From nobody Mon Feb 9 03:47:31 2026 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass(p=quarantine dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1770232097; cv=none; d=zohomail.com; s=zohoarc; b=ZcTTd6HEMUtsjb57r2EiRyH+hAlyRrF2uyazcZeNK+0vkZjR4RfbyF4YrCdhL1dS/4Ir6GN3KRaiaKM/Ij1AJzaUvE44AtW1F6tlUuK0cjaOI2EHkD4dlHXaKcJ3faPWTdZ18Dlgb9evJAfZpJv+W1vQ95uJ3xIJw5jVtAz/IQM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1770232097; h=Content-Type:Cc:Cc:Date:Date:From:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:Subject:To:To:Message-Id:Reply-To; bh=1eEfcRbtK2xlCfiX35UT2DVbhf1pwTVIcDLjUARGxQM=; b=YlAXRUP3ombwwZ0afSAUAtvTEj48LQL7dfg+Hieb0w90ajIMLMHbUMDsNoauv2iOy294ydioqNj7lmm7/mPyT/y2AmkmFPSeHmswclyWl0ymi2veQGh3Mv6rE5gCLU9vw+pptss/9L7sy5DIo7mYWtNtLWSJLQL9L2GvWqeUmNE= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 17702320977121007.9632658985163; Wed, 4 Feb 2026 11:08:17 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vniAU-000849-VZ; Wed, 04 Feb 2026 14:04:03 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vniAJ-0007WN-QL for qemu-devel@nongnu.org; Wed, 04 Feb 2026 14:03:52 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vniAH-0007uc-Sm for qemu-devel@nongnu.org; Wed, 04 Feb 2026 14:03:51 -0500 Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-28--qxdtjUqOCKEuWHiyj18fQ-1; Wed, 04 Feb 2026 14:03:47 -0500 Received: by mail-wr1-f72.google.com with SMTP id ffacd0b85a97d-436164e7f42so188258f8f.3 for ; Wed, 04 Feb 2026 11:03:47 -0800 (PST) Received: from redhat.com (IGLD-80-230-34-155.inter.net.il. [80.230.34.155]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-436180659b8sm7888347f8f.43.2026.02.04.11.03.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Feb 2026 11:03:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1770231829; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=1eEfcRbtK2xlCfiX35UT2DVbhf1pwTVIcDLjUARGxQM=; b=YCf/BWIoElUWtMwnmdg9i3xcs3h5dS0riL/SYG/6AQi5i9P1T7tEoliNMYIVhmltiEzLa6 jCyxHiAzy9sxvj47/7nDUFduz0qFcxf/+trb/TpCM8KUJifpw3P2rTin0ifkS3XYQHZduK nVuxmcfxCbqVcm6Yo9P8ks8pwoQ/wso= X-MC-Unique: -qxdtjUqOCKEuWHiyj18fQ-1 X-Mimecast-MFC-AGG-ID: -qxdtjUqOCKEuWHiyj18fQ_1770231827 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1770231826; x=1770836626; darn=nongnu.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=1eEfcRbtK2xlCfiX35UT2DVbhf1pwTVIcDLjUARGxQM=; b=sUio0CruBpA1z13Su8LVckuFGDdyWxtWq+45MnOwD3ykZjua6MLba9g5A9w+IsyWqt JklCMV6XYLHrS0sDIoG6ZL0JzxD5a7vi3zA6XpZ5ziIKAwUzKJKeYYtk3A0fG7QXdUSe +cExfHEHN/mQ2lm5WdgqSeVtvvOG+BChuMFR94BIDreIz2HPfcMFZVzsZXrqkY3R1Huw EfItmcn/nn6toGu3OyMBtoRPGj+XJ27rGhgIRcFp/Tpb+yHCcXYu9o5nM32PShNhndaK lZBjj4P+FMLDzQ4SGb6zP1jW4bUwDIW3+sMn95LmxZ5v0Rlwm8FPy9kUsGw9/YWhRYhp Zk4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770231826; x=1770836626; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=1eEfcRbtK2xlCfiX35UT2DVbhf1pwTVIcDLjUARGxQM=; b=pYY0Uy/1YK40C7xBJQ7YNGIjQ64Je93Y0O1LNtQTSb2z/HmW0hY8rW8Pd1vjd1wcT+ rMWz0P+RS0iXnSHRcW1VMsVhyxbWWOKOZcHXeNc+agLS79WRtf9282GmLUr0KsNrENX2 QPZEQXgbxVgXIq8zVbImOqbHKxgQubgAhrlaiPIG4PJVP+D0QreCIXufp+28GK5qUjpy H+HFUDp6ktth2fThR0taBTIBwrp2RqsqsC6R5ro+eHdsAp7+brjBzu4zUbSKv6DOItcu NBLZcrHkbvEpwYoJqwqEMgnlcS8+Vzi3Fl/zkNDme2OABAjb7uCJ+FYQ0MvR4BM39bmT /g0A== X-Gm-Message-State: AOJu0YzuHED+4yIhWwit5CWZ/H/f50C1o0P8oAFA6xRs0PRNtzY0NsSe iFxC8utUDIkHkv1sfqgn3GlNv6NH2NMtBoEAkRYRttvsi5K7mOU6OeLJ+AFJLxc0jdOrdwHzQcx dn2Q7HMKS7T3fm4i62NTipsbUanR3uAgr6sx1JmZ1Bi0fNJX8Spmr+ZU8Bf0UOZYd5jaq3hK8pK vltQVNroB0kyv/jzB/11Zhu8Y/tHMwRbZzFA== X-Gm-Gg: AZuq6aLjXzNBKrj9h/CbyIQWNK3d59/TfOTdRhdWQ6n+tzDey3ZQQSSDnMGap1f7fab 2/ukWtwwPnh02k5PlbBKraOEkskn6LRAQ88GPFMHPi1ohOGj03xy58Hv3WKFW1YLSi1temSvC0Z +xKhvVJIQvfY3IXlI8bNxxaA6SxLJFXB3uNFyN++O2ogs8D3DSZfcKfQB6oiBOObhfu7x3BbPmH Foro1pOtKHeBnTRrHhbGfoF9hTDJpxrfxYYqHvgO/Y/Xs+16CK+0yEqvVj2SuWFinsBnzutC+nW +eaqb0cxeo2ebF2eb8H8kx0Z4EQ8OvumRlUH+UYVdXaoJB144UgZm8RZzv1HiLPhDL9BUvw2WqM 5NM/pZUQp+5FsADnxUGutJvrpMeTdwL5S2A== X-Received: by 2002:a5d:64e6:0:b0:42f:b707:56dd with SMTP id ffacd0b85a97d-436180551e9mr6170079f8f.33.1770231826191; Wed, 04 Feb 2026 11:03:46 -0800 (PST) X-Received: by 2002:a5d:64e6:0:b0:42f:b707:56dd with SMTP id ffacd0b85a97d-436180551e9mr6170025f8f.33.1770231825628; Wed, 04 Feb 2026 11:03:45 -0800 (PST) Date: Wed, 4 Feb 2026 14:03:43 -0500 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Cc: Peter Maydell , Daniil Tatianin , Stefano Garzarella Subject: [PULL 24/51] virtio/vhost: don't consider non-MAP_SHARED regions public Message-ID: <158f8d3bb06f65cac00bccb681fbd145189a1211.1770231744.git.mst@redhat.com> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1770232098431158500 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Daniil Tatianin Just having a file descriptor is not enough to consider a memory region public. If QEMU didn't map it as MAP_SHARED (in case of share=3Doff), guest writes to this region won't be visible to the vhost-user backend, thus causing it to read all zeroes or garbage. Make sure we don't pass such regions and include that to our definition of what a private region is. Signed-off-by: Daniil Tatianin Fixes: 552b25229c ("vhost: Rework memslot filtering and fix "used_memslot" = tracking") Acked-by: Stefano Garzarella Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Message-Id: <20251113085842.323745-1-d-tatianin@yandex-team.ru> --- hw/virtio/vhost.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 31e9704cdc..c6a5928cb1 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -592,11 +592,13 @@ static bool vhost_section(struct vhost_dev *dev, Memo= ryRegionSection *section) /* * Some backends (like vhost-user) can only handle memory regions * that have an fd (can be mapped into a different process). Filter - * the ones without an fd out, if requested. - * - * TODO: we might have to limit to MAP_SHARED as well. + * the ones without an fd out, if requested. Also make sure that + * this region is mapped as shared so that the vhost backend can + * observe modifications to this region, otherwise we consider it + * private. */ - if (memory_region_get_fd(section->mr) < 0 && + if ((memory_region_get_fd(section->mr) < 0 || + !qemu_ram_is_shared(section->mr->ram_block)) && dev->vhost_ops->vhost_backend_no_private_memslots && dev->vhost_ops->vhost_backend_no_private_memslots(dev)) { trace_vhost_reject_section(mr->name, 2); --=20 MST