Commit-ID: e6fd28eb3522b31f79a938e24674f77268a120fd Gitweb: https://git.kernel.org/tip/e6fd28eb3522b31f79a938e24674f77268a120fd Author: Juergen Gross <jgr...@suse.com> AuthorDate: Wed, 6 Sep 2017 19:36:25 +0200 Committer: Ingo Molnar <mi...@kernel.org> 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 <jgr...@suse.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Acked-by: Waiman Long <long...@redhat.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: akata...@vmware.com Cc: boris.ostrov...@oracle.com Cc: chr...@sous-sol.org Cc: h...@zytor.com Cc: jer...@goop.org Cc: ru...@rustcorp.com.au Cc: virtualizat...@lists.linux-foundation.org Cc: xen-de...@lists.xenproject.org Link: http://lkml.kernel.org/r/20170906173625.18158-3-jgr...@suse.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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");
