On 29.06.23 18:46, Rahul Singh wrote:
Hello Rahul
> Xen 4.17 supports the creation of static evtchns. To allow user space
> application to bind static evtchns introduce new ioctl
> "IOCTL_EVTCHN_BIND_STATIC". Existing IOCTL doing more than binding
> that’s why we need to introduce the new IOCTL to only bind the static
> event channels.
>
> Also, static evtchns to be available for use during the lifetime of the
> guest. When the application exits, __unbind_from_irq() ends up being
> called from release() file operations because of that static evtchns
> are getting closed. To avoid closing the static event channel, add the
> new bool variable "is_static" in "struct irq_info" to mark the event
> channel static when creating the event channel to avoid closing the
> static evtchn.
>
> Signed-off-by: Rahul Singh <rahul.si...@arm.com>
> ---
> v2:
> * Use bool in place u8 to define is_static variable.
> * Avoid closing the static evtchns in error path.
Patch looks good to me, just a nit (question) below.
> ---
> drivers/xen/events/events_base.c | 7 +++++--
> drivers/xen/evtchn.c | 30 ++++++++++++++++++++++--------
> include/uapi/xen/evtchn.h | 9 +++++++++
> include/xen/events.h | 2 +-
> 4 files changed, 37 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/xen/events/events_base.c
> b/drivers/xen/events/events_base.c
> index c7715f8bd452..5d3b5c7cfe64 100644
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -112,6 +112,7 @@ struct irq_info {
> unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */
> u64 eoi_time; /* Time in jiffies when to EOI. */
> raw_spinlock_t lock;
> + bool is_static; /* Is event channel static */
>
> union {
> unsigned short virq;
> @@ -982,7 +983,8 @@ static void __unbind_from_irq(unsigned int irq)
> unsigned int cpu = cpu_from_irq(irq);
> struct xenbus_device *dev;
>
> - xen_evtchn_close(evtchn);
> + if (!info->is_static)
> + xen_evtchn_close(evtchn);
>
> switch (type_from_irq(irq)) {
> case IRQT_VIRQ:
> @@ -1574,7 +1576,7 @@ int xen_set_irq_priority(unsigned irq, unsigned
> priority)
> }
> EXPORT_SYMBOL_GPL(xen_set_irq_priority);
>
> -int evtchn_make_refcounted(evtchn_port_t evtchn)
> +int evtchn_make_refcounted(evtchn_port_t evtchn, bool is_static)
> {
> int irq = get_evtchn_to_irq(evtchn);
> struct irq_info *info;
> @@ -1590,6 +1592,7 @@ int evtchn_make_refcounted(evtchn_port_t evtchn)
> WARN_ON(info->refcnt != -1);
>
> info->refcnt = 1;
> + info->is_static = is_static;
>
> return 0;
> }
> diff --git a/drivers/xen/evtchn.c b/drivers/xen/evtchn.c
> index c99415a70051..e6d2303478b2 100644
> --- a/drivers/xen/evtchn.c
> +++ b/drivers/xen/evtchn.c
> @@ -366,7 +366,8 @@ static int evtchn_resize_ring(struct per_user_data *u)
> return 0;
> }
>
> -static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port)
> +static int evtchn_bind_to_user(struct per_user_data *u, evtchn_port_t port,
> + bool is_static)
> {
> struct user_evtchn *evtchn;
> struct evtchn_close close;
> @@ -402,14 +403,16 @@ static int evtchn_bind_to_user(struct per_user_data *u,
> evtchn_port_t port)
> if (rc < 0)
> goto err;
>
> - rc = evtchn_make_refcounted(port);
> + rc = evtchn_make_refcounted(port, is_static);
> return rc;
>
> err:
> /* bind failed, should close the port now */
> - close.port = port;
> - if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
> - BUG();
> + if (!is_static) {
I think now "struct evtchn_close close;" can be placed here as it is not
used outside of this block.
Also this block looks like an open-coded version of xen_evtchn_close()
defined at events_base.c, so maybe it is worth making xen_evtchn_close()
static inline and placing it into events.h, then calling helper here?
Please note, I will be ok either way.
> + close.port = port;
> + if (HYPERVISOR_event_channel_op(EVTCHNOP_close, &close) != 0)
> + BUG();
> + }
> del_evtchn(u, evtchn);
> return rc;
> }
[snip]
