From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72A75C5479D for ; Mon, 9 Jan 2023 16:20:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230013AbjAIQUS (ORCPT ); Mon, 9 Jan 2023 11:20:18 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229643AbjAIQUN (ORCPT ); Mon, 9 Jan 2023 11:20:13 -0500 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B3F61192B9 for ; Mon, 9 Jan 2023 08:20:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=j+Gen2eU0jf9G0iqx+BIbLnHGKCdcFm/8cL1m3LwQjY=; b=j59SI0kNy2I8DmsJs6em3tvKcX IpwD5QTuYugoFRnG4sd6ob+yPyBeJ07//2wTRA8PTlktw8DTcoPAn2MZZtTB2qBaaRDZkrCy1eZ/4 WrhqyrSecJdAZLLysNtj+834ibt9mX0hJFZB23+hh/KRsZ6Ad8U8vaI0DiySGrSRgsgWPdiI6Oucw EoJz+qLRl37m5UVXZqMEiUQruF2HDZeHojZaOcGRvuRQgJFPK+KxgFNyHq2QhYDqjPuaEC/Y186M5 nNxOkp/yp70xZ7lTWP7dMm0y0Tc+OiE9hnpY4ZNKaNRS+/0ZmNJ2PnwSBHJaiIfl8i79beyfHr5vD EGGY44Zw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pEusL-002mH6-34; Mon, 09 Jan 2023 16:19:54 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 5DE00300293; Mon, 9 Jan 2023 17:19:59 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 31BE620086EAB; Mon, 9 Jan 2023 17:19:59 +0100 (CET) Date: Mon, 9 Jan 2023 17:19:59 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , x86@kernel.org Subject: Re: [PATCH x86/nmi 1/2] x86/nmi: Accumulate NMI-progress evidence in exc_nmi() Message-ID: References: <20230105011537.1774941-1-paulmck@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230105011537.1774941-1-paulmck@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 04, 2023 at 05:15:36PM -0800, Paul E. McKenney wrote: > diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c > index cec0bfa3bc04f..4f1651dc65b3a 100644 > --- a/arch/x86/kernel/nmi.c > +++ b/arch/x86/kernel/nmi.c > @@ -69,6 +69,15 @@ struct nmi_stats { > unsigned int unknown; > unsigned int external; > unsigned int swallow; > + unsigned long recv_jiffies; > + unsigned long idt_seq; > + unsigned long idt_nmi_seq; > + unsigned long idt_ignored; > + atomic_long_t idt_calls; > + unsigned long idt_seq_snap; > + unsigned long idt_nmi_seq_snap; > + unsigned long idt_ignored_snap; > + long idt_calls_snap; > }; Urgh, this is more than a whole cacheline of extra data :/ Can't we make this #ifdef CONFIG_NMI_CHECK_CPU ? > @@ -509,8 +526,15 @@ DEFINE_IDTENTRY_RAW(exc_nmi) > > inc_irq_stat(__nmi_count); > > - if (!ignore_nmis) > + if (IS_ENABLED(CONFIG_NMI_CHECK_CPU) && ignore_nmis) { > + WRITE_ONCE(nsp->idt_ignored, nsp->idt_ignored + 1); > + } else if (!ignore_nmis) { > + WRITE_ONCE(nsp->idt_nmi_seq, nsp->idt_nmi_seq + 1); > + WARN_ON_ONCE(!(nsp->idt_nmi_seq & 0x1)); > default_do_nmi(regs); > + WRITE_ONCE(nsp->idt_nmi_seq, nsp->idt_nmi_seq + 1); > + WARN_ON_ONCE(nsp->idt_nmi_seq & 0x1); > + } > > irqentry_nmi_exit(regs, irq_state); That is not a NO-OP when !CONFIG_NMI_CHECK_CPU :/