Remove MSI IRQ storms prevention logic

The reason is:
1. The logic has negative impact on 10G NIC performance (assigned to
guest) by lowering the interrupt frequency that Xen can handle.
2. Xen already has IRQ rate limit logic, which can also help to
prevent IRQ storms.

Signed-off-by: Shan Haitao <haitao.shan@intel.com>

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 8b05f1adc394a7bfe97d9abe847c64b3aa6fda52..fabe0e91e8464436bcdb8ea314f1ebeedd6bc490 100644 (file)
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -400,8 +400,6 @@ void vlapic_EOI_set(struct vlapic *vlapic)
 
     if ( vlapic_test_and_clear_vector(vector, &vlapic->regs->data[APIC_TMR]) )
         vioapic_update_EOI(vlapic_domain(vlapic), vector);
-
-    hvm_dpci_msi_eoi(current->domain, vector);
 }
 
 int vlapic_ipi(

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 98f808450ca755c74fb0bbfdda1d3371d6ac3df9..c89a3c43c272fde080fcacb05333770f4b0c2296 100644 (file)
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -790,22 +790,6 @@ static inline void clear_pirq_eoi(struct domain *d, unsigned int irq)
         clear_bit(irq, d->arch.pv_domain.pirq_eoi_map);
 }
 
-static void _irq_guest_eoi(struct irq_desc *desc)
-{
-    irq_guest_action_t *action = (irq_guest_action_t *)desc->action;
-    unsigned int i, irq = desc - irq_desc;
-
-    if ( !(desc->status & IRQ_GUEST_EOI_PENDING) )
-        return;
-
-    for ( i = 0; i < action->nr_guests; ++i )
-        clear_pirq_eoi(action->guest[i],
-                       domain_irq_to_pirq(action->guest[i], irq));
-
-    desc->status &= ~(IRQ_INPROGRESS|IRQ_GUEST_EOI_PENDING);
-    desc->handler->enable(irq);
-}
-
 static void set_eoi_ready(void *data);
 
 static void irq_guest_eoi_timer_fn(void *data)
@@ -849,9 +833,6 @@ static void irq_guest_eoi_timer_fn(void *data)
         on_selected_cpus(&cpu_eoi_map, set_eoi_ready, desc, 0);
         spin_lock_irq(&desc->lock);
         break;
-    case ACKTYPE_NONE:
-        _irq_guest_eoi(desc);
-        break;
     }
 
  out:
@@ -863,7 +844,7 @@ static void __do_IRQ_guest(int irq)
     struct irq_desc         *desc = irq_to_desc(irq);
     irq_guest_action_t *action = (irq_guest_action_t *)desc->action;
     struct domain      *d;
-    int                 i, sp, already_pending = 0;
+    int                 i, sp;
     struct pending_eoi *peoi = this_cpu(pending_eoi);
     int vector = get_irq_regs()->entry_vector;
 
@@ -897,45 +878,16 @@ static void __do_IRQ_guest(int irq)
         if ( (action->ack_type != ACKTYPE_NONE) &&
              !test_and_set_bool(pirq->masked) )
             action->in_flight++;
-        if ( hvm_do_IRQ_dpci(d, pirq) )
-        {
-            if ( action->ack_type == ACKTYPE_NONE )
-            {
-                already_pending += !!(desc->status & IRQ_INPROGRESS);
-                desc->status |= IRQ_INPROGRESS; /* cleared during hvm eoi */
-            }
-        }
-        else if ( send_guest_pirq(d, pirq) &&
-                  (action->ack_type == ACKTYPE_NONE) )
-        {
-            already_pending++;
-        }
+        if ( !hvm_do_IRQ_dpci(d, pirq) )
+            send_guest_pirq(d, pirq);
     }
 
-    stop_timer(&action->eoi_timer);
-
-    if ( (action->ack_type == ACKTYPE_NONE) &&
-         (already_pending == action->nr_guests) )
+    if ( action->ack_type != ACKTYPE_NONE )
     {
-        desc->handler->disable(irq);
-        desc->status |= IRQ_GUEST_EOI_PENDING;
-        for ( i = 0; i < already_pending; ++i )
-        {
-            d = action->guest[i];
-            set_pirq_eoi(d, domain_irq_to_pirq(d, irq));
-            /*
-             * Could check here whether the guest unmasked the event by now
-             * (or perhaps just re-issue the send_guest_pirq()), and if it
-             * can now accept the event,
-             * - clear all the pirq_eoi bits we already set,
-             * - re-enable the vector, and
-             * - skip the timer setup below.
-             */
-        }
+        stop_timer(&action->eoi_timer);
+        migrate_timer(&action->eoi_timer, smp_processor_id());
+        set_timer(&action->eoi_timer, NOW() + MILLISECS(1));
     }
-
-    migrate_timer(&action->eoi_timer, smp_processor_id());
-    set_timer(&action->eoi_timer, NOW() + MILLISECS(1));
 }
 
 /*
@@ -1183,13 +1135,6 @@ void desc_guest_eoi(struct irq_desc *desc, struct pirq *pirq)
     action = (irq_guest_action_t *)desc->action;
     irq = desc - irq_desc;
 
-    if ( action->ack_type == ACKTYPE_NONE )
-    {
-        ASSERT(!pirq->masked);
-        stop_timer(&action->eoi_timer);
-        _irq_guest_eoi(desc);
-    }
-
     if ( unlikely(!test_and_clear_bool(pirq->masked)) ||
          unlikely(--action->in_flight != 0) )
     {
@@ -1468,10 +1413,6 @@ static irq_guest_action_t *__pirq_guest_unbind(
             spin_lock_irq(&desc->lock);
         }
         break;
-    case ACKTYPE_NONE:
-        stop_timer(&action->eoi_timer);
-        _irq_guest_eoi(desc);
-        break;
     }
 
     /*
@@ -1509,7 +1450,7 @@ static irq_guest_action_t *__pirq_guest_unbind(
     BUG_ON(!cpus_empty(action->cpu_eoi_map));
 
     desc->action = NULL;
-    desc->status &= ~(IRQ_GUEST|IRQ_GUEST_EOI_PENDING|IRQ_INPROGRESS);
+    desc->status &= ~(IRQ_GUEST|IRQ_INPROGRESS);
     desc->handler->shutdown(irq);
 
     /* Caller frees the old guest descriptor block. */

diff --git a/xen/drivers/passthrough/io.c b/xen/drivers/passthrough/io.c
index 788c8f6e50bfa91c4eaf7595e4ee71d3304ceba0..bce86adafc757df342096bab86737d7c0af5c8cf 100644 (file)
--- a/xen/drivers/passthrough/io.c
+++ b/xen/drivers/passthrough/io.c
@@ -421,58 +421,6 @@ int hvm_do_IRQ_dpci(struct domain *d, struct pirq *pirq)
 }
 
 #ifdef SUPPORT_MSI_REMAPPING
-/* called with d->event_lock held */
-static void __msi_pirq_eoi(struct hvm_pirq_dpci *pirq_dpci)
-{
-    irq_desc_t *desc;
-
-    if ( (pirq_dpci->flags & HVM_IRQ_DPCI_MAPPED) &&
-         (pirq_dpci->flags & HVM_IRQ_DPCI_MACH_MSI) )
-    {
-        struct pirq *pirq = dpci_pirq(pirq_dpci);
-
-         BUG_ON(!local_irq_is_enabled());
-         desc = pirq_spin_lock_irq_desc(pirq, NULL);
-         if ( !desc )
-            return;
-
-         desc->status &= ~IRQ_INPROGRESS;
-         desc_guest_eoi(desc, pirq);
-    }
-}
-
-static int _hvm_dpci_msi_eoi(struct domain *d,
-                             struct hvm_pirq_dpci *pirq_dpci, void *arg)
-{
-    int vector = (long)arg;
-
-    if ( (pirq_dpci->flags & HVM_IRQ_DPCI_MACH_MSI) &&
-         (pirq_dpci->gmsi.gvec == vector) )
-    {
-        int dest = pirq_dpci->gmsi.gflags & VMSI_DEST_ID_MASK;
-        int dest_mode = !!(pirq_dpci->gmsi.gflags & VMSI_DM_MASK);
-
-        if ( vlapic_match_dest(vcpu_vlapic(current), NULL, 0, dest,
-                               dest_mode) )
-        {
-            __msi_pirq_eoi(pirq_dpci);
-            return 1;
-        }
-    }
-
-    return 0;
-}
-
-void hvm_dpci_msi_eoi(struct domain *d, int vector)
-{
-    if ( !iommu_enabled || !d->arch.hvm_domain.irq.dpci )
-       return;
-
-    spin_lock(&d->event_lock);
-    pt_pirq_iterate(d, _hvm_dpci_msi_eoi, (void *)(long)vector);
-    spin_unlock(&d->event_lock);
-}
-
 static int hvm_pci_msi_assert(struct domain *d,
                               struct hvm_pirq_dpci *pirq_dpci)
 {
@@ -510,14 +458,6 @@ static int _hvm_dirq_assist(struct domain *d, struct hvm_pirq_dpci *pirq_dpci,
             else
                 hvm_pci_intx_assert(d, device, intx);
             pirq_dpci->pending++;
-
-#ifdef SUPPORT_MSI_REMAPPING
-            if ( pirq_dpci->flags & HVM_IRQ_DPCI_TRANSLATE )
-            {
-                /* for translated MSI to INTx interrupt, eoi as early as possible */
-                __msi_pirq_eoi(pirq_dpci);
-            }
-#endif
         }
 
         /*

diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index ce2bcb373fb6e7787dd0f1cef75c15291f6e48df..419f25f41f62f5e8c225f38a3987b708dd3625d2 100644 (file)
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -139,6 +139,5 @@ struct hvm_hw_stdvga {
 void stdvga_init(struct domain *d);
 void stdvga_deinit(struct domain *d);
 
-extern void hvm_dpci_msi_eoi(struct domain *d, int vector);
 #endif /* __ASM_X86_HVM_IO_H__ */
 

diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index 573ace7e298a9dba84886ef37e8b2d2cffa90af7..32251c5b56f778dabc2aa4ba327490c756709394 100644 (file)
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -25,7 +25,6 @@ struct irqaction {
 #define IRQ_PENDING    4       /* IRQ pending - replay on enable */
 #define IRQ_REPLAY     8       /* IRQ has been replayed but not acked yet */
 #define IRQ_GUEST       16      /* IRQ is handled by guest OS(es) */
-#define IRQ_GUEST_EOI_PENDING 32 /* IRQ was disabled, pending a guest EOI */
 #define IRQ_MOVE_PENDING      64  /* IRQ is migrating to another CPUs */
 #define IRQ_PER_CPU     256     /* IRQ is per CPU */