When migrating IO-APIC line level interrupts between PCPUs, the
migration code rewrites the IO-APIC entry to point to the new
CPU/Vector before EOI'ing it.
The EOI process says that EOI'ing the Local APIC will cause a
broadcast with the vector number, which the IO-APIC must listen to to
clear the IRR and Status bits.
In the case of migrating, the IO-APIC has already been
reprogrammed so the EOI broadcast with the old vector fails to match
the new vector, leaving the IO-APIC with an outstanding vector,
preventing any more use of that line interrupt. This causes a lockup
especially when your root device is using PCI INTA (megaraid_sas
driver *ehem*)
However, the problem is mostly hidden because send_cleanup_vector()
causes a cleanup of all moving vectors on the current PCPU in such a
way which does not cause the problem, and if the problem has occured,
the writes it makes to the IO-APIC clears the IRR and Status bits
which unlocks the problem.
This fix is distinctly a temporary hack, waiting on a cleanup of the
irq code. It checks for the edge case where we have moved the irq,
and manually EOI's the old vector with the IO-APIC which correctly
clears the IRR and Status bits. Also, it protects the code which
updates irq_cfg by disabling interrupts.
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
diff -r 227130622561 -r a95fd5d03c20 xen/arch/x86/hpet.c
--- a/xen/arch/x86/hpet.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/arch/x86/hpet.c Tue Aug 30 15:15:56 2011 +0100
@@ -301,7 +301,7 @@ static void hpet_msi_ack(unsigned int ir
ack_APIC_irq();
}
-static void hpet_msi_end(unsigned int irq)
+static void hpet_msi_end(unsigned int irq, u8 vector)
{
}
diff -r 227130622561 -r a95fd5d03c20 xen/arch/x86/i8259.c
--- a/xen/arch/x86/i8259.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/arch/x86/i8259.c Tue Aug 30 15:15:56 2011 +0100
@@ -93,7 +93,7 @@ static unsigned int startup_8259A_irq(un
return 0; /* never anything pending */
}
-static void end_8259A_irq(unsigned int irq)
+static void end_8259A_irq(unsigned int irq, u8 vector)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
enable_8259A_irq(irq);
diff -r 227130622561 -r a95fd5d03c20 xen/arch/x86/io_apic.c
--- a/xen/arch/x86/io_apic.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/arch/x86/io_apic.c Tue Aug 30 15:15:56 2011 +0100
@@ -1690,7 +1690,7 @@ static void mask_and_ack_level_ioapic_ir
}
}
-static void end_level_ioapic_irq (unsigned int irq)
+static void end_level_ioapic_irq (unsigned int irq, u8 vector)
{
unsigned long v;
int i;
@@ -1739,6 +1739,14 @@ static void end_level_ioapic_irq (unsign
*/
i = IO_APIC_VECTOR(irq);
+ /* Manually EOI the old vector if we are moving to the new */
+ if ( vector && i != vector )
+ {
+ int ioapic;
+ for (ioapic = 0; ioapic < nr_ioapics; ioapic++)
+ io_apic_eoi(ioapic, i);
+ }
+
v = apic_read(APIC_TMR + ((i & ~0x1f) >> 1));
ack_APIC_irq();
@@ -1762,7 +1770,10 @@ static void disable_edge_ioapic_irq(unsi
{
}
-#define end_edge_ioapic_irq disable_edge_ioapic_irq
+static void end_edge_ioapic_irq(unsigned int irq, u8 vector)
+{
+}
+
/*
* Level and edge triggered IO-APIC interrupts need different handling,
@@ -1811,7 +1822,7 @@ static void ack_msi_irq(unsigned int irq
ack_APIC_irq(); /* ACKTYPE_NONE */
}
-static void end_msi_irq(unsigned int irq)
+static void end_msi_irq(unsigned int irq, u8 vector)
{
if ( !msi_maskable_irq(irq_desc[irq].msi_desc) )
ack_APIC_irq(); /* ACKTYPE_EOI */
diff -r 227130622561 -r a95fd5d03c20 xen/arch/x86/irq.c
--- a/xen/arch/x86/irq.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/arch/x86/irq.c Tue Aug 30 15:15:56 2011 +0100
@@ -345,6 +345,7 @@ static void __do_IRQ_guest(int vector);
void no_action(int cpl, void *dev_id, struct cpu_user_regs *regs) { }
static void enable_none(unsigned int vector) { }
+static void end_none(unsigned int irq, u8 vector) { }
static unsigned int startup_none(unsigned int vector) { return 0; }
static void disable_none(unsigned int vector) { }
static void ack_none(unsigned int irq)
@@ -353,7 +354,6 @@ static void ack_none(unsigned int irq)
}
#define shutdown_none disable_none
-#define end_none enable_none
hw_irq_controller no_irq_type = {
"none",
@@ -381,6 +381,7 @@ int __assign_irq_vector(int irq, struct
static int current_vector = FIRST_DYNAMIC_VECTOR, current_offset = 0;
unsigned int old_vector;
int cpu, err;
+ unsigned long flags;
cpumask_t tmp_mask;
old_vector = irq_to_vector(irq);
@@ -431,6 +432,7 @@ next:
/* Found one! */
current_vector = vector;
current_offset = offset;
+ local_irq_save(flags);
if (old_vector) {
cfg->move_in_progress = 1;
cpus_copy(cfg->old_cpu_mask, cfg->cpu_mask);
@@ -450,6 +452,7 @@ next:
if (IO_APIC_IRQ(irq))
irq_vector[irq] = vector;
err = 0;
+ local_irq_restore(flags);
break;
}
return err;
@@ -657,7 +660,7 @@ asmlinkage void do_IRQ(struct cpu_user_r
desc->status &= ~IRQ_INPROGRESS;
out:
- desc->handler->end(irq);
+ desc->handler->end(irq, regs->entry_vector);
out_no_end:
spin_unlock(&desc->lock);
irq_exit();
@@ -857,7 +860,7 @@ static void irq_guest_eoi_timer_fn(void
switch ( action->ack_type )
{
case ACKTYPE_UNMASK:
- desc->handler->end(irq);
+ desc->handler->end(irq, 0);
break;
case ACKTYPE_EOI:
cpu_eoi_map = action->cpu_eoi_map;
@@ -885,7 +888,7 @@ static void __do_IRQ_guest(int irq)
/* An interrupt may slip through while freeing an ACKTYPE_EOI irq. */
ASSERT(action->ack_type == ACKTYPE_EOI);
ASSERT(desc->status & IRQ_DISABLED);
- desc->handler->end(irq);
+ desc->handler->end(irq, vector);
return;
}
@@ -1099,7 +1102,7 @@ static void flush_ready_eoi(void)
ASSERT(irq > 0);
desc = irq_to_desc(irq);
spin_lock(&desc->lock);
- desc->handler->end(irq);
+ desc->handler->end(irq, peoi[sp].vector);
spin_unlock(&desc->lock);
}
@@ -1177,7 +1180,7 @@ void desc_guest_eoi(struct irq_desc *des
if ( action->ack_type == ACKTYPE_UNMASK )
{
ASSERT(cpus_empty(action->cpu_eoi_map));
- desc->handler->end(irq);
+ desc->handler->end(irq, 0);
spin_unlock_irq(&desc->lock);
return;
}
@@ -1431,7 +1434,7 @@ static irq_guest_action_t *__pirq_guest_
case ACKTYPE_UNMASK:
if ( test_and_clear_bool(pirq->masked) &&
(--action->in_flight == 0) )
- desc->handler->end(irq);
+ desc->handler->end(irq, 0);
break;
case ACKTYPE_EOI:
/* NB. If #guests == 0 then we clear the eoi_map later on. */
diff -r 227130622561 -r a95fd5d03c20 xen/drivers/passthrough/amd/iommu_init.c
--- a/xen/drivers/passthrough/amd/iommu_init.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/drivers/passthrough/amd/iommu_init.c Tue Aug 30 15:15:56 2011 +0100
@@ -441,7 +441,7 @@ static unsigned int iommu_msi_startup(un
return 0;
}
-static void iommu_msi_end(unsigned int irq)
+static void iommu_msi_end(unsigned int irq, u8 vector)
{
iommu_msi_unmask(irq);
ack_APIC_irq();
diff -r 227130622561 -r a95fd5d03c20 xen/drivers/passthrough/vtd/iommu.c
--- a/xen/drivers/passthrough/vtd/iommu.c Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c Tue Aug 30 15:15:56 2011 +0100
@@ -971,7 +971,7 @@ static unsigned int dma_msi_startup(unsi
return 0;
}
-static void dma_msi_end(unsigned int irq)
+static void dma_msi_end(unsigned int irq, u8 vector)
{
dma_msi_unmask(irq);
ack_APIC_irq();
diff -r 227130622561 -r a95fd5d03c20 xen/include/xen/irq.h
--- a/xen/include/xen/irq.h Thu Aug 25 12:03:14 2011 +0100
+++ b/xen/include/xen/irq.h Tue Aug 30 15:15:56 2011 +0100
@@ -44,7 +44,7 @@ struct hw_interrupt_type {
void (*enable)(unsigned int irq);
void (*disable)(unsigned int irq);
void (*ack)(unsigned int irq);
- void (*end)(unsigned int irq);
+ void (*end)(unsigned int irq, u8 vector);
void (*set_affinity)(unsigned int irq, cpumask_t mask);
};
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