[PATCH v2 1/2] arm-autonomy: Fix XenStore initialisation for host kernels < 5.10.13

* [PATCH v2 1/2] arm-autonomy: Fix XenStore initialisation for host kernels < 5.10.13
@ 2021-02-18 16:09 Diego Sueiro
  2021-02-18 16:10 ` [PATCH v2 2/2] arm-autonomy: Fix xenbus probe for guest kernels < 5.10.17 Diego Sueiro
  0 siblings, 1 reply; 2+ messages in thread
From: Diego Sueiro @ 2021-02-18 16:09 UTC (permalink / raw)
  To: meta-arm; +Cc: nd

The arm-autonomy-host kernels older than 5.10.13 need to backport the
0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch in order to be able to
use the `xl block-attach` and fix this issue:
```
xl block-attach 0 "phy:/dev/vg-xen-vda3/base" xvda w
libxl: error: libxl_xshelp.c:201:libxl__xs_read_mandatory: xenstore read failed: `/libxl/0/type': No such file or directory
libxl: warning: libxl_dom.c:52:libxl__domain_type: unable to get domain type for domid=0, assuming HVM
libxl: error: libxl_disk.c:314:device_disk_add: device already exists in xenstore
libxl: error: libxl_device.c:1407:device_addrm_aocomplete: unable to add device
```

This issue is not present in linux-linaro-arm[-rt] 5.4.0 used by N1SDP, hence
we do not apply this patch for it.

Issue-Id: SCM-2151
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Change-Id: I1a38e22084161fb4b6028ef12443707cc566d56e
---
 ...XenStore-initialisation-for-XS_LOCAL.patch | 98 +++++++++++++++++++
 .../linux/linux-arm-autonomy.inc              |  7 ++
 2 files changed, 105 insertions(+)
 create mode 100644 meta-arm-autonomy/recipes-kernel/linux/files/0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch

diff --git a/meta-arm-autonomy/recipes-kernel/linux/files/0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch b/meta-arm-autonomy/recipes-kernel/linux/files/0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch
new file mode 100644
index 0000000..5bf9b74
--- /dev/null
+++ b/meta-arm-autonomy/recipes-kernel/linux/files/0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch
@@ -0,0 +1,98 @@
+From 5f3d54c00f1f2682cee9c590c22655b0330ffd18 Mon Sep 17 00:00:00 2001
+Message-Id: <5f3d54c00f1f2682cee9c590c22655b0330ffd18.1612780458.git.diego.sueiro@arm.com>
+From: David Woodhouse <dwmw@amazon.co.uk>
+Date: Tue, 26 Jan 2021 17:01:49 +0000
+Subject: [PATCH] xen: Fix XenStore initialisation for XS_LOCAL
+
+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 <jgross@suse.com>
+Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
+Reviewed-by: Juergen Gross <jgross@suse.com>
+Link: https://lore.kernel.org/r/4c9af052a6e0f6485d1de43f2c38b1461996db99.camel@infradead.org
+Signed-off-by: Juergen Gross <jgross@suse.com>
+Cc: Salvatore Bonaccorso <carnil@debian.org>
+Cc: Jason Andryuk <jandryuk@gmail.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+Upstream-Status: Backport
+Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
+---
+ drivers/xen/xenbus/xenbus_probe.c | 31 +++++++++++++++++++++++++++++++
+ 1 file changed, 31 insertions(+)
+
+diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c
+index c8f0282bb649..18ffd0551b54 100644
+--- a/drivers/xen/xenbus/xenbus_probe.c
++++ b/drivers/xen/xenbus/xenbus_probe.c
+@@ -714,6 +714,23 @@ static bool xs_hvm_defer_init_for_callback(void)
+ #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)
+ {
+ 	/*
+@@ -725,6 +742,20 @@ static int __init xenbus_probe_initcall(void)
+ 	     !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);
+-- 
+2.17.1
+
diff --git a/meta-arm-autonomy/recipes-kernel/linux/linux-arm-autonomy.inc b/meta-arm-autonomy/recipes-kernel/linux/linux-arm-autonomy.inc
index 89c9fce..e14ea96 100644
--- a/meta-arm-autonomy/recipes-kernel/linux/linux-arm-autonomy.inc
+++ b/meta-arm-autonomy/recipes-kernel/linux/linux-arm-autonomy.inc
@@ -38,8 +38,15 @@ python() {
     from distutils.version import LooseVersion
 
     kernelVersion = d.getVar('LINUX_VERSION')
+    pn = d.getVar('PN')
 
     if kernelVersion and LooseVersion(kernelVersion) < '5.10':
         if oe.utils.any_distro_features(d, "arm-autonomy-host arm-autonomy-guest"):
             d.appendVar('SRC_URI', ' file://files/0001-xen-arm-do-not-setup-the-runstate-info-page-if-kpti-.patch' )
+
+    if kernelVersion and LooseVersion(kernelVersion) < '5.10.13' \
+       and pn != 'linux-libc-headers' \
+       and not pn.startswith('linux-linaro-arm') \
+       and oe.utils.any_distro_features(d, "arm-autonomy-host"):
+        d.appendVar('SRC_URI', ' file://files/0001-xen-Fix-XenStore-initialisation-for-XS_LOCAL.patch' )
 }
-- 
2.17.1


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