Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756995AbbGGNpk (ORCPT ); Tue, 7 Jul 2015 09:45:40 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36683 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754439AbbGGNpe (ORCPT ); Tue, 7 Jul 2015 09:45:34 -0400 From: Vitaly Kuznetsov To: Ingo Molnar Cc: x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , linux-kernel@vger.kernel.org, Radim =?utf-8?B?S3LEjW3DocWZ?= , Andrew Jones Subject: Re: [PATCH] x86/irq: hide HYP in /proc/interrupts when not on Xen/Hyper-V References: <1435922834-417-1-git-send-email-vkuznets@redhat.com> <20150704082653.GA13934@gmail.com> <87k2uc16p9.fsf@vitty.brq.redhat.com> <20150707125441.GA20480@gmail.com> Date: Tue, 07 Jul 2015 15:45:30 +0200 In-Reply-To: <20150707125441.GA20480@gmail.com> (Ingo Molnar's message of "Tue, 7 Jul 2015 14:54:42 +0200") Message-ID: <87fv5013ph.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3354 Lines: 85 Ingo Molnar writes: > * Vitaly Kuznetsov wrote: > >> Ingo Molnar writes: >> >> > * Vitaly Kuznetsov wrote: >> > >> >> Hypervisor callback interrupts are only accounted on Xen/Hyper-V and we >> >> detect hypervisor's type in early boot. There is no point in having >> >> always-zero HYP: line on other hypervisors or bare metal. >> >> >> >> Suggested-by: Radim Krčmář >> >> Signed-off-by: Vitaly Kuznetsov >> >> --- >> >> arch/x86/kernel/irq.c | 13 +++++++++---- >> >> 1 file changed, 9 insertions(+), 4 deletions(-) >> >> >> >> diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c >> >> index 88b36648..0c82064 100644 >> >> --- a/arch/x86/kernel/irq.c >> >> +++ b/arch/x86/kernel/irq.c >> >> @@ -18,6 +18,7 @@ >> >> #include >> >> #include >> >> #include >> >> +#include >> >> >> >> #define CREATE_TRACE_POINTS >> >> #include >> >> @@ -139,10 +140,14 @@ int arch_show_interrupts(struct seq_file *p, int prec) >> >> seq_puts(p, " Machine check polls\n"); >> >> #endif >> >> #if IS_ENABLED(CONFIG_HYPERV) || defined(CONFIG_XEN) >> >> - seq_printf(p, "%*s: ", prec, "HYP"); >> >> - for_each_online_cpu(j) >> >> - seq_printf(p, "%10u ", irq_stats(j)->irq_hv_callback_count); >> >> - seq_puts(p, " Hypervisor callback interrupts\n"); >> >> + if (x86_hyper == &x86_hyper_ms_hyperv || >> >> + x86_hyper == &x86_hyper_xen) { >> >> + seq_printf(p, "%*s: ", prec, "HYP"); >> >> + for_each_online_cpu(j) >> >> + seq_printf(p, "%10u ", >> >> + irq_stats(j)->irq_hv_callback_count); >> >> + seq_puts(p, " Hypervisor callback interrupts\n"); >> >> + } >> > >> > So I think we should simplify this to: >> > >> > if (x86_hyper) { >> > ... >> > } >> > >> > this will print the HYP line on hypervisors that don't use >> > HYPERVISOR_CALLBACK_VECTOR, but it will make it a lot more self-maintaining, we >> > won't accidentally skip this line on hypervisors that start using the callback >> > IRQ. >> >> I was under an impression KVM and Vmware don't use these hypervisor >> callback irqs 'by desing' and even if one day they start using it >> someone will have to put inc_irq_stat() somewhere. >> >> If the goal is to avoid having x86_hyper_ms_hyperv/x86_hyper_xen in >> irq.c we can follow Andrew's suggestion and add a flag >> (use_callback_irqs?) to struct hypervisor_x86. > > Yeah, a flag would be nicer, and that flag should also be used somewhere else - > for example in the IRQ vector init code or so? > > I.e. make it only possible to use the callback vector if the flag is set properly > - or something like that. That way there will never be a mismatch between flag and > reality. Actually we already have the flag :-) Both Xen and Hyper-V do alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, ...) so we can simply do test_bit(HYPERVISOR_CALLBACK_VECTOR, used_vectors) here. It feels a little bit hackish but it checks what we need to check. -- Vitaly -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/