patch-0006-x86-ACPI-re-park-previously-parked-CPUs-upon-resume-.patch

From c2d8f6a77fe7da9d12613729693301265581521b Mon Sep 17 00:00:00 2001
From: Jan Beulich <jbeulich@suse.com>
Date: Fri, 30 Aug 2019 10:24:13 +0200
Subject: [PATCH 6/9] x86/ACPI: re-park previously parked CPUs upon resume from
 S3

Aiui when resuming from S3, CPUs come back out of RESET/INIT. Therefore
they need to undergo the same procedure as was added elsewhere by
commits d8f974f1a6 ("x86: command line option to avoid use of secondary
hyper-threads") and 8797d20a6e ("x86: possibly bring up all CPUs even
if not all are supposed to be used").

Just like done at boot time, avoid (at least pointlessly) using
stop-machine logic.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
(cherry picked from commit eb912011076e76f6c5e4013616a61ba670e7fc15)
---
 xen/common/cpu.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/xen/common/cpu.c b/xen/common/cpu.c
index 8dca74cbb0bd..ecd63aa9a92c 100644
--- a/xen/common/cpu.c
+++ b/xen/common/cpu.c
@@ -110,7 +110,7 @@ int cpu_down(unsigned int cpu)
     if ( err )
         goto fail;
 
-    if ( unlikely(system_state < SYS_STATE_active) )
+    if ( system_state < SYS_STATE_active || system_state == SYS_STATE_resume )
         on_selected_cpus(cpumask_of(cpu), _take_cpu_down, NULL, true);
     else if ( (err = stop_machine_run(take_cpu_down, NULL, cpu)) < 0 )
         goto fail;
@@ -208,15 +208,19 @@ void enable_nonboot_cpus(void)
 
     printk("Enabling non-boot CPUs  ...\n");
 
-    for_each_cpu ( cpu, &frozen_cpus )
+    for_each_present_cpu ( cpu )
     {
+        if ( park_offline_cpus ? cpu == smp_processor_id()
+                               : !cpumask_test_cpu(cpu, &frozen_cpus) )
+            continue;
         if ( (error = cpu_up(cpu)) )
         {
             printk("Error bringing CPU%d up: %d\n", cpu, error);
             BUG_ON(error == -EBUSY);
         }
-        else
-            __cpumask_clear_cpu(cpu, &frozen_cpus);
+        else if ( !__cpumask_test_and_clear_cpu(cpu, &frozen_cpus) &&
+                  (error = cpu_down(cpu)) )
+            printk("Error re-offlining CPU%d: %d\n", cpu, error);
     }
 
     for_each_cpu ( cpu, &frozen_cpus )
-- 
2.26.2