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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3483DC43613 for ; Mon, 24 Jun 2019 10:09:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0DBF12063F for ; Mon, 24 Jun 2019 10:09:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730537AbfFXKJo (ORCPT ); Mon, 24 Jun 2019 06:09:44 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:35542 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728434AbfFXKJg (ORCPT ); Mon, 24 Jun 2019 06:09:36 -0400 Received: from p5b06daab.dip0.t-ipconnect.de ([91.6.218.171] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1hfLuj-0005CU-L6; Mon, 24 Jun 2019 12:09:29 +0200 Date: Mon, 24 Jun 2019 12:09:28 +0200 (CEST) From: Thomas Gleixner To: Jan Kiszka cc: Ingo Molnar , Borislav Petkov , x86@kernel.org, Linux Kernel Mailing List Subject: Re: x86: Spurious vectors not handled robustly In-Reply-To: Message-ID: References: User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Jan, On Mon, 24 Jun 2019, Jan Kiszka wrote: > probably since "x86: Avoid building unused IRQ entry stubs" (2414e021ac8d), > the kernel can no longer tell spurious IRQs by the APIC apart from spuriously > triggered unused vectors. Err. It does. > We've managed to trigger such a cause with the Jailhouse hypervisor > (incorrectly injected MANAGED_IRQ_SHUTDOWN_VECTOR), and the result was > not only a misreport of the vector number (0xff instead of 0xef - took me > a while...), but also stalled interrupts of equal and lower priority > because a spurious interrupt is not (and must not be) acknowledged. That does not make sense. __visible void __irq_entry smp_spurious_interrupt(struct pt_regs *regs) { u8 vector = ~regs->orig_ax; u32 v; entering_irq(); trace_spurious_apic_entry(vector); /* * Check if this really is a spurious interrupt and ACK it * if it is a vectored one. Just in case... */ v = apic_read(APIC_ISR + ((vector & ~0x1f) >> 1)); if (v & (1 << (vector & 0x1f))) ack_APIC_irq(); If it is a vectored one it _IS_ acked. inc_irq_stat(irq_spurious_count); /* see sw-dev-man vol 3, chapter 7.4.13.5 */ pr_info("spurious APIC interrupt through vector %02x on CPU#%d, " "should never happen.\n", vector, smp_processor_id()); and the vector through which that comes is printed correctly, unless regs->orig_ax is hosed. Thanks, tglx