[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v4 2/2] xen: delay xen_hvm_init_time_ops() if kdump is boot on vcpu>=32
On 3/2/22 7:31 PM, Dongli Zhang wrote: Hi Boris, On 3/2/22 4:20 PM, Boris Ostrovsky wrote:On 3/2/22 11:40 AM, Dongli Zhang wrote:void __init xen_hvm_init_time_ops(void) { + static bool hvm_time_initialized; + + if (hvm_time_initialized) + return; + /* * vector callback is needed otherwise we cannot receive interrupts * on cpu > 0 and at this point we don't know how many cpus are * available. */ if (!xen_have_vector_callback) - return; + goto exit;Why not just return? Do we expect the value of xen_have_vector_callback to change?I just want to keep above sync with ....-borisif (!xen_feature(XENFEAT_hvm_safe_pvclock)) { pr_info("Xen doesn't support pvclock on HVM, disable pv timer"); + goto exit; + }... here. That is, I want the main logic of xen_hvm_init_time_ops() to run for at most once. Both of above two if statements will "go to exit". I didn't notice this actually. I think both of them should return early, there is no reason to set hvm_time_initialized to true when, in fact, we have not initialized anything. And to avoid printing the warning twice we can just replace it with pr_info_once(). I can fix it up when committing so no need to resend. So unless you disagree Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Thank you very much! Dongli Zhang+ + /* + * Only MAX_VIRT_CPUS 'vcpu_info' are embedded inside 'shared_info'. + * The __this_cpu_read(xen_vcpu) is still NULL when Xen HVM guest + * boots on vcpu >= MAX_VIRT_CPUS (e.g., kexec), To access + * __this_cpu_read(xen_vcpu) via xen_clocksource_read() will panic. + * + * The xen_hvm_init_time_ops() should be called again later after + * __this_cpu_read(xen_vcpu) is available. + */ + if (!__this_cpu_read(xen_vcpu)) { + pr_info("Delay xen_init_time_common() as kernel is running on vcpu=%d\n", + xen_vcpu_nr(0)); return; } @@ -577,6 +597,9 @@ void __init xen_hvm_init_time_ops(void) x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents; x86_platform.set_wallclock = xen_set_wallclock; + +exit: + hvm_time_initialized = true; } #endif
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