From 2ee432d740436be525d5c62d1e98009fb25b5856 Mon Sep 17 00:00:00 2001
From: Alex Williamson <alex.williamson@redhat.com>
Date: Fri, 8 Mar 2024 16:05:24 -0700
Subject: [PATCH] vfio: Introduce interface to flush virqfd inject workqueue
commit b620ecbd17a03cacd06f014a5d3f3a11285ce053 upstream.
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>
Stable-dep-of: 18c198c96a81 ("vfio/pci: Create persistent INTx handler")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/vfio/virqfd.c | 21 +++++++++++++++++++++
include/linux/vfio.h | 2 ++
2 files changed, 23 insertions(+)
diff --git a/drivers/vfio/virqfd.c b/drivers/vfio/virqfd.c
index 29c564b7a6e1..532269133801 100644
--- a/drivers/vfio/virqfd.c
+++ b/drivers/vfio/virqfd.c
@@ -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);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index a65b2513f8cd..5ac5f182ce0b 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -349,6 +349,7 @@ struct virqfd {
wait_queue_entry_t wait;
poll_table pt;
struct work_struct shutdown;
+ struct work_struct flush_inject;
struct virqfd **pvirqfd;
};
@@ -356,5 +357,6 @@ 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 */