From b4c9e0ff16a0442bbd8d6871e36eee6bdb0a1be6 Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Mon, 1 Feb 2021 14:57:06 +0100 Subject: [PATCH] 4.14-stable patches added patches: xen-fix-xenstore-initialisation-for-xs_local.patch --- queue-4.14/series | 1 + ...xenstore-initialisation-for-xs_local.patch | 92 +++++++++++++++++++ 2 files changed, 93 insertions(+) create mode 100644 queue-4.14/xen-fix-xenstore-initialisation-for-xs_local.patch diff --git a/queue-4.14/series b/queue-4.14/series index dca2d3f91ea..a1ae0b91f12 100644 --- a/queue-4.14/series +++ b/queue-4.14/series @@ -7,3 +7,4 @@ drivers-soc-atmel-avoid-calling-at91_soc_init-on-non-at91-socs.patch drivers-soc-atmel-add-null-entry-at-the-end-of-at91_soc_allowed_list.patch kvm-x86-pmu-fix-hw_ref_cpu_cycles-event-pseudo-encoding-in-intel_arch_events.patch kvm-x86-get-smi-pending-status-correctly.patch +xen-fix-xenstore-initialisation-for-xs_local.patch diff --git a/queue-4.14/xen-fix-xenstore-initialisation-for-xs_local.patch b/queue-4.14/xen-fix-xenstore-initialisation-for-xs_local.patch new file mode 100644 index 00000000000..47024ab7ba9 --- /dev/null +++ b/queue-4.14/xen-fix-xenstore-initialisation-for-xs_local.patch @@ -0,0 +1,92 @@ +From 5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1 Mon Sep 17 00:00:00 2001 +From: David Woodhouse +Date: Tue, 26 Jan 2021 17:01:49 +0000 +Subject: xen: Fix XenStore initialisation for XS_LOCAL + +From: David Woodhouse + +commit 5f46400f7a6a4fad635d5a79e2aa5a04a30ffea1 upstream. + +In commit 3499ba8198ca ("xen: Fix event channel callback via INTX/GSI") +I reworked the triggering of xenbus_probe(). + +I tried to simplify things by taking out the workqueue based startup +triggered from wake_waiting(); the somewhat poorly named xenbus IRQ +handler. + +I missed the fact that in the XS_LOCAL case (Dom0 starting its own +xenstored or xenstore-stubdom, which happens after the kernel is booted +completely), that IRQ-based trigger is still actually needed. + +So... put it back, except more cleanly. By just spawning a xenbus_probe +thread which waits on xb_waitq and runs the probe the first time it +gets woken, just as the workqueue-based hack did. + +This is actually a nicer approach for *all* the back ends with different +interrupt methods, and we can switch them all over to that without the +complex conditions for when to trigger it. But not in -rc6. This is +the minimal fix for the regression, although it's a step in the right +direction instead of doing a partial revert and actually putting the +workqueue back. It's also simpler than the workqueue. + +Fixes: 3499ba8198ca ("xen: Fix event channel callback via INTX/GSI") +Reported-by: Juergen Gross +Signed-off-by: David Woodhouse +Reviewed-by: Juergen Gross +Link: https://lore.kernel.org/r/4c9af052a6e0f6485d1de43f2c38b1461996db99.camel@infradead.org +Signed-off-by: Juergen Gross +Cc: Salvatore Bonaccorso +Cc: Jason Andryuk +Signed-off-by: Greg Kroah-Hartman + +--- + drivers/xen/xenbus/xenbus_probe.c | 31 +++++++++++++++++++++++++++++++ + 1 file changed, 31 insertions(+) + +--- a/drivers/xen/xenbus/xenbus_probe.c ++++ b/drivers/xen/xenbus/xenbus_probe.c +@@ -705,6 +705,23 @@ static bool xs_hvm_defer_init_for_callba + #endif + } + ++static int xenbus_probe_thread(void *unused) ++{ ++ DEFINE_WAIT(w); ++ ++ /* ++ * We actually just want to wait for *any* trigger of xb_waitq, ++ * and run xenbus_probe() the moment it occurs. ++ */ ++ prepare_to_wait(&xb_waitq, &w, TASK_INTERRUPTIBLE); ++ schedule(); ++ finish_wait(&xb_waitq, &w); ++ ++ DPRINTK("probing"); ++ xenbus_probe(); ++ return 0; ++} ++ + static int __init xenbus_probe_initcall(void) + { + /* +@@ -716,6 +733,20 @@ static int __init xenbus_probe_initcall( + !xs_hvm_defer_init_for_callback())) + xenbus_probe(); + ++ /* ++ * For XS_LOCAL, spawn a thread which will wait for xenstored ++ * or a xenstore-stubdom to be started, then probe. It will be ++ * triggered when communication starts happening, by waiting ++ * on xb_waitq. ++ */ ++ if (xen_store_domain_type == XS_LOCAL) { ++ struct task_struct *probe_task; ++ ++ probe_task = kthread_run(xenbus_probe_thread, NULL, ++ "xenbus_probe"); ++ if (IS_ERR(probe_task)) ++ return PTR_ERR(probe_task); ++ } + return 0; + } + device_initcall(xenbus_probe_initcall); -- 2.47.3