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Subject[PATCH] xen: do not clear and mask evtchns in __xen_evtchn_do_upcall
xen: do not clear and mask evtchns in __xen_evtchn_do_upcall

Switch virqs and pirqs that don't need EOI (in Xen acktype ==
ACKTYPE_NONE, that means the machine irq is actually edge)
to handle_edge_irq.

Use handle_fasteoi_irq for pirqs that need eoi (they generally
correspond to level triggered irqs), no risk in loosing interrupts
because we have to EOI the irq anyway.

This change has the following benefits:

- it uses the very same handlers that Linux would use on native for the
same irqs;

- it uses these handlers in the same way Linux would use them: it let
Linux mask\unmask and ack the irq when Linux want to mask\unmask and ack
the irq;

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index 02b5a9c..4f15dde 100644
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -118,6 +118,8 @@ static DEFINE_PER_CPU(unsigned long [NR_EVENT_CHANNELS/BITS_PER_LONG],
static struct irq_chip xen_dynamic_chip;
static struct irq_chip xen_percpu_chip;
static struct irq_chip xen_pirq_chip;
+static void enable_dynirq(struct irq_data *data);
+static void disable_dynirq(struct irq_data *data);

/* Get info for IRQ */
static struct irq_info *info_for_irq(unsigned irq)
@@ -473,16 +475,6 @@ static void xen_free_irq(unsigned irq)
irq_free_desc(irq);
}

-static void pirq_unmask_notify(int irq)
-{
- struct physdev_eoi eoi = { .irq = pirq_from_irq(irq) };
-
- if (unlikely(pirq_needs_eoi(irq))) {
- int rc = HYPERVISOR_physdev_op(PHYSDEVOP_eoi, &eoi);
- WARN_ON(rc);
- }
-}
-
static void pirq_query_unmask(int irq)
{
struct physdev_irq_status_query irq_status;
@@ -506,6 +498,30 @@ static bool probing_irq(int irq)
return desc && desc->action == NULL;
}

+static void eoi_pirq(struct irq_data *data)
+{
+ int evtchn = evtchn_from_irq(data->irq);
+ struct irq_info *info = info_for_irq(data->irq);
+ struct physdev_eoi eoi = { .irq = info->u.pirq.gsi };
+ int rc = 0;
+
+ move_native_irq(data->irq);
+
+ if (VALID_EVTCHN(evtchn))
+ clear_evtchn(evtchn);
+
+ if (pirq_needs_eoi(data->irq)) {
+ rc = HYPERVISOR_physdev_op(PHYSDEVOP_eoi, &eoi);
+ WARN_ON(rc);
+ }
+}
+
+static void mask_ack_pirq(struct irq_data *data)
+{
+ disable_dynirq(data);
+ eoi_pirq(data);
+}
+
static unsigned int __startup_pirq(unsigned int irq)
{
struct evtchn_bind_pirq bind_pirq;
@@ -539,7 +555,7 @@ static unsigned int __startup_pirq(unsigned int irq)

out:
unmask_evtchn(evtchn);
- pirq_unmask_notify(irq);
+ eoi_pirq(irq_get_irq_data(irq));

return 0;
}
@@ -572,27 +588,6 @@ static void shutdown_pirq(struct irq_data *data)
info->evtchn = 0;
}

-static void enable_pirq(struct irq_data *data)
-{
- startup_pirq(data);
-}
-
-static void disable_pirq(struct irq_data *data)
-{
-}
-
-static void ack_pirq(struct irq_data *data)
-{
- int evtchn = evtchn_from_irq(data->irq);
-
- move_native_irq(data->irq);
-
- if (VALID_EVTCHN(evtchn)) {
- mask_evtchn(evtchn);
- clear_evtchn(evtchn);
- }
-}
-
static int find_irq_by_gsi(unsigned gsi)
{
struct irq_info *info;
@@ -639,9 +634,6 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
if (irq < 0)
goto out;

- set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
- handle_level_irq, name);
-
irq_op.irq = irq;
irq_op.vector = 0;

@@ -658,6 +650,14 @@ int xen_bind_pirq_gsi_to_irq(unsigned gsi,
xen_irq_info_pirq_init(irq, 0, pirq, gsi, irq_op.vector,
shareable ? PIRQ_SHAREABLE : 0);

+ pirq_query_unmask(irq);
+ if (pirq_needs_eoi(irq))
+ set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
+ handle_fasteoi_irq, name);
+ else
+ set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
+ handle_edge_irq, name);
+
out:
spin_unlock(&irq_mapping_update_lock);

@@ -691,7 +691,7 @@ int xen_bind_pirq_msi_to_irq(struct pci_dev *dev, struct msi_desc *msidesc,
goto out;

set_irq_chip_and_handler_name(irq, &xen_pirq_chip,
- handle_level_irq, name);
+ handle_edge_irq, name);

xen_irq_info_pirq_init(irq, 0, pirq, 0, vector, 0);
ret = irq_set_msi_desc(irq, msidesc);
@@ -773,7 +773,7 @@ int bind_evtchn_to_irq(unsigned int evtchn)
goto out;

set_irq_chip_and_handler_name(irq, &xen_dynamic_chip,
- handle_fasteoi_irq, "event");
+ handle_edge_irq, "event");

xen_irq_info_evtchn_init(irq, evtchn);
}
@@ -1181,9 +1181,6 @@ static void __xen_evtchn_do_upcall(void)
port = (word_idx * BITS_PER_LONG) + bit_idx;
irq = evtchn_to_irq[port];

- mask_evtchn(port);
- clear_evtchn(port);
-
if (irq != -1) {
desc = irq_to_desc(irq);
if (desc)
@@ -1339,12 +1336,18 @@ static void ack_dynirq(struct irq_data *data)
{
int evtchn = evtchn_from_irq(data->irq);

- move_masked_irq(data->irq);
+ move_native_irq(data->irq);

if (VALID_EVTCHN(evtchn))
- unmask_evtchn(evtchn);
+ clear_evtchn(evtchn);
}

+static void mask_ack_dynirq(struct irq_data *data)
+{
+ disable_dynirq(data);
+ ack_dynirq(data);
+}
+
static int retrigger_dynirq(struct irq_data *data)
{
int evtchn = evtchn_from_irq(data->irq);
@@ -1533,11 +1536,12 @@ void xen_irq_resume(void)
static struct irq_chip xen_dynamic_chip __read_mostly = {
.name = "xen-dyn",

- .irq_disable = disable_dynirq,
.irq_mask = disable_dynirq,
.irq_unmask = enable_dynirq,

- .irq_eoi = ack_dynirq,
+ .irq_ack = ack_dynirq,
+ .irq_mask_ack = mask_ack_dynirq,
+
.irq_set_affinity = set_affinity_irq,
.irq_retrigger = retrigger_dynirq,
};
@@ -1548,13 +1552,12 @@ static struct irq_chip xen_pirq_chip __read_mostly = {
.irq_startup = startup_pirq,
.irq_shutdown = shutdown_pirq,

- .irq_enable = enable_pirq,
- .irq_unmask = enable_pirq,
-
- .irq_disable = disable_pirq,
- .irq_mask = disable_pirq,
+ .irq_mask = disable_dynirq,
+ .irq_unmask = enable_dynirq,

- .irq_ack = ack_pirq,
+ .irq_ack = eoi_pirq,
+ .irq_eoi = eoi_pirq,
+ .irq_mask_ack = mask_ack_pirq,

.irq_set_affinity = set_affinity_irq,


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