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author | David Woodhouse <dwmw@amazon.co.uk> | 2021-01-13 13:26:02 +0000 |
---|---|---|
committer | Juergen Gross <jgross@suse.com> | 2021-01-13 16:12:00 +0100 |
commit | 3499ba8198cad47b731792e5e56b9ec2a78a83a2 (patch) | |
tree | f2573188a2e7ee7847c1389a9bc8cd15bf5b2484 /drivers/xen/xenbus | |
parent | ef3a575baf53571dc405ee4028e26f50856898e7 (diff) | |
download | linux-3499ba8198cad47b731792e5e56b9ec2a78a83a2.tar.gz linux-3499ba8198cad47b731792e5e56b9ec2a78a83a2.tar.bz2 linux-3499ba8198cad47b731792e5e56b9ec2a78a83a2.zip |
xen: Fix event channel callback via INTX/GSI
For a while, event channel notification via the PCI platform device
has been broken, because we attempt to communicate with xenstore before
we even have notifications working, with the xs_reset_watches() call
in xs_init().
We tend to get away with this on Xen versions below 4.0 because we avoid
calling xs_reset_watches() anyway, because xenstore might not cope with
reading a non-existent key. And newer Xen *does* have the vector
callback support, so we rarely fall back to INTX/GSI delivery.
To fix it, clean up a bit of the mess of xs_init() and xenbus_probe()
startup. Call xs_init() directly from xenbus_init() only in the !XS_HVM
case, deferring it to be called from xenbus_probe() in the XS_HVM case
instead.
Then fix up the invocation of xenbus_probe() to happen either from its
device_initcall if the callback is available early enough, or when the
callback is finally set up. This means that the hack of calling
xenbus_probe() from a workqueue after the first interrupt, or directly
from the PCI platform device setup, is no longer needed.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20210113132606.422794-2-dwmw2@infradead.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Diffstat (limited to 'drivers/xen/xenbus')
-rw-r--r-- | drivers/xen/xenbus/xenbus.h | 1 | ||||
-rw-r--r-- | drivers/xen/xenbus/xenbus_comms.c | 8 | ||||
-rw-r--r-- | drivers/xen/xenbus/xenbus_probe.c | 81 |
3 files changed, 68 insertions, 22 deletions
diff --git a/drivers/xen/xenbus/xenbus.h b/drivers/xen/xenbus/xenbus.h index 2a93b7c9c159..dc1537335414 100644 --- a/drivers/xen/xenbus/xenbus.h +++ b/drivers/xen/xenbus/xenbus.h @@ -115,6 +115,7 @@ int xenbus_probe_node(struct xen_bus_type *bus, const char *type, const char *nodename); int xenbus_probe_devices(struct xen_bus_type *bus); +void xenbus_probe(void); void xenbus_dev_changed(const char *node, struct xen_bus_type *bus); diff --git a/drivers/xen/xenbus/xenbus_comms.c b/drivers/xen/xenbus/xenbus_comms.c index eb5151fc8efa..e5fda0256feb 100644 --- a/drivers/xen/xenbus/xenbus_comms.c +++ b/drivers/xen/xenbus/xenbus_comms.c @@ -57,16 +57,8 @@ DEFINE_MUTEX(xs_response_mutex); static int xenbus_irq; static struct task_struct *xenbus_task; -static DECLARE_WORK(probe_work, xenbus_probe); - - static irqreturn_t wake_waiting(int irq, void *unused) { - if (unlikely(xenstored_ready == 0)) { - xenstored_ready = 1; - schedule_work(&probe_work); - } - wake_up(&xb_waitq); return IRQ_HANDLED; } diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 44634d970a5c..c8f0282bb649 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -683,29 +683,76 @@ void unregister_xenstore_notifier(struct notifier_block *nb) } EXPORT_SYMBOL_GPL(unregister_xenstore_notifier); -void xenbus_probe(struct work_struct *unused) +void xenbus_probe(void) { xenstored_ready = 1; + /* + * In the HVM case, xenbus_init() deferred its call to + * xs_init() in case callbacks were not operational yet. + * So do it now. + */ + if (xen_store_domain_type == XS_HVM) + xs_init(); + /* Notify others that xenstore is up */ blocking_notifier_call_chain(&xenstore_chain, 0, NULL); } -EXPORT_SYMBOL_GPL(xenbus_probe); -static int __init xenbus_probe_initcall(void) +/* + * Returns true when XenStore init must be deferred in order to + * allow the PCI platform device to be initialised, before we + * can actually have event channel interrupts working. + */ +static bool xs_hvm_defer_init_for_callback(void) { - if (!xen_domain()) - return -ENODEV; +#ifdef CONFIG_XEN_PVHVM + return xen_store_domain_type == XS_HVM && + !xen_have_vector_callback; +#else + return false; +#endif +} - if (xen_initial_domain() || xen_hvm_domain()) - return 0; +static int __init xenbus_probe_initcall(void) +{ + /* + * Probe XenBus here in the XS_PV case, and also XS_HVM unless we + * need to wait for the platform PCI device to come up. + */ + if (xen_store_domain_type == XS_PV || + (xen_store_domain_type == XS_HVM && + !xs_hvm_defer_init_for_callback())) + xenbus_probe(); - xenbus_probe(NULL); return 0; } - device_initcall(xenbus_probe_initcall); +int xen_set_callback_via(uint64_t via) +{ + struct xen_hvm_param a; + int ret; + + a.domid = DOMID_SELF; + a.index = HVM_PARAM_CALLBACK_IRQ; + a.value = via; + + ret = HYPERVISOR_hvm_op(HVMOP_set_param, &a); + if (ret) + return ret; + + /* + * If xenbus_probe_initcall() deferred the xenbus_probe() + * due to the callback not functioning yet, we can do it now. + */ + if (!xenstored_ready && xs_hvm_defer_init_for_callback()) + xenbus_probe(); + + return ret; +} +EXPORT_SYMBOL_GPL(xen_set_callback_via); + /* Set up event channel for xenstored which is run as a local process * (this is normally used only in dom0) */ @@ -818,11 +865,17 @@ static int __init xenbus_init(void) break; } - /* Initialize the interface to xenstore. */ - err = xs_init(); - if (err) { - pr_warn("Error initializing xenstore comms: %i\n", err); - goto out_error; + /* + * HVM domains may not have a functional callback yet. In that + * case let xs_init() be called from xenbus_probe(), which will + * get invoked at an appropriate time. + */ + if (xen_store_domain_type != XS_HVM) { + err = xs_init(); + if (err) { + pr_warn("Error initializing xenstore comms: %i\n", err); + goto out_error; + } } if ((xen_store_domain_type != XS_LOCAL) && |