From: Thomas Gleixner Date: Fri, 12 May 2023 21:07:24 +0000 (+0200) Subject: x86/xen/smp_pv: Remove wait for CPU online X-Git-Tag: v6.5-rc1~230^2~28 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2de7fd26d90729c4e3430f9924b199dea810a9bc;p=thirdparty%2Flinux.git x86/xen/smp_pv: Remove wait for CPU online Now that the core code drops sparse_irq_lock after the idle thread synchronized, it's pointless to wait for the AP to mark itself online. Whether the control CPU runs in a wait loop or sleeps in the core code waiting for the online operation to complete makes no difference. Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Tested-by: Michael Kelley Tested-by: Oleksandr Natalenko Tested-by: Helge Deller # parisc Tested-by: Guilherme G. Piccoli # Steam Deck Link: https://lore.kernel.org/r/20230512205256.369512093@linutronix.de --- diff --git a/arch/x86/xen/smp_pv.c b/arch/x86/xen/smp_pv.c index a6f9128a40912..be40927667cf2 100644 --- a/arch/x86/xen/smp_pv.c +++ b/arch/x86/xen/smp_pv.c @@ -340,11 +340,11 @@ static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle) xen_pmu_init(cpu); - rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL); - BUG_ON(rc); - - while (cpu_report_state(cpu) != CPU_ONLINE) - HYPERVISOR_sched_op(SCHEDOP_yield, NULL); + /* + * Why is this a BUG? If the hypercall fails then everything can be + * rolled back, no? + */ + BUG_ON(HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL)); return 0; }