Hi Maintainers, Any further comments on this? Thanks Zhenzhong On 2019/7/3 10:23, Zhenzhong Duan wrote:
With the boot parameter "hv_nopvspin" specified a Hyperv 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. Same change for XEN is already in Commit e6fd28eb3522 ("locking/spinlocks, paravirt, xen: Correct the xen_nopvspin case") Signed-off-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx> Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx> Cc: Sasha Levin <sashal@xxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Waiman Long <longman@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: linux-hyperv@xxxxxxxxxxxxxxx --- v3: remove unlikely() as suggested by Sasha arch/x86/hyperv/hv_spinlock.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c index 07f21a0..210495b 100644 --- a/arch/x86/hyperv/hv_spinlock.c +++ b/arch/x86/hyperv/hv_spinlock.c @@ -64,6 +64,9 @@ __visible bool hv_vcpu_is_preempted(int vcpu)void __init hv_init_spinlocks(void){ + if (!hv_pvspin) + static_branch_disable(&virt_spin_lock_key); + if (!hv_pvspin || !apic || !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) || !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) {
