With virt_spin_lock() being guarded by a static key the bare metal case can be optimized by patching the call away completely. In case a kernel running as a guest it can decide whether to use paravitualized spinlocks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior.
V3: - remove test for hypervisor environment from virt_spin_lock(9 as suggested by Waiman Long V2: - use static key instead of making virt_spin_lock() a pvops function Juergen Gross (2): paravirt/locks: use new static key for controlling call of virt_spin_lock() paravirt,xen: correct xen_nopvspin case arch/x86/include/asm/qspinlock.h | 11 ++++++++++- arch/x86/kernel/paravirt-spinlocks.c | 6 ++++++ arch/x86/kernel/smpboot.c | 2 ++ arch/x86/xen/spinlock.c | 2 ++ kernel/locking/qspinlock.c | 4 ++++ 5 files changed, 24 insertions(+), 1 deletion(-) -- 2.12.3 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization