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=-3.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 98BEBC3A5A4 for ; Sun, 1 Sep 2019 18:41:40 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4DCDE2190F for ; Sun, 1 Sep 2019 18:41:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (4096-bit key) header.d=crudebyte.com header.i=@crudebyte.com header.b="a+X0eLDl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4DCDE2190F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=nongnu.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59726 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i4UnD-0000Xu-DD for qemu-devel@archiver.kernel.org; Sun, 01 Sep 2019 14:41:39 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:43940) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i4UmH-0008LI-Se for qemu-devel@nongnu.org; Sun, 01 Sep 2019 14:40:44 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i4UmF-0001DJ-Jl for qemu-devel@nongnu.org; Sun, 01 Sep 2019 14:40:41 -0400 Received: from kylie.crudebyte.com ([5.189.157.229]:58471) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i4UmF-0001CV-1A for qemu-devel@nongnu.org; Sun, 01 Sep 2019 14:40:39 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=crudebyte.com; s=kylie; h=Content-Type:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=MFVO1g2zl/2X8RHBCkyneaYCo1HojVcpqvQeE02e9OY=; b=a+X0eLDlP+s9UVGlczwL/ZBbdx 1oLYqoY4SJeC3UBMqHowehyldS0TJ6G+Zv+4FGSWCT5/uGlw2oRwrfW5JbL5Zx98XSPr6COhRk4P0 jHgdey1Mb7w5sHkwaH4NFcCNOfaQ7oOAebFNYkmd29ZBqFfRJ7utsUGp24Gj0OHktpCKAqYOk2Wyg Sgk1AC/pzfNmxDNKIdEvYbTF13kLL0ML4QOgIAyIoK0jQnuPpeCWIEzRGZJdDFBpNaibGFfKxzQGX GWdONUWtec/xUsuQumOAYw/1vRpNAy8qIdIlKEHuBn6Q7nqrX7gslr9MIL02YeEEgJ0s4TKJ4aq3f 2Ut9knEne1wFCa6LGKKxELQWAqbGuBuKRLOKo2hjY4h/f9MwS7HXL33wKY8Z2ZSKa8XWnxN+ihSIO SW0SD86WLpx54DMJZMhbWeUyom4NWPWIvzFrzpGL88o/UgYfuBgT4KghjJlDeE8jo+XoOoLfprz8t V0qVmN6n3Nm3RwNB3+juBOvFfiTUroWpk3Z04qtw7L5DhVkEA7q9NjeozN9lFJxWImHT5h19w/Pfi JFAa+TDCrJhIUScR6ocPx35VtRx2TZCJa+ZR8t56Qwi+ux6EurNN/tX1lQGegQC/yIzJd4tqf5pqg 6TYPE/rNbmZYJhrC6PMAQ0eVLoZ5BFNKreJb4/o1I=; To: qemu-devel@nongnu.org Date: Sun, 01 Sep 2019 20:40:34 +0200 Message-ID: <2018575.EFrLczUYWK@silver> In-Reply-To: <20190829185528.1db6607e@bahia.lan> References: <50fc6fbbfd80c25d2ad1752fb945cdfc7d847f20.1566503584.git.qemu_oss@crudebyte.com> <20190829185528.1db6607e@bahia.lan> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 5.189.157.229 Subject: Re: [Qemu-devel] [PATCH v6 2/4] 9p: Added virtfs option 'multidevs=remap|forbid|warn' X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Christian Schoenebeck via Qemu-devel Reply-To: Christian Schoenebeck Cc: Daniel =?ISO-8859-1?Q?P=2E_Berrang=E9?= , Stefan Hajnoczi , Christian Schoenebeck , Greg Kurz , "Dr. David Alan Gilbert" , Antonios Motakis Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Donnerstag, 29. August 2019 18:55:28 CEST Greg Kurz wrote: > > diff --git a/fsdev/qemu-fsdev-opts.c b/fsdev/qemu-fsdev-opts.c > > index 7c31ffffaf..07a18c6e48 100644 > > --- a/fsdev/qemu-fsdev-opts.c > > +++ b/fsdev/qemu-fsdev-opts.c > > @@ -31,7 +31,9 @@ static QemuOptsList qemu_fsdev_opts =3D { > >=20 > > }, { > > =20 > > .name =3D "readonly", > > .type =3D QEMU_OPT_BOOL, > >=20 > > - > > + }, { > > + .name =3D "multidevs", > > + .type =3D QEMU_OPT_STRING, > >=20 > > }, { > > =20 > > .name =3D "socket", > > .type =3D QEMU_OPT_STRING, > >=20 > > @@ -76,6 +78,9 @@ static QemuOptsList qemu_virtfs_opts =3D { > >=20 > > .name =3D "readonly", > > .type =3D QEMU_OPT_BOOL, > > =20 > > }, { > >=20 > > + .name =3D "multidevs", > > + .type =3D QEMU_OPT_STRING, > > + }, { > >=20 > > .name =3D "socket", > > .type =3D QEMU_OPT_STRING, > > =20 > > }, { > >=20 > > diff --git a/fsdev/qemu-fsdev.c b/fsdev/qemu-fsdev.c > > index 077a8c4e2b..ed03d559a9 100644 > > --- a/fsdev/qemu-fsdev.c > > +++ b/fsdev/qemu-fsdev.c > > @@ -58,6 +58,7 @@ static FsDriverTable FsDrivers[] =3D { > >=20 > > "writeout", > > "fmode", > > "dmode", > >=20 > > + "multidevs", >=20 > So we only allow this for the "local" backend. Any reason not to > add this to "proxy" as well ? >=20 > I didn't do it for the "throttling" options because it is a > feature I didn't care to support much, but "multidevs" is more > a fix than a fancy feature. Well, to be honest I haven't cared about the proxy backend at all. Like I=20 mentioned before, I am a bit sceptical that the proxy feature is actually u= sed=20 by people in real life at all (at least in its current implementation). So= =20 personally I don't see much sense in investing time for adding & testing ne= w=20 things on this backend ATM. > > + if (multidevs) { > > + if (!strcmp(multidevs, "remap")) { > > + fsle->fse.export_flags &=3D ~V9FS_FORBID_MULTIDEVS; > > + fsle->fse.export_flags |=3D V9FS_REMAP_INODES; > > + } else if (!strcmp(multidevs, "forbid")) { > > + fsle->fse.export_flags &=3D ~V9FS_REMAP_INODES; > > + fsle->fse.export_flags |=3D V9FS_FORBID_MULTIDEVS; > > + } >=20 > And... >=20 > } else if (!strcmp(multidevs, "warn")) { > fsle->fse.export_flags &=3D ~V9FS_FORBID_MULTIDEVS; > fsle->fse.export_flags &=3D ~V9FS_REMAP_INODES; > } else { > error_setg(errp, "invalid multidevs property '%s'", multidevs= ); > return -1; > } >=20 > ... because we're a bit pedantic for command line options :) And I thought I adapted to relaxed handling of CLI arguments. See existing= =20 option "writeout". :) >=20 > > + } > >=20 > > if (fsle->fse.ops->parse_opts) { > > =20 > > if (fsle->fse.ops->parse_opts(opts, &fsle->fse, errp)) { > >=20 > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > > index 8cc65c2c67..c96ea51116 100644 > > --- a/hw/9pfs/9p.c > > +++ b/hw/9pfs/9p.c > > @@ -25,6 +25,7 @@ > >=20 > > #include "trace.h" > > #include "migration/blocker.h" > > #include "sysemu/qtest.h" > >=20 > > +#include "qemu/xxhash.h" > >=20 > > int open_fd_hw; > > int total_open_fd; > >=20 > > @@ -571,22 +572,109 @@ static void coroutine_fn virtfs_reset(V9fsPDU *p= du) > >=20 > > P9_STAT_MODE_NAMED_PIPE | \ > > P9_STAT_MODE_SOCKET) > >=20 > > -/* This is the algorithm from ufs in spfs */ > > + > > +/* creative abuse of tb_hash_func7, which is based on xxhash */ > > +static uint32_t qpp_hash(QppEntry e) > > +{ > > + return qemu_xxhash7(e.ino_prefix, e.dev, 0, 0, 0); > > +} > > + > > +static bool qpp_lookup_func(const void *obj, const void *userp) > > +{ > > + const QppEntry *e1 =3D obj, *e2 =3D userp; > > + return e1->dev =3D=3D e2->dev && e1->ino_prefix =3D=3D e2->ino_pre= fix; > > +} > > + > > +static void qpp_table_remove(void *p, uint32_t h, void *up) > > +{ > > + g_free(p); > > +} > > + > > +static void qpp_table_destroy(struct qht *ht) > > +{ > > + qht_iter(ht, qpp_table_remove, NULL); > > + qht_destroy(ht); > > +} >=20 > Ok to have a function for this instead of open-coding but I'd > like to see qpp_table_init() for consistency. Well, these are just qht_init() one-liners, but if you really want to have= =20 dedicated, local init functions for them, okay. > > static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID > > *qidp) { > >=20 > > + int err; > >=20 > > size_t size; > >=20 > > - if (pdu->s->dev_id !=3D stbuf->st_dev) { > > - error_report_once( > > - "9p: Multiple devices detected in same VirtFS export. " > > - "You must use a separate export for each device." > > - ); > > - return -ENODEV; > > + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { > > + /* map inode+device to qid path (fast path) */ > > + err =3D qid_path_prefixmap(pdu, stbuf, &qidp->path); > > + if (err) { > > + return err; > > + } > > + } else { > > + if (pdu->s->dev_id !=3D stbuf->st_dev) { > > + if (pdu->s->ctx.export_flags & V9FS_FORBID_MULTIDEVS) { > > + error_report_once( > > + "9p: Multiple devices detected in same VirtFS expo= rt. > > " + "Access of guest to additional devices is (partl= y) > > " + "denied due to virtfs option 'multidevs=3Dforbid' > > being " + "effective." > > + ); > > + return -ENODEV; > > + } else { > > + error_report_once( >=20 > Please use warn_report_once(). Sure! > > + "9p: Multiple devices detected in same VirtFS expo= rt, > > " + "which might lead to file ID collisions and seve= re > > " + "misbehaviours on guest! You should either use a= " > > + "separate export for each device shared from host = or > > " + "use virtfs option 'multidevs=3Dremap'!" > > + ); > > + } > > + } > > + memset(&qidp->path, 0, sizeof(qidp->path)); > > + size =3D MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); > > + memcpy(&qidp->path, &stbuf->st_ino, size); > >=20 > > } > >=20 > > - memset(&qidp->path, 0, sizeof(qidp->path)); > > - size =3D MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); > > - memcpy(&qidp->path, &stbuf->st_ino, size); > >=20 > > qidp->version =3D stbuf->st_mtime ^ (stbuf->st_size << 8); > > qidp->type =3D 0; > > if (S_ISDIR(stbuf->st_mode)) { > >=20 > > @@ -616,6 +704,30 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, > > V9fsFidState *fidp,>=20 > > return 0; > > =20 > > } > >=20 > > +static int coroutine_fn dirent_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, > > + struct dirent *dent, V9fsQID *qi= dp) > > +{ > > + struct stat stbuf; > > + V9fsPath path; > > + int err; > > + > > + v9fs_path_init(&path); > > + > > + err =3D v9fs_co_name_to_path(pdu, &fidp->path, dent->d_name, &path= ); > > + if (err < 0) { > > + goto out; > > + } > > + err =3D v9fs_co_lstat(pdu, &path, &stbuf); > > + if (err < 0) { > > + goto out; > > + } > > + err =3D stat_to_qid(pdu, &stbuf, qidp); > > + > > +out: > > + v9fs_path_free(&path); > > + return err; > > +} > > + > >=20 > > V9fsPDU *pdu_alloc(V9fsState *s) > > { > > =20 > > V9fsPDU *pdu =3D NULL; > >=20 > > @@ -1964,16 +2076,39 @@ static int coroutine_fn v9fs_do_readdir(V9fsPDU > > *pdu, V9fsFidState *fidp,>=20 > > v9fs_string_free(&name); > > return count; > > =20 > > } > >=20 > > - /* > > - * Fill up just the path field of qid because the client uses > > - * only that. To fill the entire qid structure we will have > > - * to stat each dirent found, which is expensive > > - */ > > - size =3D MIN(sizeof(dent->d_ino), sizeof(qid.path)); > > - memcpy(&qid.path, &dent->d_ino, size); > > - /* Fill the other fields with dummy values */ > > - qid.type =3D 0; > > - qid.version =3D 0; > > + > > + if (pdu->s->ctx.export_flags & V9FS_REMAP_INODES) { > > + /* > > + * dirent_to_qid() implies expensive stat call for each > > entry, > > + * we must do that here though since inode remapping requi= res > > + * the device id, which in turn might be different for > > + * different entries; we cannot make any assumption to avo= id > > + * that here. > > + */ > > + err =3D dirent_to_qid(pdu, fidp, dent, &qid); > > + if (err < 0) { > > + v9fs_readdir_unlock(&fidp->fs.dir); > > + v9fs_co_seekdir(pdu, fidp, saved_dir_pos); > > + v9fs_string_free(&name); > > + return err; > > + } > > + } else { > > + /* > > + * Fill up just the path field of qid because the client u= ses > > + * only that. To fill the entire qid structure we will have > > + * to stat each dirent found, which is expensive. For the > > + * latter reason we don't call dirent_to_qid() here. Only > > drawback + * is that no multi-device export detection of > > stat_to_qid() + * would be done and provided as error to the > > user here. But + * user would get that error anyway when > > accessing those + * files/dirs through other ways. > > + */ > > + size =3D MIN(sizeof(dent->d_ino), sizeof(qid.path)); > > + memcpy(&qid.path, &dent->d_ino, size); > > + /* Fill the other fields with dummy values */ > > + qid.type =3D 0; > > + qid.version =3D 0; > > + } > >=20 > > /* 11 =3D 7 + 4 (7 =3D start offset, 4 =3D space for storing c= ount) */ > > len =3D pdu_marshal(pdu, 11 + count, "Qqbs", > >=20 > > @@ -3672,8 +3807,13 @@ int v9fs_device_realize_common(V9fsState *s, con= st > > V9fsTransport *t,>=20 > > goto out; > > =20 > > } > >=20 > > + s->root_ino =3D stat.st_ino; > >=20 > > s->dev_id =3D stat.st_dev; > >=20 > > + /* QID path hash table. 1 entry ought to be enough for anybody ;) = */ > > + qht_init(&s->qpp_table, qpp_lookup_func, 1, QHT_MODE_AUTO_RESIZE); > > + s->qp_prefix_next =3D 1; /* reserve 0 to detect overflow */ > > + > >=20 > > s->ctx.fst =3D &fse->fst; > > fsdev_throttle_init(s->ctx.fst); > >=20 > > @@ -3687,6 +3827,7 @@ out: > > } > > g_free(s->tag); > > g_free(s->ctx.fs_root); > >=20 > > + qpp_table_destroy(&s->qpp_table); >=20 > This causes QEMU to crash if we get there before qht_init() was called. > This should be guarded by a s->qpp_table.map !=3D NULL check. Touch=E9. I'll add that to qp_table_destroy() for simplicity. > I've just posted a patch that simplifies error handling in this > function, you in Cc. The patch is also in 9p-next. Please rebase > on top of it. Ok. =20 > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 9621e934c0..603e5e8e15 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -1335,17 +1335,17 @@ ETEXI > >=20 > > DEF("virtfs", HAS_ARG, QEMU_OPTION_virtfs, > > =20 > > "-virtfs > > local,path=3Dpath,mount_tag=3Dtag,security_model=3Dmapped-xattr|ma= pped-fil > > e|passthrough|none\n">=20 > > - " =20 > > [,id=3Did][,writeout=3Dimmediate][,readonly][,fmode=3Dfmode][,dmode=3Dd= mode]\n" - > > "-virtfs > > proxy,mount_tag=3Dtag,socket=3Dsocket[,id=3Did][,writeout=3Dimmediate][= ,readonly] > > \n" - "-virtfs > > proxy,mount_tag=3Dtag,sock_fd=3Dsock_fd[,id=3Did][,writeout=3Dimmediate= ][,readonl > > y]\n" + " =20 > > [,id=3Did][,writeout=3Dimmediate][,readonly][,fmode=3Dfmode][,dmode=3Dd= mode][,mul > > tidevs=3Dremap|forbid|warn]\n" + "-virtfs > > proxy,mount_tag=3Dtag,socket=3Dsocket[,id=3Did][,writeout=3Dimmediate][= ,readonly] > > [,multidevs=3Dremap|forbid|warn]\n" + "-virtfs > > proxy,mount_tag=3Dtag,sock_fd=3Dsock_fd[,id=3Did][,writeout=3Dimmediate= ][,readonl > > y][,multidevs=3Dremap|forbid|warn]\n" > Either enable support in "proxy" or don't update the "proxy" documentation > :) Then, if you don't mind, I'll just drop it from the proxy documentation, fo= r=20 the reasons I described above. > > "-virtfs synth,mount_tag=3Dtag[,id=3Did][,readonly]\n", > > QEMU_ARCH_ALL) > > =20 > > STEXI > >=20 > > -@item -virtfs local,path=3D@var{path},mount_tag=3D@var{mount_tag} > > ,security_model=3D@var{security_model}[,writeout=3D@var{writeout}][,rea= donly] > > [,fmode=3D@var{fmode}][,dmode=3D@var{dmode}] -@itemx -virtfs > > proxy,socket=3D@var{socket},mount_tag=3D@var{mount_tag} > > [,writeout=3D@var{writeout}][,readonly] -@itemx -virtfs > > proxy,sock_fd=3D@var{sock_fd},mount_tag=3D@var{mount_tag} > > [,writeout=3D@var{writeout}][,readonly] +@item -virtfs > > local,path=3D@var{path},mount_tag=3D@var{mount_tag} > > ,security_model=3D@var{security_model}[,writeout=3D@var{writeout}][,rea= donly] > > [,fmode=3D@var{fmode}][,dmode=3D@var{dmode}][,multidevs=3D@var{multidev= s}] > > +@itemx -virtfs proxy,socket=3D@var{socket},mount_tag=3D@var{mount_tag} > > [,writeout=3D@var{writeout}][,readonly][,multidevs=3D@var{multidevs}] += @itemx > > -virtfs proxy,sock_fd=3D@var{sock_fd},mount_tag=3D@var{mount_tag} > > [,writeout=3D@var{writeout}][,readonly][,multidevs=3D@var{multidevs}] > Ditto. Ack. > > @itemx -virtfs synth,mount_tag=3D@var{mount_tag} > > @findex -virtfs > >=20 > > @@ -1399,6 +1399,27 @@ Specifies the default mode for newly created > > directories on the host. Works>=20 > > only with security models "mapped-xattr" and "mapped-file". > > @item mount_tag=3D@var{mount_tag} > > Specifies the tag name to be used by the guest to mount this export > > point. > >=20 > > +@item multidevs=3D@var{multidevs} > > +Specifies how to deal with multiple devices being shared with a 9p > > export. > > +Supported behaviours are either "remap", "forbid" or "warn". The latter > > is > > +the default behaviour on which virtfs 9p expects only one device to be > > +shared with the same export, and if more than one device is shared and > > +accessed via the same 9p export then only a warning message is logged > > +(once) by qemu on host side. In order to avoid file ID collisions on > > guest > > +you should either create a separate virtfs export for each device to be > > +shared with guests (recommended way) or you might use "remap" instead > > which +allows you to share multiple devices with only one export instea= d, > > which is +achieved by remapping the original inode numbers from host to > > guest in a +way that would prevent such collisions. Remapping inodes in > > such use cases +is required because the original device IDs from host a= re > > never passed and +exposed on guest. Instead all files of an export shar= ed > > with virtfs always +share the same device id on guest. So two files with > > identical inode +numbers but from actually different devices on host > > would otherwise cause a +file ID collision and hence potential > > misbehaviours on guest. "forbid" on +the other hand assumes like "warn" > > that only one device is shared by the +same export, however it will not > > only log a warning message but also +deny access to additional devices = on > > guest. Note though that "forbid" does +currently not block all possible > > file access operations. >=20 > Maybe provide a list of such operations that won't be blocked ? I feel punished for being so verbose. Okaaay. :) >=20 > > @end table > > ETEXI > >=20 > > diff --git a/vl.c b/vl.c > > index b426b32134..9cb29b483d 100644 > > --- a/vl.c > > +++ b/vl.c > > @@ -3320,7 +3320,7 @@ int main(int argc, char **argv, char **envp) > >=20 > > case QEMU_OPTION_virtfs: { > > =20 > > QemuOpts *fsdev; > > QemuOpts *device; > >=20 > > - const char *writeout, *sock_fd, *socket, *path, > > *security_model; + const char *writeout, *sock_fd, > > *socket, *path, *security_model, *multidevs;>=20 > > olist =3D qemu_find_opts("virtfs"); > > if (!olist) { > >=20 > > @@ -3380,6 +3380,10 @@ int main(int argc, char **argv, char **envp) > >=20 > > qemu_opt_set_bool(fsdev, "readonly", > > =20 > > qemu_opt_get_bool(opts, "readonly", = 0), > > &error_abort); > >=20 > > + multidevs =3D qemu_opt_get(opts, "multidevs"); > > + if (multidevs) { > > + qemu_opt_set(fsdev, "multidevs", multidevs, > > &error_abort); + } > >=20 > > device =3D qemu_opts_create(qemu_find_opts("device"), = NULL, > > 0, > > =20 > > &error_abort); > > =20 > > qemu_opt_set(device, "driver", "virtio-9p-pci", > > &error_abort);