[PATCH 6.1 429/473] drivers/xen: Improve the late XenStore init protocol

Greg Kroah-Hartman
2024-06-06T14:18:59Z

From: Henry Wang <xin.wang2@amd.com>

[ Upstream commit a3607581cd49c17128a486a526a36a97bafcb2bb ]

Currently, the late XenStore init protocol is only triggered properly
for the case that HVM_PARAM_STORE_PFN is ~0ULL (invalid). For the
case that XenStore interface is allocated but not ready (the connection
status is not XENSTORE_CONNECTED), Linux should also wait until the
XenStore is set up properly.

Introduce a macro to describe the XenStore interface is ready, use
it in xenbus_probe_initcall() to select the code path of doing the
late XenStore init protocol or not. Since now we have more than one
condition for XenStore late init, rework the check in xenbus_probe()
for the free_irq().

Take the opportunity to enhance the check of the allocated XenStore
interface can be properly mapped, and return error early if the
memremap() fails.

Fixes: 5b3353949e89 ("xen: add support for initializing xenstore later as HVM domain")
Signed-off-by: Henry Wang <xin.wang2@amd.com>
Signed-off-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Link: https://lore.kernel.org/r/20240517011516.1451087-1-xin.wang2@amd.com
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/xen/xenbus/xenbus_probe.c | 36 ++++++++++++++++++++-----------
1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
index 3205e5d724c8c..1a9ded0cddcb0 100644
--- a/drivers/xen/xenbus/xenbus_probe.c
+++ b/drivers/xen/xenbus/xenbus_probe.c
@@ -65,13 +65,17 @@
#include "xenbus.h"

-static int xs_init_irq;
+static int xs_init_irq = -1;
int xen_store_evtchn;
EXPORT_SYMBOL_GPL(xen_store_evtchn);

struct xenstore_domain_interface *xen_store_interface;
EXPORT_SYMBOL_GPL(xen_store_interface);

+#define XS_INTERFACE_READY \
+ ((xen_store_interface != NULL) && \
+ (xen_store_interface->connection == XENSTORE_CONNECTED))
+
enum xenstore_init xen_store_domain_type;
EXPORT_SYMBOL_GPL(xen_store_domain_type);

@@ -751,19 +755,19 @@ static void xenbus_probe(void)
{
xenstored_ready = 1;

- if (!xen_store_interface) {
+ if (!xen_store_interface)
xen_store_interface = memremap(xen_store_gfn << XEN_PAGE_SHIFT,
XEN_PAGE_SIZE, MEMREMAP_WB);
- /*
- * Now it is safe to free the IRQ used for xenstore late
- * initialization. No need to unbind: it is about to be
- * bound again from xb_init_comms. Note that calling
- * unbind_from_irqhandler now would result in xen_evtchn_close()
- * being called and the event channel not being enabled again
- * afterwards, resulting in missed event notifications.
- */
+ /*
+ * Now it is safe to free the IRQ used for xenstore late
+ * initialization. No need to unbind: it is about to be
+ * bound again from xb_init_comms. Note that calling
+ * unbind_from_irqhandler now would result in xen_evtchn_close()
+ * being called and the event channel not being enabled again
+ * afterwards, resulting in missed event notifications.
+ */
+ if (xs_init_irq >= 0)
free_irq(xs_init_irq, &xb_waitq);
- }

/*
* In the HVM case, xenbus_init() deferred its call to
@@ -822,7 +826,7 @@ static int __init xenbus_probe_initcall(void)
if (xen_store_domain_type == XS_PV ||
(xen_store_domain_type == XS_HVM &&
!xs_hvm_defer_init_for_callback() &&
- xen_store_interface != NULL))
+ XS_INTERFACE_READY))
xenbus_probe();

/*
@@ -831,7 +835,7 @@ static int __init xenbus_probe_initcall(void)
* started, then probe. It will be triggered when communication
* starts happening, by waiting on xb_waitq.
*/
- if (xen_store_domain_type == XS_LOCAL || xen_store_interface == NULL) {
+ if (xen_store_domain_type == XS_LOCAL || !XS_INTERFACE_READY) {
struct task_struct *probe_task;

probe_task = kthread_run(xenbus_probe_thread, NULL,
@@ -1014,6 +1018,12 @@ static int __init xenbus_init(void)
xen_store_interface =
memremap(xen_store_gfn << XEN_PAGE_SHIFT,
XEN_PAGE_SIZE, MEMREMAP_WB);
+ if (!xen_store_interface) {
+ pr_err("%s: cannot map HVM_PARAM_STORE_PFN=%llx\n",
+ __func__, v);
+ err = -EINVAL;
+ goto out_error;
+ }
if (xen_store_interface->connection != XENSTORE_CONNECTED)
wait = true;
}
--
2.43.0