x86/hyperv: Fix hyperv_pcpu_input_arg handling when CPUs go online/offline

[tomoyo/tomoyo-test1.git] / drivers / hv / hv_common.c

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 64f9cec..542a1d5 100644 (file)
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -364,13 +364,20 @@ int hv_common_cpu_init(unsigned int cpu)
        flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
 
        inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
-       *inputarg = kmalloc(pgcount * HV_HYP_PAGE_SIZE, flags);
-       if (!(*inputarg))
-               return -ENOMEM;
 
-       if (hv_root_partition) {
-               outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
-               *outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
+       /*
+        * hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory is already
+        * allocated if this CPU was previously online and then taken offline
+        */
+       if (!*inputarg) {
+               *inputarg = kmalloc(pgcount * HV_HYP_PAGE_SIZE, flags);
+               if (!(*inputarg))
+                       return -ENOMEM;
+
+               if (hv_root_partition) {
+                       outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
+                       *outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
+               }
        }
 
        msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);
@@ -385,24 +392,17 @@ int hv_common_cpu_init(unsigned int cpu)
 
 int hv_common_cpu_die(unsigned int cpu)
 {
-       unsigned long flags;
-       void **inputarg, **outputarg;
-       void *mem;
-
-       local_irq_save(flags);
-
-       inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
-       mem = *inputarg;
-       *inputarg = NULL;
-
-       if (hv_root_partition) {
-               outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
-               *outputarg = NULL;
-       }
-
-       local_irq_restore(flags);
-
-       kfree(mem);
+       /*
+        * The hyperv_pcpu_input_arg and hyperv_pcpu_output_arg memory
+        * is not freed when the CPU goes offline as the hyperv_pcpu_input_arg
+        * may be used by the Hyper-V vPCI driver in reassigning interrupts
+        * as part of the offlining process.  The interrupt reassignment
+        * happens *after* the CPUHP_AP_HYPERV_ONLINE state has run and
+        * called this function.
+        *
+        * If a previously offlined CPU is brought back online again, the
+        * originally allocated memory is reused in hv_common_cpu_init().
+        */
 
        return 0;
 }