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Code Issues Releases Activity

xen/intr: fix fallout from r278854

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r278854 introduced a race in the event channel handling code. We must make
sure that the pending bit is cleared before executing the filter, or else we
might miss other events that would be injected after the filter has ran but
before the pending bit is cleared.

While there also mask event channels while FreeBSD executes the ithread
bound to that event channel. This refrains Xen from injecting more
interrupts while the ithread has not finished it's work.

Sponsored by: Citrix Systems R&D
Reported by: sbruno, robak
Tested by: robak
This commit is contained in:
Roger Pau Monné 2015-02-26 16:05:09 +00:00
parent 771d671beb
commit 544b31a3e3
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=279325
1 changed files with 23 additions and 14 deletions
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37
sys/x86/xen/xen_intr.c
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@ -128,6 +128,7 @@ struct xenisrc {
u_int xi_close:1; /* close on unbind? */
u_int xi_activehi:1;
u_int xi_edgetrigger:1;
u_int xi_masked:1;
};
#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
@ -578,12 +579,11 @@ xen_intr_handle_upcall(struct trapframe *trap_frame)
/* process port */
port = (l1i * LONG_BIT) + l2i;
synch_clear_bit(port, &s->evtchn_pending[0]);
isrc = xen_intr_port_to_isrc[port];
if (__predict_false(isrc == NULL)) {
synch_clear_bit(port, &s->evtchn_pending[0]);
if (__predict_false(isrc == NULL))
continue;
}
/* Make sure we are firing on the right vCPU */
KASSERT((isrc->xi_cpu == PCPU_GET(cpuid)),
@ -930,11 +930,21 @@ xen_intr_assign_cpu(struct intsrc *base_isrc, u_int apic_id)
* acknowledgements.
*/
static void
xen_intr_disable_source(struct intsrc *isrc, int eoi)
xen_intr_disable_source(struct intsrc *base_isrc, int eoi)
{
struct xenisrc *isrc;
if (eoi == PIC_EOI)
xen_intr_eoi_source(isrc);
isrc = (struct xenisrc *)base_isrc;
/*
* NB: checking if the event channel is already masked is
* needed because the event channel user-space device
* masks event channels on it's filter as part of it's
* normal operation, and those shouldn't be automatically
* unmasked by the generic interrupt code. The event channel
* device will unmask them when needed.
*/
isrc->xi_masked = !!evtchn_test_and_set_mask(isrc->xi_port);
}
/*
@ -943,8 +953,14 @@ xen_intr_disable_source(struct intsrc *isrc, int eoi)
* \param isrc The interrupt source to unmask (if necessary).
*/
static void
xen_intr_enable_source(struct intsrc *isrc)
xen_intr_enable_source(struct intsrc *base_isrc)
{
struct xenisrc *isrc;
isrc = (struct xenisrc *)base_isrc;
if (isrc->xi_masked == 0)
evtchn_unmask_port(isrc->xi_port);
}
/*
@ -955,11 +971,6 @@ xen_intr_enable_source(struct intsrc *isrc)
static void
xen_intr_eoi_source(struct intsrc *base_isrc)
{
struct xenisrc *isrc;
isrc = (struct xenisrc *)base_isrc;
synch_clear_bit(isrc->xi_port,
&HYPERVISOR_shared_info->evtchn_pending[0]);
}
/*
@ -1025,8 +1036,6 @@ xen_intr_pirq_eoi_source(struct intsrc *base_isrc)
isrc = (struct xenisrc *)base_isrc;
synch_clear_bit(isrc->xi_port,
&HYPERVISOR_shared_info->evtchn_pending[0]);
if (test_bit(isrc->xi_pirq, xen_intr_pirq_eoi_map)) {
struct physdev_eoi eoi = { .irq = isrc->xi_pirq };