From nobody Sun Feb 8 10:41:45 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1518788400896121.29395050858079; Fri, 16 Feb 2018 05:40:00 -0800 (PST) Received: from localhost ([::1]:48600 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emgF1-0003ob-30 for importer@patchew.org; Fri, 16 Feb 2018 08:39:55 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:51958) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1emfsu-0001ej-MA for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:17:07 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1emfst-00067a-Jh for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:17:04 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:40638 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1emfst-00066u-Du for qemu-devel@nongnu.org; Fri, 16 Feb 2018 08:17:03 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 14434EAE91 for ; Fri, 16 Feb 2018 13:17:03 +0000 (UTC) Received: from dgilbert-t530.redhat.com (unknown [10.36.118.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id C0B01213AEE2; Fri, 16 Feb 2018 13:17:01 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, maxime.coquelin@redhat.com, marcandre.lureau@redhat.com, peterx@redhat.com, imammedo@redhat.com, mst@redhat.com Date: Fri, 16 Feb 2018 13:16:19 +0000 Message-Id: <20180216131625.9639-24-dgilbert@redhat.com> In-Reply-To: <20180216131625.9639-1-dgilbert@redhat.com> References: <20180216131625.9639-1-dgilbert@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Fri, 16 Feb 2018 13:17:03 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Fri, 16 Feb 2018 13:17:03 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'dgilbert@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [PATCH v3 23/29] libvhost-user: mprotect & madvises for postcopy X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: aarcange@redhat.com, quintela@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: "Dr. David Alan Gilbert" Clear the area and turn off THP. PROT_NONE the area until after we've userfault advised it to catch any unexpected changes. Signed-off-by: Dr. David Alan Gilbert --- contrib/libvhost-user/libvhost-user.c | 46 +++++++++++++++++++++++++++++++= ---- 1 file changed, 41 insertions(+), 5 deletions(-) diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/= libvhost-user.c index e02e5d6f46..1b224af706 100644 --- a/contrib/libvhost-user/libvhost-user.c +++ b/contrib/libvhost-user/libvhost-user.c @@ -454,7 +454,7 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMsg= *vmsg) int i; VhostUserMemory *memory =3D &vmsg->payload.memory; dev->nregions =3D memory->nregions; - /* TODO: Postcopy specific code */ + DPRINT("Nregions: %d\n", memory->nregions); for (i =3D 0; i < dev->nregions; i++) { void *mmap_addr; @@ -478,9 +478,12 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMs= g *vmsg) =20 /* We don't use offset argument of mmap() since the * mapped address has to be page aligned, and we use huge - * pages. */ + * pages. + * In postcopy we're using PROT_NONE here to catch anyone + * accessing it before we userfault + */ mmap_addr =3D mmap(0, dev_region->size + dev_region->mmap_offset, - PROT_READ | PROT_WRITE, MAP_SHARED, + PROT_NONE, MAP_SHARED, vmsg->fds[i], 0); =20 if (mmap_addr =3D=3D MAP_FAILED) { @@ -519,12 +522,38 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserM= sg *vmsg) /* OK, now we can go and register the memory and generate faults */ for (i =3D 0; i < dev->nregions; i++) { VuDevRegion *dev_region =3D &dev->regions[i]; + int ret; #ifdef UFFDIO_REGISTER /* We should already have an open ufd. Mark each memory * range as ufd. - * Note: Do we need any madvises? Well it's not been accessed - * yet, still probably need no THP to be safe, discard to be safe? + * Discard any mapping we have here; note I can't use MADV_REMOVE + * or fallocate to make the hole since I don't want to lose + * data that's already arrived in the shared process. + * TODO: How to do hugepage */ + ret =3D madvise((void *)dev_region->mmap_addr, + dev_region->size + dev_region->mmap_offset, + MADV_DONTNEED); + if (ret) { + fprintf(stderr, + "%s: Failed to madvise(DONTNEED) region %d: %s\n", + __func__, i, strerror(errno)); + } + /* Turn off transparent hugepages so we dont get lose wakeups + * in neighbouring pages. + * TODO: Turn this backon later. + */ + ret =3D madvise((void *)dev_region->mmap_addr, + dev_region->size + dev_region->mmap_offset, + MADV_NOHUGEPAGE); + if (ret) { + /* Note: This can happen legally on kernels that are configured + * without madvise'able hugepages + */ + fprintf(stderr, + "%s: Failed to madvise(NOHUGEPAGE) region %d: %s\n", + __func__, i, strerror(errno)); + } struct uffdio_register reg_struct; reg_struct.range.start =3D (uintptr_t)dev_region->mmap_addr; reg_struct.range.len =3D dev_region->size + dev_region->mmap_offse= t; @@ -546,6 +575,13 @@ vu_set_mem_table_exec_postcopy(VuDev *dev, VhostUserMs= g *vmsg) } DPRINT("%s: region %d: Registered userfault for %llx + %llx\n", __func__, i, reg_struct.range.start, reg_struct.range.len); + /* Now it's registered we can let the client at it */ + if (mprotect((void *)dev_region->mmap_addr, + dev_region->size + dev_region->mmap_offset, + PROT_READ | PROT_WRITE)) { + vu_panic(dev, "failed to mprotect region %d for postcopy", i); + return false; + } /* TODO: Stash 'zero' support flags somewhere */ #endif } --=20 2.14.3