1 files changed, 99 insertions, 0 deletions

diff --git a/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.17/0094-xen-smp-Fix-crash-when-booting-with-ACPI-hotplug-CPU.patch b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.17/0094-xen-smp-Fix-crash-when-booting-with-ACPI-hotplug-CPU.patch
new file mode 100644
index 00000000..02b157fc
--- /dev/null
+++ b/recipes-kernel/linux/linux-ti33x-psp-3.2/3.2.17/0094-xen-smp-Fix-crash-when-booting-with-ACPI-hotplug-CPU.patch
@@ -0,0 +1,99 @@
+From 7e7b9fb05d7e36d2d585a422de52c3b2e3345cdf Mon Sep 17 00:00:00 2001
+From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Date: Thu, 26 Apr 2012 13:50:03 -0400
+Subject: [PATCH 094/165] xen/smp: Fix crash when booting with ACPI hotplug
+ CPUs.
+
+commit cf405ae612b0f7e2358db7ff594c0e94846137aa upstream.
+
+When we boot on a machine that can hotplug CPUs and we
+are using 'dom0_max_vcpus=X' on the Xen hypervisor line
+to clip the amount of CPUs available to the initial domain,
+we get this:
+
+(XEN) Command line: com1=115200,8n1 dom0_mem=8G noreboot dom0_max_vcpus=8 sync_console mce_verbosity=verbose console=com1,vga loglvl=all guest_loglvl=all
+.. snip..
+DMI: Intel Corporation S2600CP/S2600CP, BIOS SE5C600.86B.99.99.x032.072520111118 07/25/2011
+.. snip.
+SMP: Allowing 64 CPUs, 32 hotplug CPUs
+installing Xen timer for CPU 7
+cpu 7 spinlock event irq 361
+NMI watchdog: disabled (cpu7): hardware events not enabled
+Brought up 8 CPUs
+.. snip..
+        [acpi processor finds the CPUs are not initialized and starts calling
+        arch_register_cpu, which creates /sys/devices/system/cpu/cpu8/online]
+CPU 8 got hotplugged
+CPU 9 got hotplugged
+CPU 10 got hotplugged
+.. snip..
+initcall 1_acpi_battery_init_async+0x0/0x1b returned 0 after 406 usecs
+calling  erst_init+0x0/0x2bb @ 1
+
+        [and the scheduler sticks newly started tasks on the new CPUs, but
+        said CPUs cannot be initialized b/c the hypervisor has limited the
+        amount of vCPUS to 8 - as per the dom0_max_vcpus=8 flag.
+        The spinlock tries to kick the other CPU, but the structure for that
+        is not initialized and we crash.]
+BUG: unable to handle kernel paging request at fffffffffffffed8
+IP: [<ffffffff81035289>] xen_spin_lock+0x29/0x60
+PGD 180d067 PUD 180e067 PMD 0
+Oops: 0002 [#1] SMP
+CPU 7
+Modules linked in:
+
+Pid: 1, comm: swapper/0 Not tainted 3.4.0-rc2upstream-00001-gf5154e8 #1 Intel Corporation S2600CP/S2600CP
+RIP: e030:[<ffffffff81035289>]  [<ffffffff81035289>] xen_spin_lock+0x29/0x60
+RSP: e02b:ffff8801fb9b3a70  EFLAGS: 00010282
+
+With this patch, we cap the amount of vCPUS that the initial domain
+can run, to exactly what dom0_max_vcpus=X has specified.
+
+In the future, if there is a hypercall that will allow a running
+domain to expand past its initial set of vCPUS, this patch should
+be re-evaluated.
+
+Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
+---
+ arch/x86/xen/smp.c |   15 +++++++++++++++
+ 1 files changed, 15 insertions(+), 0 deletions(-)
+
+diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
+index 041d4fe..9a23fff 100644
+--- a/arch/x86/xen/smp.c
++++ b/arch/x86/xen/smp.c
+@@ -172,6 +172,7 @@ static void __init xen_fill_possible_map(void)
+ static void __init xen_filter_cpu_maps(void)
+ {
+        int i, rc;
++       unsigned int subtract = 0;
+ 
+        if (!xen_initial_domain())
+                return;
+@@ -186,8 +187,22 @@ static void __init xen_filter_cpu_maps(void)
+                } else {
+                        set_cpu_possible(i, false);
+                        set_cpu_present(i, false);
++                       subtract++;
+                }
+        }
++#ifdef CONFIG_HOTPLUG_CPU
++       /* This is akin to using 'nr_cpus' on the Linux command line.
++        * Which is OK as when we use 'dom0_max_vcpus=X' we can only
++        * have up to X, while nr_cpu_ids is greater than X. This
++        * normally is not a problem, except when CPU hotplugging
++        * is involved and then there might be more than X CPUs
++        * in the guest - which will not work as there is no
++        * hypercall to expand the max number of VCPUs an already
++        * running guest has. So cap it up to X. */
++       if (subtract)
++               nr_cpu_ids = nr_cpu_ids - subtract;
++#endif
++
+ }
+ 
+ static void __init xen_smp_prepare_boot_cpu(void)
+-- 
+1.7.7.6
+