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xen/events: don't unmask an event channel when an eoi is pending
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commit 25da461 upstream.

An event channel should be kept masked when an eoi is pending for it.
When being migrated to another cpu it might be unmasked, though.

In order to avoid this keep three different flags for each event channel
to be able to distinguish "normal" masking/unmasking from eoi related
masking/unmasking and temporary masking. The event channel should only
be able to generate an interrupt if all flags are cleared.

Cc: stable@vger.kernel.org
Fixes: 54c9de8 ("xen/events: add a new "late EOI" evtchn framework")
Reported-by: Julien Grall <julien@xen.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Tested-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Link: https://lore.kernel.org/r/20210306161833.4552-3-jgross@suse.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[boris -- corrected Fixed tag format]

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
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@jgross1 @gregkh
jgross1 authored and gregkh committed Mar 17, 2021
1 parent 37f4ed2 commit fad86da
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Showing 4 changed files with 80 additions and 41 deletions.
7 changes: 0 additions & 7 deletions drivers/xen/events/events_2l.c
View file
Expand Up @@ -77,12 +77,6 @@ static bool evtchn_2l_is_pending(evtchn_port_t port)
return sync_test_bit(port, BM(&s->evtchn_pending[0]));
}

static bool evtchn_2l_test_and_set_mask(evtchn_port_t port)
{
struct shared_info *s = HYPERVISOR_shared_info;
return sync_test_and_set_bit(port, BM(&s->evtchn_mask[0]));
}

static void evtchn_2l_mask(evtchn_port_t port)
{
struct shared_info *s = HYPERVISOR_shared_info;
Expand Down Expand Up @@ -376,7 +370,6 @@ static const struct evtchn_ops evtchn_ops_2l = {
.clear_pending = evtchn_2l_clear_pending,
.set_pending = evtchn_2l_set_pending,
.is_pending = evtchn_2l_is_pending,
.test_and_set_mask = evtchn_2l_test_and_set_mask,
.mask = evtchn_2l_mask,
.unmask = evtchn_2l_unmask,
.handle_events = evtchn_2l_handle_events,
Expand Down
101 changes: 80 additions & 21 deletions drivers/xen/events/events_base.c
View file
Expand Up @@ -97,13 +97,18 @@ struct irq_info {
short refcnt;
u8 spurious_cnt;
u8 is_accounted;
enum xen_irq_type type; /* type */
short type; /* type: IRQT_* */
u8 mask_reason; /* Why is event channel masked */
#define EVT_MASK_REASON_EXPLICIT 0x01
#define EVT_MASK_REASON_TEMPORARY 0x02
#define EVT_MASK_REASON_EOI_PENDING 0x04
unsigned irq;
evtchn_port_t evtchn; /* event channel */
unsigned short cpu; /* cpu bound */
unsigned short eoi_cpu; /* EOI must happen on this cpu-1 */
unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */
u64 eoi_time; /* Time in jiffies when to EOI. */
spinlock_t lock;

union {
unsigned short virq;
Expand Down Expand Up @@ -152,6 +157,7 @@ static DEFINE_RWLOCK(evtchn_rwlock);
* evtchn_rwlock
* IRQ-desc lock
* percpu eoi_list_lock
* irq_info->lock
*/

static LIST_HEAD(xen_irq_list_head);
Expand Down Expand Up @@ -302,6 +308,8 @@ static int xen_irq_info_common_setup(struct irq_info *info,
info->irq = irq;
info->evtchn = evtchn;
info->cpu = cpu;
info->mask_reason = EVT_MASK_REASON_EXPLICIT;
spin_lock_init(&info->lock);

ret = set_evtchn_to_irq(evtchn, irq);
if (ret < 0)
Expand Down Expand Up @@ -450,6 +458,34 @@ unsigned int cpu_from_evtchn(evtchn_port_t evtchn)
return ret;
}

static void do_mask(struct irq_info *info, u8 reason)
{
unsigned long flags;

spin_lock_irqsave(&info->lock, flags);

if (!info->mask_reason)
mask_evtchn(info->evtchn);

info->mask_reason |= reason;

spin_unlock_irqrestore(&info->lock, flags);
}

static void do_unmask(struct irq_info *info, u8 reason)
{
unsigned long flags;

spin_lock_irqsave(&info->lock, flags);

info->mask_reason &= ~reason;

if (!info->mask_reason)
unmask_evtchn(info->evtchn);

spin_unlock_irqrestore(&info->lock, flags);
}

#ifdef CONFIG_X86
static bool pirq_check_eoi_map(unsigned irq)
{
Expand Down Expand Up @@ -586,7 +622,7 @@ static void xen_irq_lateeoi_locked(struct irq_info *info, bool spurious)
}

info->eoi_time = 0;
unmask_evtchn(evtchn);
do_unmask(info, EVT_MASK_REASON_EOI_PENDING);
}

static void xen_irq_lateeoi_worker(struct work_struct *work)
Expand Down Expand Up @@ -831,7 +867,8 @@ static unsigned int __startup_pirq(unsigned int irq)
goto err;

out:
unmask_evtchn(evtchn);
do_unmask(info, EVT_MASK_REASON_EXPLICIT);

eoi_pirq(irq_get_irq_data(irq));

return 0;
Expand All @@ -858,7 +895,7 @@ static void shutdown_pirq(struct irq_data *data)
if (!VALID_EVTCHN(evtchn))
return;

mask_evtchn(evtchn);
do_mask(info, EVT_MASK_REASON_EXPLICIT);
xen_evtchn_close(evtchn);
xen_irq_info_cleanup(info);
}
Expand Down Expand Up @@ -1691,10 +1728,10 @@ void rebind_evtchn_irq(evtchn_port_t evtchn, int irq)
}

/* Rebind an evtchn so that it gets delivered to a specific cpu */
static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu)
static int xen_rebind_evtchn_to_cpu(struct irq_info *info, unsigned int tcpu)
{
struct evtchn_bind_vcpu bind_vcpu;
int masked;
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (!VALID_EVTCHN(evtchn))
return -1;
Expand All @@ -1710,7 +1747,7 @@ static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu)
* Mask the event while changing the VCPU binding to prevent
* it being delivered on an unexpected VCPU.
*/
masked = test_and_set_mask(evtchn);
do_mask(info, EVT_MASK_REASON_TEMPORARY);

/*
* If this fails, it usually just indicates that we're dealing with a
Expand All @@ -1720,8 +1757,7 @@ static int xen_rebind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int tcpu)
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_vcpu, &bind_vcpu) >= 0)
bind_evtchn_to_cpu(evtchn, tcpu, false);

if (!masked)
unmask_evtchn(evtchn);
do_unmask(info, EVT_MASK_REASON_TEMPORARY);

return 0;
}
Expand Down Expand Up @@ -1760,7 +1796,7 @@ static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,
unsigned int tcpu = select_target_cpu(dest);
int ret;

ret = xen_rebind_evtchn_to_cpu(evtchn_from_irq(data->irq), tcpu);
ret = xen_rebind_evtchn_to_cpu(info_for_irq(data->irq), tcpu);
if (!ret)
irq_data_update_effective_affinity(data, cpumask_of(tcpu));

Expand All @@ -1769,18 +1805,20 @@ static int set_affinity_irq(struct irq_data *data, const struct cpumask *dest,

static void enable_dynirq(struct irq_data *data)
{
evtchn_port_t evtchn = evtchn_from_irq(data->irq);
struct irq_info *info = info_for_irq(data->irq);
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (VALID_EVTCHN(evtchn))
unmask_evtchn(evtchn);
do_unmask(info, EVT_MASK_REASON_EXPLICIT);
}

static void disable_dynirq(struct irq_data *data)
{
evtchn_port_t evtchn = evtchn_from_irq(data->irq);
struct irq_info *info = info_for_irq(data->irq);
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (VALID_EVTCHN(evtchn))
mask_evtchn(evtchn);
do_mask(info, EVT_MASK_REASON_EXPLICIT);
}

static void ack_dynirq(struct irq_data *data)
Expand All @@ -1799,18 +1837,39 @@ static void mask_ack_dynirq(struct irq_data *data)
ack_dynirq(data);
}

static void lateeoi_ack_dynirq(struct irq_data *data)
{
struct irq_info *info = info_for_irq(data->irq);
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (VALID_EVTCHN(evtchn)) {
do_mask(info, EVT_MASK_REASON_EOI_PENDING);
clear_evtchn(evtchn);
}
}

static void lateeoi_mask_ack_dynirq(struct irq_data *data)
{
struct irq_info *info = info_for_irq(data->irq);
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (VALID_EVTCHN(evtchn)) {
do_mask(info, EVT_MASK_REASON_EXPLICIT);
clear_evtchn(evtchn);
}
}

static int retrigger_dynirq(struct irq_data *data)
{
evtchn_port_t evtchn = evtchn_from_irq(data->irq);
int masked;
struct irq_info *info = info_for_irq(data->irq);
evtchn_port_t evtchn = info ? info->evtchn : 0;

if (!VALID_EVTCHN(evtchn))
return 0;

masked = test_and_set_mask(evtchn);
do_mask(info, EVT_MASK_REASON_TEMPORARY);
set_evtchn(evtchn);
if (!masked)
unmask_evtchn(evtchn);
do_unmask(info, EVT_MASK_REASON_TEMPORARY);

return 1;
}
Expand Down Expand Up @@ -2024,8 +2083,8 @@ static struct irq_chip xen_lateeoi_chip __read_mostly = {
.irq_mask = disable_dynirq,
.irq_unmask = enable_dynirq,

.irq_ack = mask_ack_dynirq,
.irq_mask_ack = mask_ack_dynirq,
.irq_ack = lateeoi_ack_dynirq,
.irq_mask_ack = lateeoi_mask_ack_dynirq,

.irq_set_affinity = set_affinity_irq,
.irq_retrigger = retrigger_dynirq,
Expand Down
7 changes: 0 additions & 7 deletions drivers/xen/events/events_fifo.c
View file
Expand Up @@ -209,12 +209,6 @@ static bool evtchn_fifo_is_pending(evtchn_port_t port)
return sync_test_bit(EVTCHN_FIFO_BIT(PENDING, word), BM(word));
}

static bool evtchn_fifo_test_and_set_mask(evtchn_port_t port)
{
event_word_t *word = event_word_from_port(port);
return sync_test_and_set_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
}

static void evtchn_fifo_mask(evtchn_port_t port)
{
event_word_t *word = event_word_from_port(port);
Expand Down Expand Up @@ -423,7 +417,6 @@ static const struct evtchn_ops evtchn_ops_fifo = {
.clear_pending = evtchn_fifo_clear_pending,
.set_pending = evtchn_fifo_set_pending,
.is_pending = evtchn_fifo_is_pending,
.test_and_set_mask = evtchn_fifo_test_and_set_mask,
.mask = evtchn_fifo_mask,
.unmask = evtchn_fifo_unmask,
.handle_events = evtchn_fifo_handle_events,
Expand Down
6 changes: 0 additions & 6 deletions drivers/xen/events/events_internal.h
View file
Expand Up @@ -21,7 +21,6 @@ struct evtchn_ops {
void (*clear_pending)(evtchn_port_t port);
void (*set_pending)(evtchn_port_t port);
bool (*is_pending)(evtchn_port_t port);
bool (*test_and_set_mask)(evtchn_port_t port);
void (*mask)(evtchn_port_t port);
void (*unmask)(evtchn_port_t port);

Expand Down Expand Up @@ -84,11 +83,6 @@ static inline bool test_evtchn(evtchn_port_t port)
return evtchn_ops->is_pending(port);
}

static inline bool test_and_set_mask(evtchn_port_t port)
{
return evtchn_ops->test_and_set_mask(port);
}

static inline void mask_evtchn(evtchn_port_t port)
{
return evtchn_ops->mask(port);
Expand Down

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