Messages in this thread Patch in this message | | | From | Zhenzhong Duan <> | Subject | [PATCH RESEND] locking/spinlocks, paravirt, hyperv: Correct the hv_nopvspin case | Date | Wed, 26 Jun 2019 16:56:01 +0800 |
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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@oracle.com> Cc: Waiman Long <longman@redhat.com> Cc: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Sasha Levin <sashal@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: linux-hyperv@vger.kernel.org --- 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..d90b4b0 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 (unlikely(!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)) { -- 1.8.3.1
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