Messages in this thread Patch in this message | | | Date | Tue, 10 Oct 2017 04:03:32 -0700 | From | tip-bot for Juergen Gross <> | Subject | [tip:locking/core] locking/spinlocks, paravirt, xen: Correct the xen_nopvspin case |
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Commit-ID: e6fd28eb3522b31f79a938e24674f77268a120fd Gitweb: https://git.kernel.org/tip/e6fd28eb3522b31f79a938e24674f77268a120fd Author: Juergen Gross <jgross@suse.com> AuthorDate: Wed, 6 Sep 2017 19:36:25 +0200 Committer: Ingo Molnar <mingo@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 <jgross@suse.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Waiman Long <longman@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akataria@vmware.com Cc: boris.ostrovsky@oracle.com Cc: chrisw@sous-sol.org Cc: hpa@zytor.com Cc: jeremy@goop.org Cc: rusty@rustcorp.com.au Cc: virtualization@lists.linux-foundation.org Cc: xen-devel@lists.xenproject.org Link: http://lkml.kernel.org/r/20170906173625.18158-3-jgross@suse.com Signed-off-by: Ingo Molnar <mingo@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");
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