linux-kernel - [PATCH] xen/x86: Don't BUG on CPU0 offlining

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Message-Id: <20170626163930.29697-1-vkuznets@redhat.com>
Date:   Mon, 26 Jun 2017 18:39:30 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     xen-devel@...ts.xenproject.org
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>
Subject: [PATCH] xen/x86: Don't BUG on CPU0 offlining

CONFIG_BOOTPARAM_HOTPLUG_CPU0 allows to offline CPU0 but Xen HVM guests
BUG() in xen_teardown_timer(). Remove the BUG_ON(), this is probably a
leftover from ancient times when CPU0 hotplug was impossible, it works
just fine for HVM.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
- CPU0 hotplug is currently broken on x86, see
  https://lkml.org/lkml/2017/6/26/529
---
 arch/x86/xen/time.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index a1895a8..1ecb05d 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -309,7 +309,6 @@ static irqreturn_t xen_timer_interrupt(int irq, void *dev_id)
 void xen_teardown_timer(int cpu)
 {
 	struct clock_event_device *evt;
-	BUG_ON(cpu == 0);
 	evt = &per_cpu(xen_clock_events, cpu).evt;
 
 	if (evt->irq >= 0) {
-- 
2.9.4