diff mbox series

[v2,3/7] vfio: Introduce interface to flush virqfd inject workqueue

Message ID 20240308230557.805580-4-alex.williamson@redhat.com (mailing list archive)
State New, archived
Headers show
Series vfio: Interrupt eventfd hardening | expand

Commit Message

Alex Williamson March 8, 2024, 11:05 p.m. UTC 
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>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/vfio/virqfd.c | 21 +++++++++++++++++++++
 include/linux/vfio.h  |  2 ++
 2 files changed, 23 insertions(+)

Comments

Eric Auger March 11, 2024, 9:14 a.m. UTC | #1 
On 3/9/24 00:05, Alex Williamson wrote:
> 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>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> ---
>  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 89b265bc6ec3..8b1a29820409 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -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 */
diff mbox series

Patch

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 89b265bc6ec3..8b1a29820409 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -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 */