm_gisc(kvm->arch.gisa, isc))
+		if (gisa_tac_ipm_gisc(kvm->arch.gisa, isc))
 			return isc;
 		clear_bit_inv(isc, &active_mask);
 	}
@@ -1584,7 +1584,7 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 	/* both types of interrupts present */
 	if (int_word_to_isc(inti->io.io_int_word) <= isc) {
 		/* classical IO int with higher priority */
-		kvm_s390_gisa_set_ipm_gisc(kvm->arch.gisa, isc);
+		gisa_set_ipm_gisc(kvm->arch.gisa, isc);
 		goto out;
 	}
 gisa_out:
@@ -1596,7 +1596,7 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 			kvm_s390_reinject_io_int(kvm, inti);
 		inti = tmp_inti;
 	} else
-		kvm_s390_gisa_set_ipm_gisc(kvm->arch.gisa, isc);
+		gisa_set_ipm_gisc(kvm->arch.gisa, isc);
 out:
 	return inti;
 }
@@ -1694,7 +1694,7 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 
 	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);
+		gisa_set_ipm_gisc(kvm->arch.gisa, isc);
 		kfree(inti);
 		return 0;
 	}
@@ -2025,15 +2025,14 @@ static int get_all_floating_irqs(struct kvm *kvm, u8 __user *usrbuf, u64 len)
 
 	max_irqs = len / sizeof(struct kvm_s390_irq);
 
-	if (kvm->arch.gisa &&
-	    kvm_s390_gisa_get_ipm(kvm->arch.gisa)) {
+	if (kvm->arch.gisa && gisa_get_ipm(kvm->arch.gisa)) {
 		for (i = 0; i <= MAX_ISC; i++) {
 			if (n == max_irqs) {
 				/* signal userspace to try again */
 				ret = -ENOMEM;
 				goto out_nolock;
 			}
-			if (kvm_s390_gisa_tac_ipm_gisc(kvm->arch.gisa, i)) {
+			if (gisa_tac_ipm_gisc(kvm->arch.gisa, i)) {
 				irq = (struct kvm_s390_irq *) &buf[n];
 				irq->type = KVM_S390_INT_IO(1, 0, 0, 0);
 				irq->u.io.io_int_word = isc_to_int_word(i);
-- 
2.13.4

[PATCH v7 07/15] KVM: s390: introduce struct kvm_s390_gisa_interrupt

[Michael Mueller]

Use this struct analog to the kvm interruption structs
for kvm emulated floating and local interruptions.

GIB handling will add further fields to this structure as
required.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  6 ++++-
 arch/s390/kvm/interrupt.c        | 52 +++++++++++++++++++++++-----------------
 arch/s390/kvm/kvm-s390.c         |  2 +-
 3 files changed, 36 insertions(+), 24 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index c259a67c4298..0941571d34eb 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -803,6 +803,10 @@ struct kvm_s390_vsie {
 	struct page *pages[KVM_MAX_VCPUS];
 };
 
+struct kvm_s390_gisa_interrupt {
+	struct kvm_s390_gisa *origin;
+};
+
 struct kvm_arch{
 	void *sca;
 	int use_esca;
@@ -836,8 +840,8 @@ struct kvm_arch{
 	atomic64_t cmma_dirty_pages;
 	/* 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;
 	DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS);
+	struct kvm_s390_gisa_interrupt gisa_int;
 };
 
 #define KVM_HVA_ERR_BAD		(-1UL)
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 942cc7d33766..ee91d1de0036 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -246,7 +246,8 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
 	return pending_irqs_no_gisa(vcpu) |
-		gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
+		gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
+			IRQ_PEND_IO_ISC_7;
 }
 
 static inline int isc_to_irq_type(unsigned long isc)
@@ -956,6 +957,7 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 {
 	struct list_head *isc_list;
 	struct kvm_s390_float_interrupt *fi;
+	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
 	struct kvm_s390_interrupt_info *inti = NULL;
 	struct kvm_s390_io_info io;
 	u32 isc;
@@ -998,8 +1000,7 @@ static int __must_check __deliver_io(struct kvm_vcpu *vcpu,
 		goto out;
 	}
 
-	if (vcpu->kvm->arch.gisa &&
-	    gisa_tac_ipm_gisc(vcpu->kvm->arch.gisa, isc)) {
+	if (gi->origin && gisa_tac_ipm_gisc(gi->origin, isc)) {
 		/*
 		 * in case an adapter interrupt was not delivered
 		 * in SIE context KVM will handle the delivery
@@ -1533,18 +1534,19 @@ static struct kvm_s390_interrupt_info *get_top_io_int(struct kvm *kvm,
 
 static int get_top_gisa_isc(struct kvm *kvm, u64 isc_mask, u32 schid)
 {
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
 	unsigned long active_mask;
 	int isc;
 
 	if (schid)
 		goto out;
-	if (!kvm->arch.gisa)
+	if (!gi->origin)
 		goto out;
 
-	active_mask = (isc_mask & gisa_get_ipm(kvm->arch.gisa) << 24) << 32;
+	active_mask = (isc_mask & gisa_get_ipm(gi->origin) << 24) << 32;
 	while (active_mask) {
 		isc = __fls(active_mask) ^ (BITS_PER_LONG - 1);
-		if (gisa_tac_ipm_gisc(kvm->arch.gisa, isc))
+		if (gisa_tac_ipm_gisc(gi->origin, isc))
 			return isc;
 		clear_bit_inv(isc, &active_mask);
 	}
@@ -1567,6 +1569,7 @@ static int get_top_gisa_isc(struct kvm *kvm, u64 isc_mask, u32 schid)
 struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 						    u64 isc_mask, u32 schid)
 {
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
 	struct kvm_s390_interrupt_info *inti, *tmp_inti;
 	int isc;
 
@@ -1584,7 +1587,7 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 	/* both types of interrupts present */
 	if (int_word_to_isc(inti->io.io_int_word) <= isc) {
 		/* classical IO int with higher priority */
-		gisa_set_ipm_gisc(kvm->arch.gisa, isc);
+		gisa_set_ipm_gisc(gi->origin, isc);
 		goto out;
 	}
 gisa_out:
@@ -1596,7 +1599,7 @@ struct kvm_s390_interrupt_info *kvm_s390_get_io_int(struct kvm *kvm,
 			kvm_s390_reinject_io_int(kvm, inti);
 		inti = tmp_inti;
 	} else
-		gisa_set_ipm_gisc(kvm->arch.gisa, isc);
+		gisa_set_ipm_gisc(gi->origin, isc);
 out:
 	return inti;
 }
@@ -1685,6 +1688,7 @@ static int __inject_float_mchk(struct kvm *kvm,
 
 static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 {
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
 	struct kvm_s390_float_interrupt *fi;
 	struct list_head *list;
 	int isc;
@@ -1692,9 +1696,9 @@ static int __inject_io(struct kvm *kvm, struct kvm_s390_interrupt_info *inti)
 	kvm->stat.inject_io++;
 	isc = int_word_to_isc(inti->io.io_int_word);
 
-	if (kvm->arch.gisa && 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(kvm->arch.gisa, isc);
+		gisa_set_ipm_gisc(gi->origin, isc);
 		kfree(inti);
 		return 0;
 	}
@@ -1752,7 +1756,8 @@ static void __floating_irq_kick(struct kvm *kvm, u64 type)
 		kvm_s390_set_cpuflags(dst_vcpu, CPUSTAT_STOP_INT);
 		break;
 	case KVM_S390_INT_IO_MIN...KVM_S390_INT_IO_MAX:
-		if (!(type & KVM_S390_INT_IO_AI_MASK && kvm->arch.gisa))
+		if (!(type & KVM_S390_INT_IO_AI_MASK &&
+		      kvm->arch.gisa_int.origin))
 			kvm_s390_set_cpuflags(dst_vcpu, CPUSTAT_IO_INT);
 		break;
 	default:
@@ -2002,6 +2007,7 @@ void kvm_s390_clear_float_irqs(struct kvm *kvm)
 
 static int get_all_floating_irqs(struct kvm *kvm, u8 __user *usrbuf, u64 len)
 {
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
 	struct kvm_s390_interrupt_info *inti;
 	struct kvm_s390_float_interrupt *fi;
 	struct kvm_s390_irq *buf;
@@ -2025,14 +2031,14 @@ static int get_all_floating_irqs(struct kvm *kvm, u8 __user *usrbuf, u64 len)
 
 	max_irqs = len / sizeof(struct kvm_s390_irq);
 
-	if (kvm->arch.gisa && gisa_get_ipm(kvm->arch.gisa)) {
+	if (gi->origin && gisa_get_ipm(gi->origin)) {
 		for (i = 0; i <= MAX_ISC; i++) {
 			if (n == max_irqs) {
 				/* signal userspace to try again */
 				ret = -ENOMEM;
 				goto out_nolock;
 			}
-			if (gisa_tac_ipm_gisc(kvm->arch.gisa, i)) {
+			if (gisa_tac_ipm_gisc(gi->origin, i)) {
 				irq = (struct kvm_s390_irq *) &buf[n];
 				irq->type = KVM_S390_INT_IO(1, 0, 0, 0);
 				irq->u.io.io_int_word = isc_to_int_word(i);
@@ -2884,25 +2890,27 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
 
 void kvm_s390_gisa_clear(struct kvm *kvm)
 {
-	if (!kvm->arch.gisa)
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+
+	if (!gi->origin)
 		return;
-	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);
+	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
+	gi->origin->next_alert = (u32)(u64)gi->origin;
+	VM_EVENT(kvm, 3, "gisa 0x%pK cleared", gi->origin);
 }
 
 void kvm_s390_gisa_init(struct kvm *kvm)
 {
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+
 	if (!css_general_characteristics.aiv)
 		return;
-	kvm->arch.gisa = &kvm->arch.sie_page2->gisa;
+	gi->origin = &kvm->arch.sie_page2->gisa;
 	kvm_s390_gisa_clear(kvm);
-	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", kvm->arch.gisa);
+	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }
 
 void kvm_s390_gisa_destroy(struct kvm *kvm)
 {
-	if (!kvm->arch.gisa)
-		return;
-	kvm->arch.gisa = NULL;
+	kvm->arch.gisa_int.origin = NULL;
 }
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 7f4bc58a53b9..4c855cb67699 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2812,7 +2812,7 @@ 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;
+	vcpu->arch.sie_block->gd = (u32)(u64)kvm->arch.gisa_int.origin;
 	if (vcpu->arch.sie_block->gd && sclp.has_gisaf)
 		vcpu->arch.sie_block->gd |= GISA_FORMAT1;
 	seqcount_init(&vcpu->arch.cputm_seqcount);
-- 
2.13.4

[PATCH v7 08/15] s390/cio: add function chsc_sgib()

[Michael Mueller]

This patch implements the Set Guest Information Block operation
to request association or disassociation of a Guest Information
Block (GIB) with the Adapter Interruption Facility. The operation
is required to receive GIB alert interrupts for guest adapters
in conjunction with AIV and GISA.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Sebastian Ott <sebott@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
---
 arch/s390/include/asm/cio.h |  1 +
 drivers/s390/cio/chsc.c     | 37 +++++++++++++++++++++++++++++++++++++
 drivers/s390/cio/chsc.h     |  1 +
 3 files changed, 39 insertions(+)

diff --git a/arch/s390/include/asm/cio.h b/arch/s390/include/asm/cio.h
index 225667652069..1727180e8ca1 100644
--- a/arch/s390/include/asm/cio.h
+++ b/arch/s390/include/asm/cio.h
@@ -331,5 +331,6 @@ extern void css_schedule_reprobe(void);
 /* Function from drivers/s390/cio/chsc.c */
 int chsc_sstpc(void *page, unsigned int op, u16 ctrl, u64 *clock_delta);
 int chsc_sstpi(void *page, void *result, size_t size);
+int chsc_sgib(u32 origin);
 
 #endif
diff --git a/drivers/s390/cio/chsc.c b/drivers/s390/cio/chsc.c
index a0baee25134c..4159c63a5fd2 100644
--- a/drivers/s390/cio/chsc.c
+++ b/drivers/s390/cio/chsc.c
@@ -1382,3 +1382,40 @@ int chsc_pnso_brinfo(struct subchannel_id schid,
 	return chsc_error_from_response(brinfo_area->response.code);
 }
 EXPORT_SYMBOL_GPL(chsc_pnso_brinfo);
+
+int chsc_sgib(u32 origin)
+{
+	struct {
+		struct chsc_header request;
+		u16 op;
+		u8  reserved01[2];
+		u8  reserved02:4;
+		u8  fmt:4;
+		u8  reserved03[7];
+		/* operation data area begin */
+		u8  reserved04[4];
+		u32 gib_origin;
+		u8  reserved05[10];
+		u8  aix;
+		u8  reserved06[4029];
+		struct chsc_header response;
+		u8  reserved07[4];
+	} *sgib_area;
+	int ret;
+
+	spin_lock_irq(&chsc_page_lock);
+	memset(chsc_page, 0, PAGE_SIZE);
+	sgib_area = chsc_page;
+	sgib_area->request.length = 0x0fe0;
+	sgib_area->request.code = 0x0021;
+	sgib_area->op = 0x1;
+	sgib_area->gib_origin = origin;
+
+	ret = chsc(sgib_area);
+	if (ret == 0)
+		ret = chsc_error_from_response(sgib_area->response.code);
+	spin_unlock_irq(&chsc_page_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(chsc_sgib);
diff --git a/drivers/s390/cio/chsc.h b/drivers/s390/cio/chsc.h
index 78aba8d94eec..e57d68e325a3 100644
--- a/drivers/s390/cio/chsc.h
+++ b/drivers/s390/cio/chsc.h
@@ -164,6 +164,7 @@ int chsc_get_channel_measurement_chars(struct channel_path *chp);
 int chsc_ssqd(struct subchannel_id schid, struct chsc_ssqd_area *ssqd);
 int chsc_sadc(struct subchannel_id schid, struct chsc_scssc_area *scssc,
 	      u64 summary_indicator_addr, u64 subchannel_indicator_addr);
+int chsc_sgib(u32 origin);
 int chsc_error_from_response(int response);
 
 int chsc_siosl(struct subchannel_id schid);
-- 
2.13.4

[PATCH v7 09/15] KVM: s390: add the GIB and its related life-cyle functions

[Michael Mueller]

The Guest Information Block (GIB) links the GISA of all guests
that have adapter interrupts pending. These interrupts cannot be
delivered because all vcpus of these guests are currently in WAIT
state or have masked the respective Interruption Sub Class (ISC).
If enabled, a GIB alert is issued on the host to schedule these
guests to run suitable vcpus to consume the pending interruptions.

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.

The GIB initialization and thus the activation of the related code
will be done in an upcoming patch of this series.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  9 +++++++++
 arch/s390/kvm/interrupt.c        | 43 ++++++++++++++++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.c         |  1 +
 arch/s390/kvm/kvm-s390.h         |  2 ++
 4 files changed, 55 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 0941571d34eb..397af0d33539 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -784,6 +784,15 @@ struct kvm_s390_gisa {
 	};
 };
 
+struct kvm_s390_gib {
+	u32 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.
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index ee91d1de0036..5efcd9e2cf8f 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -7,6 +7,9 @@
  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  */
 
+#define KMSG_COMPONENT "kvm-s390"
+#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
+
 #include <linux/interrupt.h>
 #include <linux/kvm_host.h>
 #include <linux/hrtimer.h>
@@ -31,6 +34,8 @@
 #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)
 {
@@ -2914,3 +2919,41 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
 {
 	kvm->arch.gisa_int.origin = NULL;
 }
+
+void kvm_s390_gib_destroy(void)
+{
+	if (!gib)
+		return;
+	chsc_sgib(0);
+	free_page((unsigned long)gib);
+	gib = NULL;
+}
+
+int kvm_s390_gib_init(u8 nisc)
+{
+	int rc = 0;
+
+	if (!css_general_characteristics.aiv) {
+		KVM_EVENT(3, "%s", "gib not initialized, no AIV facility");
+		goto out;
+	}
+
+	gib = (struct kvm_s390_gib *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!gib) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	gib->nisc = nisc;
+	if (chsc_sgib((u32)(u64)gib)) {
+		pr_err("Associating the GIB with the AIV facility failed\n");
+		free_page((unsigned long)gib);
+		gib = NULL;
+		rc = -EIO;
+		goto out;
+	}
+
+	KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
+out:
+	return rc;
+}
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4c855cb67699..118d4c0bbb8e 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -444,6 +444,7 @@ 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 72ef87799593..6d9448dbd052 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -381,6 +381,8 @@ 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);
+int 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);
-- 
2.13.4

[PATCH v7 10/15] KVM: s390: add kvm reference to struct sie_page2

[Michael Mueller]

Adding the kvm reference to struct sie_page2 will allow to
determine the kvm a given gisa belongs to:

  container_of(gisa, struct sie_page2, gisa)->kvm

This functionality will be required to process a gisa in
gib alert interruption context.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h | 3 ++-
 arch/s390/kvm/kvm-s390.c         | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 397af0d33539..7077762ab460 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -801,7 +801,8 @@ struct sie_page2 {
 	__u64 fac_list[S390_ARCH_FAC_LIST_SIZE_U64];	/* 0x0000 */
 	struct kvm_s390_crypto_cb crycb;		/* 0x0800 */
 	struct kvm_s390_gisa gisa;			/* 0x0900 */
-	u8 reserved920[0x1000 - 0x920];			/* 0x0920 */
+	struct kvm *kvm;				/* 0x0920 */
+	u8 reserved928[0x1000 - 0x928];			/* 0x0928 */
 };
 
 struct kvm_s390_vsie {
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 118d4c0bbb8e..67023d5656fd 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2210,6 +2210,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	if (!kvm->arch.sie_page2)
 		goto out_err;
 
+	kvm->arch.sie_page2->kvm = kvm;
 	kvm->arch.model.fac_list = kvm->arch.sie_page2->fac_list;
 
 	for (i = 0; i < kvm_s390_fac_size(); i++) {
-- 
2.13.4

[PATCH v7 11/15] KVM: s390: add functions to (un)register GISC with GISA

[Michael Mueller]

Add the Interruption Alert Mask (IAM) to the architecture specific
kvm struct. This mask in the GISA is used to define for which ISC
a GIB alert will be issued.

The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister()
are used to (un)register a GISC (guest ISC) with a virtual machine and
its GISA.

Upon successful completion, kvm_s390_gisc_register() returns the
ISC to be used for GIB alert interruptions. A negative return code
indicates an error during registration.

Theses functions will be used by other adapter types like AP and PCI to
request pass-through interruption support.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/kvm_host.h |  13 +++++
 arch/s390/kvm/interrupt.c        | 112 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 125 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 7077762ab460..2cfff617cb21 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -781,6 +781,9 @@ struct kvm_s390_gisa {
 			u8  reserved03[11];
 			u32 airq_count;
 		} g1;
+		struct {
+			u64 word[4];
+		} u64;
 	};
 };
 
@@ -813,8 +816,15 @@ struct kvm_s390_vsie {
 	struct page *pages[KVM_MAX_VCPUS];
 };
 
+struct kvm_s390_gisa_iam {
+	u8 mask;
+	spinlock_t ref_lock;
+	u32 ref_count[MAX_ISC + 1];
+};
+
 struct kvm_s390_gisa_interrupt {
 	struct kvm_s390_gisa *origin;
+	struct kvm_s390_gisa_iam alert;
 };
 
 struct kvm_arch{
@@ -885,6 +895,9 @@ void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
 extern int sie64a(struct kvm_s390_sie_block *, u64 *);
 extern char sie_exit;
 
+extern int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc);
+extern int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc);
+
 static inline void kvm_arch_hardware_disable(void) {}
 static inline void kvm_arch_check_processor_compat(void *rtn) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 5efcd9e2cf8f..f37dfb01c63c 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -222,6 +222,33 @@ static inline u8 int_word_to_isc(u32 int_word)
  */
 #define IPM_BIT_OFFSET (offsetof(struct kvm_s390_gisa, ipm) * BITS_PER_BYTE)
 
+/**
+ * gisa_set_iam - change the GISA interruption alert mask
+ *
+ * @gisa: gisa to operate on
+ * @iam: new IAM value to use
+ *
+ * Change the IAM atomically with the next alert address and the IPM
+ * of the GISA if the GISA is not part of the GIB alert list. All three
+ * fields are located in the first long word of the GISA.
+ *
+ * Returns: 0 on success
+ *          -EBUSY in case the gisa is part of the alert list
+ */
+static inline int gisa_set_iam(struct kvm_s390_gisa *gisa, u8 iam)
+{
+	u64 word, _word;
+
+	do {
+		word = READ_ONCE(gisa->u64.word[0]);
+		if ((u64)gisa != word >> 32)
+			return -EBUSY;
+		_word = (word & ~0xffUL) | iam;
+	} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
+
+	return 0;
+}
+
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
 	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
@@ -2911,6 +2938,8 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	if (!css_general_characteristics.aiv)
 		return;
 	gi->origin = &kvm->arch.sie_page2->gisa;
+	gi->alert.mask = 0;
+	spin_lock_init(&gi->alert.ref_lock);
 	kvm_s390_gisa_clear(kvm);
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }
@@ -2920,6 +2949,89 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
 	kvm->arch.gisa_int.origin = NULL;
 }
 
+/**
+ * kvm_s390_gisc_register - register a guest ISC
+ *
+ * @kvm:  the kernel vm to work with
+ * @gisc: the guest interruption sub class to register
+ *
+ * The function extends the vm specific alert mask to use.
+ * The effectve IAM mask in the GISA is updated as well
+ * in case the GISA is not part of the GIB alert list.
+ * It will be updated latest when the IAM gets restored
+ * by gisa_get_ipm_or_restore_iam().
+ *
+ * Returns: the nonspecific ISC (NISC) the gib alert mechanism
+ *          has registered with the channel subsystem.
+ *          -ENODEV in case the vm uses no GISA
+ *          -ERANGE in case the guest ISC is invalid
+ */
+int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
+{
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+
+	if (!gi->origin)
+		return -ENODEV;
+	if (gisc > MAX_ISC)
+		return -ERANGE;
+
+	spin_lock(&gi->alert.ref_lock);
+	gi->alert.ref_count[gisc]++;
+	if (gi->alert.ref_count[gisc] == 1) {
+		gi->alert.mask |= 0x80 >> gisc;
+		gisa_set_iam(gi->origin, gi->alert.mask);
+	}
+	spin_unlock(&gi->alert.ref_lock);
+
+	return gib->nisc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_register);
+
+/**
+ * kvm_s390_gisc_unregister - unregister a guest ISC
+ *
+ * @kvm:  the kernel vm to work with
+ * @gisc: the guest interruption sub class to register
+ *
+ * The function reduces the vm specific alert mask to use.
+ * The effectve IAM mask in the GISA is updated as well
+ * in case the GISA is not part of the GIB alert list.
+ * It will be updated latest when the IAM gets restored
+ * by gisa_get_ipm_or_restore_iam().
+ *
+ * Returns: the nonspecific ISC (NISC) the gib alert mechanism
+ *          has registered with the channel subsystem.
+ *          -ENODEV in case the vm uses no GISA
+ *          -ERANGE in case the guest ISC is invalid
+ *          -EINVAL in case the guest ISC is not registered
+ */
+int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
+{
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+	int rc = 0;
+
+	if (!gi->origin)
+		return -ENODEV;
+	if (gisc > MAX_ISC)
+		return -ERANGE;
+
+	spin_lock(&gi->alert.ref_lock);
+	if (gi->alert.ref_count[gisc] == 0) {
+		rc = -EINVAL;
+		goto out;
+	}
+	gi->alert.ref_count[gisc]--;
+	if (gi->alert.ref_count[gisc] == 0) {
+		gi->alert.mask &= ~(0x80 >> gisc);
+		gisa_set_iam(gi->origin, gi->alert.mask);
+	}
+out:
+	spin_unlock(&gi->alert.ref_lock);
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
+
 void kvm_s390_gib_destroy(void)
 {
 	if (!gib)
-- 
2.13.4

[PATCH v7 12/15] KVM: s390: kvm_s390_gisa_clear() now clears the IPM only

[Michael Mueller]

Function kvm_s390_gisa_clear() now clears the Interruption
Pending Mask of the GISA asap. If the GISA is in the alert
list at this time it stays in the list but is removed by
process_gib_alert_list().

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index f37dfb01c63c..341664b94491 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -249,6 +249,25 @@ static inline int gisa_set_iam(struct kvm_s390_gisa *gisa, u8 iam)
 	return 0;
 }
 
+/**
+ * gisa_clear_ipm - clear the GISA interruption pending mask
+ *
+ * @gisa: gisa to operate on
+ *
+ * Clear the IPM atomically with the next alert address and the IAM
+ * of the GISA unconditionally. All three fields are located in the
+ * first long word of the GISA.
+ */
+static inline void gisa_clear_ipm(struct kvm_s390_gisa *gisa)
+{
+	u64 word, _word;
+
+	do {
+		word = READ_ONCE(gisa->u64.word[0]);
+		_word = word & ~(0xffUL << 24);
+	} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
+}
+
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
 	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
@@ -2926,8 +2945,7 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
 
 	if (!gi->origin)
 		return;
-	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
-	gi->origin->next_alert = (u32)(u64)gi->origin;
+	gisa_clear_ipm(gi->origin);
 	VM_EVENT(kvm, 3, "gisa 0x%pK cleared", gi->origin);
 }
 
@@ -2940,7 +2958,8 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	gi->origin = &kvm->arch.sie_page2->gisa;
 	gi->alert.mask = 0;
 	spin_lock_init(&gi->alert.ref_lock);
-	kvm_s390_gisa_clear(kvm);
+	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
+	gi->origin->next_alert = (u32)(u64)gi->origin;
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }
 
-- 
2.13.4

[PATCH v7 13/15] KVM: s390: add gib_alert_irq_handler()

[Michael Mueller]

The patch implements a handler for GIB alert interruptions
on the host. Its task is to alert guests that interrupts are
pending for them.

A GIB alert interrupt statistic counter is added as well:

$ cat /proc/interrupts
          CPU0       CPU1
  ...
  GAL:      23         37   [I/O] GIB Alert
  ...

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/include/asm/irq.h      |   1 +
 arch/s390/include/asm/isc.h      |   1 +
 arch/s390/include/asm/kvm_host.h |   3 +
 arch/s390/kernel/irq.c           |   1 +
 arch/s390/kvm/interrupt.c        | 169 ++++++++++++++++++++++++++++++++++++++-
 arch/s390/kvm/kvm-s390.c         |   2 +
 6 files changed, 175 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/irq.h b/arch/s390/include/asm/irq.h
index 2f7f27e5493f..afaf5e3c57fd 100644
--- a/arch/s390/include/asm/irq.h
+++ b/arch/s390/include/asm/irq.h
@@ -62,6 +62,7 @@ enum interruption_class {
 	IRQIO_MSI,
 	IRQIO_VIR,
 	IRQIO_VAI,
+	IRQIO_GAL,
 	NMI_NMI,
 	CPU_RST,
 	NR_ARCH_IRQS
diff --git a/arch/s390/include/asm/isc.h b/arch/s390/include/asm/isc.h
index 6cb9e2ed05b6..b2cc1ec78d06 100644
--- a/arch/s390/include/asm/isc.h
+++ b/arch/s390/include/asm/isc.h
@@ -21,6 +21,7 @@
 /* Adapter interrupts. */
 #define QDIO_AIRQ_ISC IO_SCH_ISC	/* I/O subchannel in qdio mode */
 #define PCI_ISC 2			/* PCI I/O subchannels */
+#define GAL_ISC 5			/* GIB alert */
 #define AP_ISC 6			/* adjunct processor (crypto) devices */
 
 /* Functions for registration of I/O interruption subclasses */
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 2cfff617cb21..c5f51566ecd6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -825,6 +825,9 @@ struct kvm_s390_gisa_iam {
 struct kvm_s390_gisa_interrupt {
 	struct kvm_s390_gisa *origin;
 	struct kvm_s390_gisa_iam alert;
+	struct hrtimer timer;
+	u64 expires;
+	DECLARE_BITMAP(kicked_mask, KVM_MAX_VCPUS);
 };
 
 struct kvm_arch{
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index 0e8d68bac82c..0cd5a5f96729 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -88,6 +88,7 @@ static const struct irq_class irqclass_sub_desc[] = {
 	{.irq = IRQIO_MSI,  .name = "MSI", .desc = "[I/O] MSI Interrupt" },
 	{.irq = IRQIO_VIR,  .name = "VIR", .desc = "[I/O] Virtual I/O Devices"},
 	{.irq = IRQIO_VAI,  .name = "VAI", .desc = "[I/O] Virtual I/O Devices AI"},
+	{.irq = IRQIO_GAL,  .name = "GAL", .desc = "[I/O] GIB Alert"},
 	{.irq = NMI_NMI,    .name = "NMI", .desc = "[NMI] Machine Check"},
 	{.irq = CPU_RST,    .name = "RST", .desc = "[CPU] CPU Restart"},
 };
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 341664b94491..d322400ca587 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -26,6 +26,7 @@
 #include <asm/gmap.h>
 #include <asm/switch_to.h>
 #include <asm/nmi.h>
+#include <asm/airq.h>
 #include "kvm-s390.h"
 #include "gaccess.h"
 #include "trace-s390.h"
@@ -268,6 +269,38 @@ static inline void gisa_clear_ipm(struct kvm_s390_gisa *gisa)
 	} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
 }
 
+/**
+ * gisa_get_ipm_or_restore_iam - return IPM or restore GISA IAM
+ *
+ * @gi: gisa interrupt struct to work on
+ *
+ * Atomically restores the interruption alert mask if none of the
+ * relevant ISCs are pending and return the IPM.
+ *
+ * Returns: the relevant pending ISCs
+ */
+static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
+{
+	u8 pending_mask, alert_mask;
+	u64 word, _word;
+
+	do {
+		word = READ_ONCE(gi->origin->u64.word[0]);
+		alert_mask = READ_ONCE(gi->alert.mask);
+		pending_mask = (u8)(word >> 24) & alert_mask;
+		if (pending_mask)
+			return pending_mask;
+		_word = (word & ~0xffUL) | alert_mask;
+	} while (cmpxchg(&gi->origin->u64.word[0], word, _word) != word);
+
+	return 0;
+}
+
+static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
+{
+	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
+}
+
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
 	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
@@ -1141,6 +1174,7 @@ static u64 __calculate_sltime(struct kvm_vcpu *vcpu)
 
 int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
 {
+	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
 	u64 sltime;
 
 	vcpu->stat.exit_wait_state++;
@@ -1154,6 +1188,11 @@ int kvm_s390_handle_wait(struct kvm_vcpu *vcpu)
 		return -EOPNOTSUPP; /* disabled wait */
 	}
 
+	if (gi->origin &&
+	    (gisa_get_ipm_or_restore_iam(gi) &
+	     vcpu->arch.sie_block->gcr[6] >> 24))
+		return 0;
+
 	if (!ckc_interrupts_enabled(vcpu) &&
 	    !cpu_timer_interrupts_enabled(vcpu)) {
 		VCPU_EVENT(vcpu, 3, "%s", "enabled wait w/o timer");
@@ -2939,6 +2978,93 @@ int kvm_s390_get_irq_state(struct kvm_vcpu *vcpu, __u8 __user *buf, int len)
 	return n;
 }
 
+static void __airqs_kick_single_vcpu(struct kvm *kvm, u8 deliverable_mask)
+{
+	int vcpu_id, online_vcpus = atomic_read(&kvm->online_vcpus);
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+	struct kvm_vcpu *vcpu;
+
+	for_each_set_bit(vcpu_id, kvm->arch.idle_mask, online_vcpus) {
+		vcpu = kvm_get_vcpu(kvm, vcpu_id);
+		if (psw_ioint_disabled(vcpu))
+			continue;
+		deliverable_mask &= (u8)(vcpu->arch.sie_block->gcr[6] >> 24);
+		if (deliverable_mask) {
+			/* lately kicked but not yet running */
+			if (test_and_set_bit(vcpu_id, gi->kicked_mask))
+				return;
+			kvm_s390_vcpu_wakeup(vcpu);
+			return;
+		}
+	}
+}
+
+static enum hrtimer_restart gisa_vcpu_kicker(struct hrtimer *timer)
+{
+	struct kvm_s390_gisa_interrupt *gi =
+		container_of(timer, struct kvm_s390_gisa_interrupt, timer);
+	struct kvm *kvm =
+		container_of(gi->origin, struct sie_page2, gisa)->kvm;
+	u8 pending_mask;
+
+	pending_mask = gisa_get_ipm_or_restore_iam(gi);
+	if (pending_mask) {
+		__airqs_kick_single_vcpu(kvm, pending_mask);
+		hrtimer_forward_now(timer, ns_to_ktime(gi->expires));
+		return HRTIMER_RESTART;
+	};
+
+	return HRTIMER_NORESTART;
+}
+
+#define NULL_GISA_ADDR 0x00000000UL
+#define NONE_GISA_ADDR 0x00000001UL
+#define GISA_ADDR_MASK 0xfffff000UL
+
+static void process_gib_alert_list(void)
+{
+	struct kvm_s390_gisa_interrupt *gi;
+	struct kvm_s390_gisa *gisa;
+	struct kvm *kvm;
+	u32 final, origin = 0UL;
+
+	do {
+		/*
+		 * If the NONE_GISA_ADDR is still stored in the alert list
+		 * origin, we will leave the outer loop. No further GISA has
+		 * been added to the alert list by millicode while processing
+		 * the current alert list.
+		 */
+		final = (origin & NONE_GISA_ADDR);
+		/*
+		 * Cut off the alert list and store the NONE_GISA_ADDR in the
+		 * alert list origin to avoid further GAL interruptions.
+		 * A new alert list can be build up by millicode in parallel
+		 * for guests not in the yet cut-off alert list. When in the
+		 * final loop, store the NULL_GISA_ADDR instead. This will re-
+		 * enable GAL interruptions on the host again.
+		 */
+		origin = xchg(&gib->alert_list_origin,
+			      (!final) ? NONE_GISA_ADDR : NULL_GISA_ADDR);
+		/*
+		 * Loop through the just cut-off alert list and start the
+		 * gisa timers to kick idle vcpus to consume the pending
+		 * interruptions asap.
+		 */
+		while (origin & GISA_ADDR_MASK) {
+			gisa = (struct kvm_s390_gisa *)(u64)origin;
+			origin = gisa->next_alert;
+			gisa->next_alert = (u32)(u64)gisa;
+			kvm = container_of(gisa, struct sie_page2, gisa)->kvm;
+			gi = &kvm->arch.gisa_int;
+			if (hrtimer_active(&gi->timer))
+				hrtimer_cancel(&gi->timer);
+			hrtimer_start(&gi->timer, 0, HRTIMER_MODE_REL);
+		}
+	} while (!final);
+
+}
+
 void kvm_s390_gisa_clear(struct kvm *kvm)
 {
 	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
@@ -2958,6 +3084,9 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	gi->origin = &kvm->arch.sie_page2->gisa;
 	gi->alert.mask = 0;
 	spin_lock_init(&gi->alert.ref_lock);
+	gi->expires = 50 * 1000; /* 50 usec */
+	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+	gi->timer.function = gisa_vcpu_kicker;
 	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
 	gi->origin->next_alert = (u32)(u64)gi->origin;
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
@@ -2965,7 +3094,17 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 
 void kvm_s390_gisa_destroy(struct kvm *kvm)
 {
-	kvm->arch.gisa_int.origin = NULL;
+	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
+
+	if (!gi->origin)
+		return;
+	if (gi->alert.mask)
+		KVM_EVENT(3, "vm 0x%pK has unexpected iam 0x%02x",
+			  kvm, gi->alert.mask);
+	while (gisa_in_alert_list(gi->origin))
+		cpu_relax();
+	hrtimer_cancel(&gi->timer);
+	gi->origin = NULL;
 }
 
 /**
@@ -3051,11 +3190,23 @@ int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
 }
 EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
 
+static void gib_alert_irq_handler(struct airq_struct *airq)
+{
+	inc_irq_stat(IRQIO_GAL);
+	process_gib_alert_list();
+}
+
+static struct airq_struct gib_alert_irq = {
+	.handler = gib_alert_irq_handler,
+	.lsi_ptr = &gib_alert_irq.lsi_mask,
+};
+
 void kvm_s390_gib_destroy(void)
 {
 	if (!gib)
 		return;
 	chsc_sgib(0);
+	unregister_adapter_interrupt(&gib_alert_irq);
 	free_page((unsigned long)gib);
 	gib = NULL;
 }
@@ -3075,16 +3226,30 @@ int kvm_s390_gib_init(u8 nisc)
 		goto out;
 	}
 
+	gib_alert_irq.isc = nisc;
+	if (register_adapter_interrupt(&gib_alert_irq)) {
+		pr_err("Registering the GIB alert interruption handler failed\n");
+		rc = -EIO;
+		goto out_free_gib;
+	}
+
 	gib->nisc = nisc;
 	if (chsc_sgib((u32)(u64)gib)) {
 		pr_err("Associating the GIB with the AIV facility failed\n");
 		free_page((unsigned long)gib);
 		gib = NULL;
 		rc = -EIO;
-		goto out;
+		goto out_unreg_gal;
 	}
 
 	KVM_EVENT(3, "gib 0x%pK (nisc=%d) initialized", gib, gib->nisc);
+	goto out;
+
+out_unreg_gal:
+	unregister_adapter_interrupt(&gib_alert_irq);
+out_free_gib:
+	free_page((unsigned long)gib);
+	gib = NULL;
 out:
 	return rc;
 }
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 67023d5656fd..0e6ba4d17207 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -3460,6 +3460,8 @@ static int vcpu_pre_run(struct kvm_vcpu *vcpu)
 		kvm_s390_patch_guest_per_regs(vcpu);
 	}
 
+	clear_bit(vcpu->vcpu_id, vcpu->kvm->arch.gisa_int.kicked_mask);
+
 	vcpu->arch.sie_block->icptcode = 0;
 	cpuflags = atomic_read(&vcpu->arch.sie_block->cpuflags);
 	VCPU_EVENT(vcpu, 6, "entering sie flags %x", cpuflags);
-- 
2.13.4

[PATCH v7 14/15] KVM: s390: start using the GIB

[Michael Mueller]

By initializing the GIB, it will be used by the kvm host.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 0e6ba4d17207..dcf6d62b4e80 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -435,8 +435,15 @@ int kvm_arch_init(void *opaque)
 		pr_err("Failed to register FLIC rc=%d\n", rc);
 		goto out_debug_unreg;
 	}
+
+	rc = kvm_s390_gib_init(GAL_ISC);
+	if (rc)
+		goto out_gib_destroy;
+
 	return 0;
 
+out_gib_destroy:
+	kvm_s390_gib_destroy();
 out_debug_unreg:
 	debug_unregister(kvm_s390_dbf);
 	return rc;
-- 
2.13.4

[PATCH v7 15/15] KVM: s390: fix possible null pointer dereference in pending_irqs()

[Michael Mueller]

Assure a GISA is in use before accessing the IPM to avoid a
null pointer dereference issue.

Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
Reported-by: Halil Pasic <pasic@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index d322400ca587..660ec87b6e60 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -329,9 +329,13 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
 
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
-	return pending_irqs_no_gisa(vcpu) |
-		gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
-			IRQ_PEND_IO_ISC_7;
+	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
+	unsigned long pending_mask;
+
+	pending_mask = pending_irqs_no_gisa(vcpu);
+	if (gi->origin)
+		pending_mask |= gisa_get_ipm(gi->origin) << IRQ_PEND_IO_ISC_7;
+	return pending_mask;
 }
 
 static inline int isc_to_irq_type(unsigned long isc)
-- 
2.13.4

[PATCH v7 15/15] KVM: s390: test for non NULL gisa origin in pending_irqs()

[Michael Mueller]

Assure a GISA is in use before accessing the IPM to avoid
a NULL pointer de-referencing issue.

Reported-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
---
 arch/s390/kvm/interrupt.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index d322400ca587..660ec87b6e60 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -329,9 +329,13 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
 
 static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
 {
-	return pending_irqs_no_gisa(vcpu) |
-		gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
-			IRQ_PEND_IO_ISC_7;
+	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
+	unsigned long pending_mask;
+
+	pending_mask = pending_irqs_no_gisa(vcpu);
+	if (gi->origin)
+		pending_mask |= gisa_get_ipm(gi->origin) << IRQ_PEND_IO_ISC_7;
+	return pending_mask;
 }
 
 static inline int isc_to_irq_type(unsigned long isc)
-- 
2.13.4

Re: [PATCH v7 15/15] KVM: s390: test for non NULL gisa origin in pending_irqs()

[Michael Mueller]

Ignore this patch please, it has the wrong commit message.


The following is the right patch:

"KVM: s390: fix possible null pointer dereference in pending_irqs()"


On 31.01.19 09:52, Michael Mueller wrote:
> Assure a GISA is in use before accessing the IPM to avoid
> a NULL pointer de-referencing issue.
>
> Reported-by: Halil Pasic <pasic@linux.ibm.com>
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> ---
>   arch/s390/kvm/interrupt.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index d322400ca587..660ec87b6e60 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -329,9 +329,13 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
>   
>   static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
>   {
> -	return pending_irqs_no_gisa(vcpu) |
> -		gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
> -			IRQ_PEND_IO_ISC_7;
> +	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
> +	unsigned long pending_mask;
> +
> +	pending_mask = pending_irqs_no_gisa(vcpu);
> +	if (gi->origin)
> +		pending_mask |= gisa_get_ipm(gi->origin) << IRQ_PEND_IO_ISC_7;
> +	return pending_mask;
>   }
>   
>   static inline int isc_to_irq_type(unsigned long isc)

-- 
Mit freundlichen Grüßen / Kind regards
Michael Müller

IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
Registergericht: Amtsgericht Stuttgart, HRB 243294

Re: [PATCH v7 03/15] KVM: s390: move bitmap idle_mask into arch struct top level

[Halil Pasic]

On Thu, 31 Jan 2019 09:52:34 +0100
Michael Mueller <mimu@linux.ibm.com> wrote:

> The vcpu idle_mask state is used by but not specific
> to the emulated floating interruptions. The state is
> relevant to gisa related interruptions as well.
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Acked-by: Halil Pasic <pasic@linux.ibm.com>

Re: [PATCH v7 12/15] KVM: s390: kvm_s390_gisa_clear() now clears the IPM only

[Halil Pasic]

On Thu, 31 Jan 2019 09:52:43 +0100
Michael Mueller <mimu@linux.ibm.com> wrote:

> Function kvm_s390_gisa_clear() now clears the Interruption
> Pending Mask of the GISA asap. If the GISA is in the alert
> list at this time it stays in the list but is removed by
> process_gib_alert_list().
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index f37dfb01c63c..341664b94491 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -249,6 +249,25 @@ static inline int gisa_set_iam(struct kvm_s390_gisa *gisa, u8 iam)
>  	return 0;
>  }
>  
> +/**
> + * gisa_clear_ipm - clear the GISA interruption pending mask
> + *
> + * @gisa: gisa to operate on
> + *
> + * Clear the IPM atomically with the next alert address and the IAM
> + * of the GISA unconditionally. All three fields are located in the
> + * first long word of the GISA.
> + */
> +static inline void gisa_clear_ipm(struct kvm_s390_gisa *gisa)
> +{
> +	u64 word, _word;
> +
> +	do {
> +		word = READ_ONCE(gisa->u64.word[0]);
> +		_word = word & ~(0xffUL << 24);
> +	} while (cmpxchg(&gisa->u64.word[0], word, _word) != word);
> +}
> +
>  static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
>  {
>  	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
> @@ -2926,8 +2945,7 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
>  
>  	if (!gi->origin)
>  		return;
> -	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
> -	gi->origin->next_alert = (u32)(u64)gi->origin;
> +	gisa_clear_ipm(gi->origin);
>  	VM_EVENT(kvm, 3, "gisa 0x%pK cleared", gi->origin);
>  }

I'm a bit confused. Now all kvm_s390_gisa_clear() does to the gisa is
gisa_clear_ipm(). The only usage I see is triggered by
KVM_DEV_FLIC_CLEAR_IRQS. And in that context this seems appropriate.

However gisa can hold other stuff than the ipm, and in that sense
the name kvm_s390_gisa_clear() may be misleading. I ask myself
questions like who would need to reset simm and nimm on system
reset. At the moment we don't use these AFAICT, so I guess it does not
matter.

Thus not a showstopper to me:

Acked-by: Halil Pasic <pasic@linux.ibm.com>


>  
> @@ -2940,7 +2958,8 @@ void kvm_s390_gisa_init(struct kvm *kvm)
>  	gi->origin = &kvm->arch.sie_page2->gisa;
>  	gi->alert.mask = 0;
>  	spin_lock_init(&gi->alert.ref_lock);
> -	kvm_s390_gisa_clear(kvm);
> +	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
> +	gi->origin->next_alert = (u32)(u64)gi->origin;
>  	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
>  }
>  

Re: [PATCH v7 11/15] KVM: s390: add functions to (un)register GISC with GISA

[Cornelia Huck]

On Thu, 31 Jan 2019 09:52:42 +0100
Michael Mueller <mimu@linux.ibm.com> wrote:

> Add the Interruption Alert Mask (IAM) to the architecture specific
> kvm struct. This mask in the GISA is used to define for which ISC
> a GIB alert will be issued.
> 
> The functions kvm_s390_gisc_register() and kvm_s390_gisc_unregister()
> are used to (un)register a GISC (guest ISC) with a virtual machine and
> its GISA.
> 
> Upon successful completion, kvm_s390_gisc_register() returns the
> ISC to be used for GIB alert interruptions. A negative return code
> indicates an error during registration.
> 
> Theses functions will be used by other adapter types like AP and PCI to
> request pass-through interruption support.
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Acked-by: Pierre Morel <pmorel@linux.ibm.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>  arch/s390/include/asm/kvm_host.h |  13 +++++
>  arch/s390/kvm/interrupt.c        | 112 +++++++++++++++++++++++++++++++++++++++
>  2 files changed, 125 insertions(+)

> +/**
> + * kvm_s390_gisc_register - register a guest ISC
> + *
> + * @kvm:  the kernel vm to work with
> + * @gisc: the guest interruption sub class to register
> + *
> + * The function extends the vm specific alert mask to use.
> + * The effectve IAM mask in the GISA is updated as well

Typo: s/effectve/effective/

> + * in case the GISA is not part of the GIB alert list.
> + * It will be updated latest when the IAM gets restored
> + * by gisa_get_ipm_or_restore_iam().
> + *
> + * Returns: the nonspecific ISC (NISC) the gib alert mechanism
> + *          has registered with the channel subsystem.
> + *          -ENODEV in case the vm uses no GISA
> + *          -ERANGE in case the guest ISC is invalid
> + */
> +int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
> +{
> +	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
> +
> +	if (!gi->origin)
> +		return -ENODEV;
> +	if (gisc > MAX_ISC)
> +		return -ERANGE;
> +
> +	spin_lock(&gi->alert.ref_lock);
> +	gi->alert.ref_count[gisc]++;
> +	if (gi->alert.ref_count[gisc] == 1) {
> +		gi->alert.mask |= 0x80 >> gisc;
> +		gisa_set_iam(gi->origin, gi->alert.mask);
> +	}
> +	spin_unlock(&gi->alert.ref_lock);
> +
> +	return gib->nisc;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_gisc_register);
> +
> +/**
> + * kvm_s390_gisc_unregister - unregister a guest ISC
> + *
> + * @kvm:  the kernel vm to work with
> + * @gisc: the guest interruption sub class to register
> + *
> + * The function reduces the vm specific alert mask to use.
> + * The effectve IAM mask in the GISA is updated as well

Same here.

> + * in case the GISA is not part of the GIB alert list.
> + * It will be updated latest when the IAM gets restored
> + * by gisa_get_ipm_or_restore_iam().
> + *
> + * Returns: the nonspecific ISC (NISC) the gib alert mechanism
> + *          has registered with the channel subsystem.
> + *          -ENODEV in case the vm uses no GISA
> + *          -ERANGE in case the guest ISC is invalid
> + *          -EINVAL in case the guest ISC is not registered
> + */
> +int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc)
> +{
> +	struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
> +	int rc = 0;
> +
> +	if (!gi->origin)
> +		return -ENODEV;
> +	if (gisc > MAX_ISC)
> +		return -ERANGE;
> +
> +	spin_lock(&gi->alert.ref_lock);
> +	if (gi->alert.ref_count[gisc] == 0) {
> +		rc = -EINVAL;
> +		goto out;
> +	}
> +	gi->alert.ref_count[gisc]--;
> +	if (gi->alert.ref_count[gisc] == 0) {
> +		gi->alert.mask &= ~(0x80 >> gisc);
> +		gisa_set_iam(gi->origin, gi->alert.mask);
> +	}
> +out:
> +	spin_unlock(&gi->alert.ref_lock);
> +
> +	return rc;
> +}
> +EXPORT_SYMBOL_GPL(kvm_s390_gisc_unregister);
> +
>  void kvm_s390_gib_destroy(void)
>  {
>  	if (!gib)

Otherwise, looks good AFAICS.

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

Re: [PATCH v7 15/15] KVM: s390: fix possible null pointer dereference in pending_irqs()

[Cornelia Huck]

On Thu, 31 Jan 2019 09:52:46 +0100
Michael Mueller <mimu@linux.ibm.com> wrote:

> Assure a GISA is in use before accessing the IPM to avoid a
> null pointer dereference issue.

This series can hopefully make it into the next merge window;
otherwise, queuing a patch fixing up the original code would be good.

> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Reported-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>  arch/s390/kvm/interrupt.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)

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

Re: [PATCH v7 15/15] KVM: s390: fix possible null pointer dereference in pending_irqs()

[Pierre Morel]

On 31/01/2019 09:52, Michael Mueller wrote:
> Assure a GISA is in use before accessing the IPM to avoid a
> null pointer dereference issue.
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Reported-by: Halil Pasic <pasic@linux.ibm.com>
> ---
>   arch/s390/kvm/interrupt.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
> index d322400ca587..660ec87b6e60 100644
> --- a/arch/s390/kvm/interrupt.c
> +++ b/arch/s390/kvm/interrupt.c
> @@ -329,9 +329,13 @@ static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
>   
>   static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
>   {
> -	return pending_irqs_no_gisa(vcpu) |
> -		gisa_get_ipm(vcpu->kvm->arch.gisa_int.origin) <<
> -			IRQ_PEND_IO_ISC_7;
> +	struct kvm_s390_gisa_interrupt *gi = &vcpu->kvm->arch.gisa_int;
> +	unsigned long pending_mask;
> +
> +	pending_mask = pending_irqs_no_gisa(vcpu);
> +	if (gi->origin)
> +		pending_mask |= gisa_get_ipm(gi->origin) << IRQ_PEND_IO_ISC_7;
> +	return pending_mask;
>   }
>   
>   static inline int isc_to_irq_type(unsigned long isc)
> 
Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>


-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

Re: [PATCH v7 15/15] KVM: s390: fix possible null pointer dereference in pending_irqs()

[Christian Borntraeger]

On 31.01.2019 18:47, Cornelia Huck wrote:
> On Thu, 31 Jan 2019 09:52:46 +0100
> Michael Mueller <mimu@linux.ibm.com> wrote:
> 
>> Assure a GISA is in use before accessing the IPM to avoid a
>> null pointer dereference issue.
> 
> This series can hopefully make it into the next merge window;
> otherwise, queuing a patch fixing up the original code would be good.


Yes, I plan to apply this series today.
> 
>>
>> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
>> Reported-by: Halil Pasic <pasic@linux.ibm.com>
>> ---
>>  arch/s390/kvm/interrupt.c | 10 +++++++---
>>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> 

Re: [PATCH v7 12/15] KVM: s390: kvm_s390_gisa_clear() now clears the IPM only

[Pierre Morel]

On 31/01/2019 09:52, Michael Mueller wrote:
> Function kvm_s390_gisa_clear() now clears the Interruption
> Pending Mask of the GISA asap. If the GISA is in the alert
> list at this time it stays in the list but is removed by
> process_gib_alert_list().
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>


I would have written "will be removed by ...." however

Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>

-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

Re: [PATCH v7 13/15] KVM: s390: add gib_alert_irq_handler()

[Pierre Morel]

On 31/01/2019 09:52, Michael Mueller wrote:
> The patch implements a handler for GIB alert interruptions
> on the host. Its task is to alert guests that interrupts are
> pending for them.
> 
> A GIB alert interrupt statistic counter is added as well:
> 
> $ cat /proc/interrupts
>            CPU0       CPU1
>    ...
>    GAL:      23         37   [I/O] GIB Alert
>    ...
> 
> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
> Acked-by: Halil Pasic <pasic@linux.ibm.com>
> ---

The only thing that bother me is the short timer's expiration value.
But it is optimization and it is working for me so.

Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>


-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany

Re: [PATCH v7 13/15] KVM: s390: add gib_alert_irq_handler()

[Michael Mueller]

On 05.02.19 12:38, Pierre Morel wrote:
> On 31/01/2019 09:52, Michael Mueller wrote:
>> The patch implements a handler for GIB alert interruptions
>> on the host. Its task is to alert guests that interrupts are
>> pending for them.
>>
>> A GIB alert interrupt statistic counter is added as well:
>>
>> $ cat /proc/interrupts
>>            CPU0       CPU1
>>    ...
>>    GAL:      23         37   [I/O] GIB Alert
>>    ...
>>
>> Signed-off-by: Michael Mueller <mimu@linux.ibm.com>
>> Acked-by: Halil Pasic <pasic@linux.ibm.com>
>> ---
> 
> The only thing that bother me is the short timer's expiration value.
> But it is optimization and it is working for me so.
> 
> Reviewed-by: Pierre Morel<pmorel@linux.ibm.com>


Thanks, Pierre.

For completion I want to add that one sees roughly 1 timer
restart per vcpu that gets kicked in my test scenario with
12 AP IRQ guests. The guests have 4 x 1, 4 x 4 and  4 x 8 vcpus
backed by 8 IFLs. Furthermore the 12 guests share 4 CEX5C cards
each configured with 3 AP queues. On the guest runs a single
threaded AP driver that performs RSA decryptions with CRT private
keys with a short 512 bit length to get many ops/s. That
run has no additional cpu load.

./run_ap_load.sh 12
[1] 12:53:09 [SUCCESS] root@ap04
[2] 12:53:09 [SUCCESS] root@ap08
[3] 12:53:10 [SUCCESS] root@ap02
[4] 12:53:10 [SUCCESS] root@ap03
[5] 12:53:10 [SUCCESS] root@ap01
[6] 12:53:10 [SUCCESS] root@ap12
[7] 12:53:10 [SUCCESS] root@ap06
[8] 12:53:10 [SUCCESS] root@ap05
[9] 12:53:10 [SUCCESS] root@ap07
[10] 12:53:10 [SUCCESS] root@ap10
[11] 12:53:10 [SUCCESS] root@ap09
[12] 12:53:10 [SUCCESS] root@ap11
KVM guests:          12
ica_perf threads:    1
stress cpu threads:  0
stress io threads:   0
expected  AP IRQs:   600048
observed  AP IRQs:   600048
observed VAI IRQs:   1311
observed GAL IRQs:   575505


__gal_stats_ipm_dirty = 613762
__gal_stats_timer_active = 0
__gal_stats_timer_no_restart = 600048
__gal_stats_timer_not_active = 600048
__gal_stats_timer_restart = 613762
__gal_stats_vcpus_kicked = 599688


The counters are placed as follows:

@@ -2998,6 +2999,7 @@ static void __airqs_kick_single_vcpu(struct kvm 
*kvm, u8 deliverable_mask)
                         if (test_and_set_bit(vcpu_id, gi->kicked_mask))
                                 return;
                         kvm_s390_vcpu_wakeup(vcpu);
+                       __gal_stats_inc(kvm, vcpus_kicked);
                         return;
                 }
         }
@@ -3013,11 +3015,14 @@ static enum hrtimer_restart 
gisa_vcpu_kicker(struct hrtimer *timer)

         pending_mask = gisa_get_ipm_or_restore_iam(gi);
         if (pending_mask) {
+               __gal_stats_inc(kvm, ipm_dirty);
                 __airqs_kick_single_vcpu(kvm, pending_mask);
                 hrtimer_forward_now(timer, ns_to_ktime(gi->expires));
+               __gal_stats_inc(kvm, timer_restart);
                 return HRTIMER_RESTART;
         };

+       __gal_stats_inc(kvm, timer_no_restart);
         return HRTIMER_NORESTART;
  }


Cheers,
Michael

Re: [PATCH v7 00/15] KVM: s390: make use of the GIB

[Christian Borntraeger]

Series Applied and queued.
see https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git/log/?h=next


On 31.01.2019 09:52, Michael Mueller wrote:
> The Guest Information Area (GIB) and its mechanics is part of
> the AIV facility. It provides hardware support to process
> Adapter Interruptions (AI) for pagable storage mode guests. 
> 
> Whenever a guest cannot process an AI because none of its
> vcpus is running in SIE context, a GIB alert interruption is
> sent to and handled by the host program to dispatch a vcpu of
> the respective guest.
> 
> Eventually, the AI is handled by the guest.
> 
> v6->v7:
>   patches 1/15 to 7/15
>      prepare the existing Interruption and GISA code for
>      the introduction of the GIB code. (kept from v6)
>   patches 8/15 to 10/15
>      kept from v6.
>   patch 11/15
>      kvm_s390_gisc_register() now uses a single conditional
>      branch to extend IAM restore value and to set the IAM
>      in GISA. 
>   patch 12/15
>      kvm_s390_clear_gisa() now refactored in its own patch.
>   patch 13/15
>      I'm keeping the 50 usec timer expiration as the statistic
>      data shows a single timer restart only.
>        gisa_get_ipm_or_restore_iam() now called when entering
>      kvm_s390_handle_wait(). That saves some of the timer
>      restarts.
>        Some modifications in kvm_s390_gisa_destroy()
>   patch 14/15
>      kept from v6.
>   patch 15/15
>      additional test on non NULL gisa origin in pending_irqs()
> 
> v5->v6:
>   Futher significant change was introduced with this version
>   now:
> 
>   a) During the alert list processing now a hrtimer is
>      started to kick an idle vcpu with open I/O interrupt
>      mask. It then is restarted to monitor the interruption
>      consumption and when the IPM is clean (no relevant
>      ISCs pending anymore) atomically restores the IAM
>      and don't restarts or if new ISCs arrive kick other
>      idle vcpus.
> 
>   patches 1/13 to 7/13:
>      prepare the existing Interruption and GISA code for
>      the introduction of the GIB code.
>   patches 8/13 to 10/13:
>      kept from v5.
>   patch 11/13:
>      Some comments added.
>   patch 12/13:
>      Significatly changed due to the hrtimer control.
>   patch 13/13:
>      Basically kept from v5 except for a slight reordering
>      that shortens the patch.
> 
> v4->v5:
>   Between these two versions some significant change was
>   introduced:
> 
>   a) During IPM look-up, the IAM gets atomically restored
>      if the IPM is clean. (The main strategy is: As soon no
>      airqs are pending anymore, get prepared for new ones
>      arriving).
> 
>   b) Kick a set of vcpus in WAIT state, that will be able
>      to handle all ISCs in IPM if possible. The main loop
>      that processes the GIB alert list is unchanged.
> 
>   patches 1/15 to 6/15:
>      prepare the existing Interruption and GISA code for
>      the introduction of the GIB code.
>   patches 7/15 to 9/15:
>      kept from v4. 
>   patch 10/15:
>      restores the IAM in get_ipm() when clean on request
>      with additional parameter irq_flags
>   patch 12/15:
>      modifies kvm_s390_deliver_pending_interrupts() such
>      that the IAM is not restored during the deliverable_irqs()
>      test as we are about to enter the SIE. Restoring the
>      IAM would trigger the alert mechanism unnecessarily
>      on SIE entry.
>   patch 13/15:
>      process_gib_alert_list() now triggers a minimal set
>      of idle vcpus capable the handle all pending ISCs.
>   patch 14/15:
>      the wiring is logical similar to v4 but uses different
>      routines
>   patch 15/15: 
>      kept from v4. 
> 
> v3->v4:
>   The central change of v4 is that the metric "vcpus_in_sie"
>   has been dropped. A least agressive IAM restore strategy
>   is being followed now. The consequence is that potentially
>   more GAL interruptions are to be handled by the host program.
>   The assuption as made that as soon the first vcpu is trying
>   to go into wait state, this could be the last vcpu being
>   open for I/O interruptions. Thus, to not loose the initiative
>   to deliver I/O interruptions as soon as possible, the IAM
>   is restored. Adding better heuristics can be done in future.
> 
>   I expect this to be the last version of the series.
>  
>   patch 01/12: Kernel msg now printed when FLIC fails
>                to register during arch inititialization.
>   patch 03/12: Commit message slightly changed with the
>   	       hint that gib initialization is called
> 	       by last patch of this serias.
>   patch 09/12: IAM now restored during kvm_s390_handle_wait()
>   patch 10/12: gib destroy case now handled upon unsuccessful
>   	       arch inititialization.
> 
> All other patches are unchanged.
> 
> v2->v3:
>   patch 01/12: Fixes a resource dealocation issue upon
>   	       unsuccessful exit from kvm_arch_init().
> 	       It is relevant for patch 11/12 as well. 
>   patch 08/12: The function process_gib_alert_list() has
>                been rewritten to reduce the number of GAL
> 	       interruptions on the host for many guest
> 	       scenarios.
>   patch 10/12: The IAM is now never cleared before SIE entry.
>                It will be cleared by millicode as soon the
> 	       first guest interruption is made pending and
> 	       not directly processed in SIE. The IAM gets
> 	       restored as soon a vm is idle, i.e. no vcpu
> 	       of that guest is in SIE context anymore.
>   patch 11/12: now integrates with new patch 01/12
>   patch 12/12: This patch is just experimental and shall not
>                be part of the final series.
> 
> The first patch of series v2: "leave AIs in IPM of GISA
> during vcpu_pre_run()" has been dropped.
> 
> All other patches are unchanged.
> 
> v1->v2:
>   patch 01/12: New patch. Tt can go also standalone without the
>   	       rest of the GIB series presented here but is a
> 	       requirement 
>   patch 03/12: kvm_s390_gib_init() now has a return code
>   patch 06/12: unlink_gib_alert_list() now uses cmpxchg() instead
>     	       of atomic_xchg()
>   patch 08/12: New patch. Foctors out __find_vcpu_for_floating_irq()
>   patch 09/12: process_gib_alert_list() has been simplified
>                the GISA clear/destroy cases have been removed
>   patch 11/12: kvm_s390_gisa_clear/destroy() now clear the IAM
>                and process the alert list directly
> 	       The IAM now gets restored in vcpu_post_run() only if
> 	       the GISA is not in alert list
>   patch 12/12: during kvm_arch_init() now the return code of
>     	       kvm_s390_gib_init() is honored.
> 
> All other patches are unchanged.
> 
> Michael Mueller (15):
>   KVM: s390: drop obsolete else path
>   KVM: s390: make bitmap declaration consistent
>   KVM: s390: move bitmap idle_mask into arch struct top level
>   KVM: s390: coding style kvm_s390_gisa_init/clear()
>   KVM: s390: use pending_irqs_no_gisa() where appropriate
>   KVM: s390: remove kvm_s390_ from gisa static inline functions
>   KVM: s390: introduce struct kvm_s390_gisa_interrupt
>   s390/cio: add function chsc_sgib()
>   KVM: s390: add the GIB and its related life-cyle functions
>   KVM: s390: add kvm reference to struct sie_page2
>   KVM: s390: add functions to (un)register GISC with GISA
>   KVM: s390: kvm_s390_gisa_clear() now clears the IPM only
>   KVM: s390: add gib_alert_irq_handler()
>   KVM: s390: start using the GIB
>   KVM: s390: fix possible null pointer dereference in pending_irqs()
> 
>  arch/s390/include/asm/cio.h      |   1 +
>  arch/s390/include/asm/irq.h      |   1 +
>  arch/s390/include/asm/isc.h      |   1 +
>  arch/s390/include/asm/kvm_host.h |  36 +++-
>  arch/s390/kernel/irq.c           |   1 +
>  arch/s390/kvm/interrupt.c        | 431 +++++++++++++++++++++++++++++++++++----
>  arch/s390/kvm/kvm-s390.c         |  13 +-
>  arch/s390/kvm/kvm-s390.h         |   4 +-
>  drivers/s390/cio/chsc.c          |  37 ++++
>  drivers/s390/cio/chsc.h          |   1 +
>  10 files changed, 480 insertions(+), 46 deletions(-)
>