x86/xen: Allow to retry if cpu_initialize_context() failed.

If memory allocation in cpu_initialize_context() fails then it will
bring up the VCPU and leave with the corresponding CPU bit set in
xen_cpu_initialized_map.

The following (presumably successful) CPU bring up will BUG in
xen_pv_cpu_up() because nothing for that VCPU would be initialized.

Clear the CPU bits, that were set in cpu_initialize_context() in case
the memory allocation fails.

[ bigeasy: Creating a patch from Boris' email. ]

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220209080214.1439408-2-bigeasy@linutronix.de

diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c
index 688aa8b6ae29a2f57075996ad05788d084b49466..ba7af2eca755b7f08e4fe9a4c31f350defe80c2d 100644 (file)
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -260,8 +260,11 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
                return 0;
 
        ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
-       if (ctxt == NULL)
+       if (ctxt == NULL) {
+               cpumask_clear_cpu(cpu, xen_cpu_initialized_map);
+               cpumask_clear_cpu(cpu, cpu_callout_mask);
                return -ENOMEM;
+       }
 
        gdt = get_cpu_gdt_rw(cpu);