linux/drivers/xen/events/events_internal.h
Juergen Gross 5f7f77400a xen/events: block rogue events for some time
In order to avoid high dom0 load due to rogue guests sending events at
high frequency, block those events in case there was no action needed
in dom0 to handle the events.

This is done by adding a per-event counter, which set to zero in case
an EOI without the XEN_EOI_FLAG_SPURIOUS is received from a backend
driver, and incremented when this flag has been set. In case the
counter is 2 or higher delay the EOI by 1 << (cnt - 2) jiffies, but
not more than 1 second.

In order not to waste memory shorten the per-event refcnt to two bytes
(it should normally never exceed a value of 2). Add an overflow check
to evtchn_get() to make sure the 2 bytes really won't overflow.

This is part of XSA-332.

Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Wei Liu <wl@xen.org>
2020-10-20 10:22:19 +02:00

162 lines
3.7 KiB
C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* Xen Event Channels (internal header)
*
* Copyright (C) 2013 Citrix Systems R&D Ltd.
*/
#ifndef __EVENTS_INTERNAL_H__
#define __EVENTS_INTERNAL_H__
/* Interrupt types. */
enum xen_irq_type {
IRQT_UNBOUND = 0,
IRQT_PIRQ,
IRQT_VIRQ,
IRQT_IPI,
IRQT_EVTCHN
};
/*
* Packed IRQ information:
* type - enum xen_irq_type
* event channel - irq->event channel mapping
* cpu - cpu this event channel is bound to
* index - type-specific information:
* PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM
* guest, or GSI (real passthrough IRQ) of the device.
* VIRQ - virq number
* IPI - IPI vector
* EVTCHN -
*/
struct irq_info {
struct list_head list;
struct list_head eoi_list;
short refcnt;
short spurious_cnt;
enum xen_irq_type type; /* type */
unsigned irq;
evtchn_port_t evtchn; /* event channel */
unsigned short cpu; /* cpu bound */
unsigned short eoi_cpu; /* EOI must happen on this cpu */
unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */
u64 eoi_time; /* Time in jiffies when to EOI. */
union {
unsigned short virq;
enum ipi_vector ipi;
struct {
unsigned short pirq;
unsigned short gsi;
unsigned char vector;
unsigned char flags;
uint16_t domid;
} pirq;
} u;
};
#define PIRQ_NEEDS_EOI (1 << 0)
#define PIRQ_SHAREABLE (1 << 1)
#define PIRQ_MSI_GROUP (1 << 2)
struct evtchn_loop_ctrl;
struct evtchn_ops {
unsigned (*max_channels)(void);
unsigned (*nr_channels)(void);
int (*setup)(struct irq_info *info);
void (*bind_to_cpu)(struct irq_info *info, unsigned cpu);
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);
void (*handle_events)(unsigned cpu, struct evtchn_loop_ctrl *ctrl);
void (*resume)(void);
int (*percpu_init)(unsigned int cpu);
int (*percpu_deinit)(unsigned int cpu);
};
extern const struct evtchn_ops *evtchn_ops;
extern int **evtchn_to_irq;
int get_evtchn_to_irq(evtchn_port_t evtchn);
void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl);
struct irq_info *info_for_irq(unsigned irq);
unsigned cpu_from_irq(unsigned irq);
unsigned int cpu_from_evtchn(evtchn_port_t evtchn);
static inline unsigned xen_evtchn_max_channels(void)
{
return evtchn_ops->max_channels();
}
/*
* Do any ABI specific setup for a bound event channel before it can
* be unmasked and used.
*/
static inline int xen_evtchn_port_setup(struct irq_info *info)
{
if (evtchn_ops->setup)
return evtchn_ops->setup(info);
return 0;
}
static inline void xen_evtchn_port_bind_to_cpu(struct irq_info *info,
unsigned cpu)
{
evtchn_ops->bind_to_cpu(info, cpu);
}
static inline void clear_evtchn(evtchn_port_t port)
{
evtchn_ops->clear_pending(port);
}
static inline void set_evtchn(evtchn_port_t port)
{
evtchn_ops->set_pending(port);
}
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);
}
static inline void unmask_evtchn(evtchn_port_t port)
{
return evtchn_ops->unmask(port);
}
static inline void xen_evtchn_handle_events(unsigned cpu,
struct evtchn_loop_ctrl *ctrl)
{
return evtchn_ops->handle_events(cpu, ctrl);
}
static inline void xen_evtchn_resume(void)
{
if (evtchn_ops->resume)
evtchn_ops->resume();
}
void xen_evtchn_2l_init(void);
int xen_evtchn_fifo_init(void);
#endif /* #ifndef __EVENTS_INTERNAL_H__ */