From owner-svn-src-stable-12@freebsd.org Fri Oct 23 12:27:34 2020 Return-Path: Delivered-To: svn-src-stable-12@mailman.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.nyi.freebsd.org (Postfix) with ESMTP id 0E52B445E11; Fri, 23 Oct 2020 12:27:34 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from kib.kiev.ua (kib.kiev.ua [IPv6:2001:470:d5e7:1::1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4CHk5K3p4Kz44Nw; Fri, 23 Oct 2020 12:27:33 +0000 (UTC) (envelope-from kostikbel@gmail.com) Received: from tom.home (kib@localhost [127.0.0.1]) by kib.kiev.ua (8.16.1/8.16.1) with ESMTPS id 09NCRQwv028234 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Fri, 23 Oct 2020 15:27:29 +0300 (EEST) (envelope-from kostikbel@gmail.com) DKIM-Filter: OpenDKIM Filter v2.10.3 kib.kiev.ua 09NCRQwv028234 Received: (from kostik@localhost) by tom.home (8.16.1/8.16.1/Submit) id 09NCRQS5028233; Fri, 23 Oct 2020 15:27:26 +0300 (EEST) (envelope-from kostikbel@gmail.com) X-Authentication-Warning: tom.home: kostik set sender to kostikbel@gmail.com using -f Date: Fri, 23 Oct 2020 15:27:26 +0300 From: Konstantin Belousov To: Ryan Moeller Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-12@freebsd.org Subject: Re: svn commit: r366965 - stable/12/usr.sbin/bhyve Message-ID: <20201023122726.GZ2643@kib.kiev.ua> References: <202010231048.09NAmEW8090391@repo.freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202010231048.09NAmEW8090391@repo.freebsd.org> X-Spam-Status: No, score=-1.0 required=5.0 tests=ALL_TRUSTED,BAYES_00, DKIM_ADSP_CUSTOM_MED,FORGED_GMAIL_RCVD,FREEMAIL_FROM, NML_ADSP_CUSTOM_MED autolearn=no autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on tom.home X-Rspamd-Queue-Id: 4CHk5K3p4Kz44Nw X-Spamd-Bar: ---- Authentication-Results: mx1.freebsd.org; none X-Spamd-Result: default: False [-4.00 / 15.00]; REPLY(-4.00)[]; ASN(0.00)[asn:6939, ipnet:2001:470::/32, country:US] X-BeenThere: svn-src-stable-12@freebsd.org X-Mailman-Version: 2.1.33 Precedence: list List-Id: SVN commit messages for only the 12-stable src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Oct 2020 12:27:34 -0000 On Fri, Oct 23, 2020 at 10:48:14AM +0000, Ryan Moeller wrote: > Author: freqlabs > Date: Fri Oct 23 10:48:14 2020 > New Revision: 366965 > URL: https://svnweb.freebsd.org/changeset/base/366965 > > Log: > MFC r366771: > > bhyve: Update TX descriptor base address and host mapping on change > > bhyve sometimes segfaults when using an e1000 NIC with a Windows guest. > > We are only updating our tdba and cached host mapping when the low address > register is written and when tx is set enabled, but not when the high address > or length registers are written. It is observed that Windows 10 is occasionally > enabling tx first then writing the registers in the order low, high, len. This > leaves us with a bogus base address and mapping, which causes a segfault later > when we try to copy from a descriptor that has unpredictable garbage in a > pointer. > > Updating the address and mapping when any of those registers change seems to fix > that particular issue. Does this description mean that if guest writes garbage into base, it can crash monitor ?