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=-12.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 84531C388F7 for ; Thu, 22 Oct 2020 22:26:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3363824631 for ; Thu, 22 Oct 2020 22:26:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S372781AbgJVW0e convert rfc822-to-8bit (ORCPT ); Thu, 22 Oct 2020 18:26:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:51666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S372778AbgJVW0d (ORCPT ); Thu, 22 Oct 2020 18:26:33 -0400 From: bugzilla-daemon@bugzilla.kernel.org To: kvm@vger.kernel.org Subject: [Bug 209253] Loss of connectivity on guest after important host <-> guest traffic Date: Thu, 22 Oct 2020 22:26:32 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: AssignedTo virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Product: Virtualization X-Bugzilla-Component: kvm X-Bugzilla-Version: unspecified X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: arequipeno@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: virtualization_kvm@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=209253 --- Comment #5 from Ian Pilcher (arequipeno@gmail.com) --- Based on my git bisect, it looks like this commit is triggering the WARNING. commit c49fa6397b6d29ce10c0ae5b2528bb004a14691f Author: Alex Williamson Date: Mon Aug 17 11:08:18 2020 -0600 vfio-pci: Avoid recursive read-lock usage [ Upstream commit bc93b9ae0151ae5ad5b8504cdc598428ea99570b ] A down_read on memory_lock is held when performing read/write accesses to MMIO BAR space, including across the copy_to/from_user() callouts which may fault. If the user buffer for these copies resides in an mmap of device MMIO space, the mmap fault handler will acquire a recursive read-lock on memory_lock. Avoid this by reducing the lock granularity. Sequential accesses requiring multiple ioread/iowrite cycles are expected to be rare, therefore typical accesses should not see additional overhead. VGA MMIO accesses are expected to be non-fatal regardless of the PCI memory enable bit to allow legacy probing, this behavior remains with a comment added. ioeventfds are now included in memory access testing, with writes dropped while memory space is disabled. Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory") Reported-by: Zhiyi Guo Tested-by: Zhiyi Guo Reviewed-by: Cornelia Huck Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin drivers/vfio/pci/vfio_pci_private.h | 2 + drivers/vfio/pci/vfio_pci_rdwr.c | 120 ++++++++++++++++++++++++++++-------- 2 files changed, 98 insertions(+), 24 deletions(-) https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bc93b9ae0151ae5ad5b8504cdc598428ea99570b -- You are receiving this mail because: You are watching the assignee of the bug.