Re: [PATCH v5 14/15] KVM: s390: add and wire function gib_alert_irq_handler()

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On 03.01.19 16:16, Pierre Morel wrote:
On 19/12/2018 20:17, 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@xxxxxxxxxxxxx>
---
  arch/s390/include/asm/irq.h |  1 +
  arch/s390/include/asm/isc.h |  1 +
  arch/s390/kernel/irq.c      |  1 +
  arch/s390/kvm/interrupt.c   | 36 ++++++++++++++++++++++++++++++++++--
  4 files changed, 37 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/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 03e7ba4f215a..79b9c262479b 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"
@@ -3043,7 +3044,7 @@ static void __floating_airqs_kick(struct kvm *kvm)
  #define NONE_GISA_ADDR 0x00000001UL
  #define GISA_ADDR_MASK 0xfffff000UL
-static void __maybe_unused process_gib_alert_list(void)
+static void process_gib_alert_list(void)
  {
      u32 final, next_alert, origin = 0UL;
      struct kvm_s390_gisa *gisa;
@@ -3091,7 +3092,10 @@ void kvm_s390_gisa_clear(struct kvm *kvm)
  {
      if (!kvm->arch.gisa)
          return;
+    if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
+        process_gib_alert_list();

We call process_gib_alert_list() from different contexts shouldn't we protect the calls?

That should not be necessary as the xcgh() guarantees that both
instances will work on gib alert lists with disjunctive gisas.



      nullify_gisa(kvm->arch.gisa);
+    set_iam(kvm->arch.gisa, kvm->arch.iam);
      VM_EVENT(kvm, 3, "gisa 0x%pK cleared", kvm->arch.gisa);
  }
@@ -3111,6 +3115,8 @@ void kvm_s390_gisa_destroy(struct kvm *kvm)
  {
      if (!kvm->arch.gisa)
          return;
+    if (set_iam(kvm->arch.gisa, 0) == -EBUSY)
+        process_gib_alert_list();

idem.

      kvm->arch.gisa = NULL;
  }
@@ -3159,11 +3165,23 @@ 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();

idem.

+}
+
+static struct airq_struct gib_alert_irq = {
+    .handler = gib_alert_irq_handler,
+    .lsi_ptr = &gib_alert_irq.lsi_mask,
+};
+






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