Commit-ID: e6fd28eb3522b31f79a938e24674f77268a120fd
Gitweb: https://git.kernel.org/tip/e6fd28eb3522b31f79a938e24674f77268a120fd
Author: Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Wed, 6 Sep 2017 19:36:25 +0200
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Tue, 10 Oct 2017 11:50:13 +0200
locking/spinlocks, paravirt, xen: Correct the xen_nopvspin case
With the boot parameter "xen_nopvspin" specified a Xen guest should not
make use of paravirt spinlocks, but behave as if running on bare
metal. This is not true, however, as the qspinlock code will fall back
to a test-and-set scheme when it is detecting a hypervisor.
In order to avoid this disable the virt_spin_lock_key.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Waiman Long <longman@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: akataria@xxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: chrisw@xxxxxxxxxxxx
Cc: hpa@xxxxxxxxx
Cc: jeremy@xxxxxxxx
Cc: rusty@xxxxxxxxxxxxxxx
Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20170906173625.18158-3-jgross@xxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/xen/spinlock.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 25a7c43..e8ab80a 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -10,6 +10,7 @@
#include <linux/slab.h>
#include <asm/paravirt.h>
+#include <asm/qspinlock.h>
#include <xen/interface/xen.h>
#include <xen/events.h>
@@ -129,6 +130,7 @@ void __init xen_init_spinlocks(void)
if (!xen_pvspin) {
printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
+ static_branch_disable(&virt_spin_lock_key);
return;
}
printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
--
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