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vfio: Introduce interface to flush virqfd inject workqueue

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In order to synchronize changes that can affect the thread callback,
introduce an interface to force a flush of the inject workqueue.  The
irqfd pointer is only valid under spinlock, but the workqueue cannot
be flushed under spinlock.  Therefore the flush work for the irqfd is
queued under spinlock.  The vfio_irqfd_cleanup_wq workqueue is re-used
for queuing this work such that flushing the workqueue is also ordered
relative to shutdown.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-4-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2024-03-08 16:05:24 -07:00
parent 810cd4bb53
commit b620ecbd17
2 changed files with 23 additions and 0 deletions
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21
drivers/vfio/virqfd.c
View File

@ -101,6 +101,13 @@ static void virqfd_inject(struct work_struct *work)
virqfd->thread(virqfd->opaque, virqfd->data);
}
static void virqfd_flush_inject(struct work_struct *work)
{
struct virqfd *virqfd = container_of(work, struct virqfd, flush_inject);
flush_work(&virqfd->inject);
}
int vfio_virqfd_enable(void *opaque,
int (*handler)(void *, void *),
void (*thread)(void *, void *),
@ -124,6 +131,7 @@ int vfio_virqfd_enable(void *opaque,
INIT_WORK(&virqfd->shutdown, virqfd_shutdown);
INIT_WORK(&virqfd->inject, virqfd_inject);
INIT_WORK(&virqfd->flush_inject, virqfd_flush_inject);
irqfd = fdget(fd);
if (!irqfd.file) {
@ -213,3 +221,16 @@ void vfio_virqfd_disable(struct virqfd **pvirqfd)
flush_workqueue(vfio_irqfd_cleanup_wq);
}
EXPORT_SYMBOL_GPL(vfio_virqfd_disable);
void vfio_virqfd_flush_thread(struct virqfd **pvirqfd)
{
unsigned long flags;
spin_lock_irqsave(&virqfd_lock, flags);
if (*pvirqfd && (*pvirqfd)->thread)
queue_work(vfio_irqfd_cleanup_wq, &(*pvirqfd)->flush_inject);
spin_unlock_irqrestore(&virqfd_lock, flags);
flush_workqueue(vfio_irqfd_cleanup_wq);
}
EXPORT_SYMBOL_GPL(vfio_virqfd_flush_thread);

2
include/linux/vfio.h
View File

@ -356,6 +356,7 @@ struct virqfd {
wait_queue_entry_t wait;
poll_table pt;
struct work_struct shutdown;
struct work_struct flush_inject;
struct virqfd **pvirqfd;
};
@ -363,5 +364,6 @@ int vfio_virqfd_enable(void *opaque, int (*handler)(void *, void *),
void (*thread)(void *, void *), void *data,
struct virqfd **pvirqfd, int fd);
void vfio_virqfd_disable(struct virqfd **pvirqfd);
void vfio_virqfd_flush_thread(struct virqfd **pvirqfd);
#endif /* VFIO_H */