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=-15.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 24A2DC47094 for ; Thu, 10 Jun 2021 15:33:15 +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 8DC74613AE for ; Thu, 10 Jun 2021 15:33:14 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8DC74613AE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:43992 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lrMgD-00059w-Oc for qemu-devel@archiver.kernel.org; Thu, 10 Jun 2021 11:33:13 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:54220) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrMd7-0000D1-3j for qemu-devel@nongnu.org; Thu, 10 Jun 2021 11:30:01 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:59335) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lrMd2-0004wP-Po for qemu-devel@nongnu.org; Thu, 10 Jun 2021 11:30:00 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623338995; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6aiSXtYzwvqQDhMuaYAotaWRV4/e4wcz+UBcfKMiIzY=; b=OpQ+j0n1zqcH+tCivek3Q76ppJokkRNueyv87S4/aRdpuYj1bPt7/S6/cAjscpOfox9HG4 cP5yJvfYuwYp/hKYPT6x86833oE7nBYYxXAQ1M45/GXVWUhPaIKYDnN6v94uvcY843Bd1l BQoaauYuToLiiGgVelqqiCjXa64DErA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-215-OgBd3QgKP4ib9ULrv5CFCA-1; Thu, 10 Jun 2021 11:29:54 -0400 X-MC-Unique: OgBd3QgKP4ib9ULrv5CFCA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 2A7F1107ACF6; Thu, 10 Jun 2021 15:29:53 +0000 (UTC) Received: from work-vm (ovpn-114-240.ams2.redhat.com [10.36.114.240]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 60CC059474; Thu, 10 Jun 2021 15:29:44 +0000 (UTC) Date: Thu, 10 Jun 2021 16:29:42 +0100 From: "Dr. David Alan Gilbert" To: Stefan Hajnoczi Subject: Re: [PATCH v3 26/26] virtiofsd: Ask qemu to drop CAP_FSETID if client asked for it Message-ID: References: <20210428110100.27757-1-dgilbert@redhat.com> <20210428110100.27757-27-dgilbert@redhat.com> <20210506160223.GA277745@redhat.com> <20210510152324.GB150402@horse> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.0.7 (2021-05-04) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.199, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=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: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, qemu-devel@nongnu.org, Vivek Goyal , groug@kaod.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Dr. David Alan Gilbert (dgilbert@redhat.com) wrote: > * Stefan Hajnoczi (stefanha@redhat.com) wrote: > > Instead I was thinking about VHOST_USER_DMA_READ/WRITE messages > > containing the address (a device IOVA, it could just be a guest physica= l > > memory address in most cases) and the length. The WRITE message would > > also contain the data that the vhost-user device wishes to write. The > > READ message reply would contain the data that the device read from > > QEMU. > >=20 > > QEMU would implement this using QEMU's address_space_read/write() APIs. > >=20 > > So basically just a new vhost-user protocol message to do a memcpy(), > > but with guest addresses and vIOMMU support :). >=20 > This doesn't actually feel that hard - ignoring vIOMMU for a minute > which I know very little about - I'd have to think where the data > actually flows, probably the slave fd. >=20 > > The vhost-user device will need to do bounce buffering so using these > > new messages is slower than zero-copy I/O to shared guest RAM. >=20 > I guess the theory is it's only in the weird corner cases anyway. The direction I'm going is something like the following; the idea is that the master will have to handle the requests on a separate thread, to avoid any problems with side effects from the memory accesses; the slave will then have to parkt he requests somewhere and handle them later. >From 07aacff77c50c8a2b588b2513f2dfcfb8f5aa9df Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Thu, 10 Jun 2021 15:34:04 +0100 Subject: [PATCH] WIP: vhost-user: DMA type interface A DMA type interface where the slave can ask for a stream of bytes to be read/written to the guests memory by the master. The interface is asynchronous, since a request may have side effects inside the guest. Signed-off-by: Dr. David Alan Gilbert --- docs/interop/vhost-user.rst | 33 +++++++++++++++++++++++ hw/virtio/vhost-user.c | 4 +++ subprojects/libvhost-user/libvhost-user.h | 24 +++++++++++++++++ 3 files changed, 61 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 9ebd05e2bf..b9b5322147 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -1347,6 +1347,15 @@ Master message types query the backend for its device status as defined in the Virtio specification. =20 +``VHOST_USER_MEM_DATA`` + :id: 41 + :equivalent ioctl: N/A + :slave payload: N/A + :master payload: ``struct VhostUserMemReply`` + + This message is an asynchronous response to a ``VHOST_USER_SLAVE_MEM_ACC= ESS`` + message. Where the request was for the master to read data, this + message will be followed by the data that was read. =20 Slave message types ------------------- @@ -1469,6 +1478,30 @@ Slave message types The ``VHOST_USER_FS_FLAG_MAP_W`` flag must be set in the ``flags`` field= to write to the file from RAM. =20 +``VHOST_USER_SLAVE_MEM_ACCESS`` + :id: 9 + :equivalent ioctl: N/A + :slave payload: ``struct VhostUserMemAccess`` + :master payload: N/A + + Requests that the master perform a range of memory accesses on behalf + of the slave that the slave can't perform itself. + + The ``VHOST_USER_MEM_FLAG_TO_MASTER`` flag must be set in the ``flags`` + field for the slave to write data into the RAM of the master. In this + case the data to write follows the ``VhostUserMemAccess`` on the fd. + The ``VHOST_USER_MEM_FLAG_FROM_MASTER`` flag must be set in the ``flags`= ` + field for the slave to read data from the RAM of the master. + + When the master has completed the access it replies on the main fd with + a ``VHOST_USER_MEM_DATA`` message. + + The master is allowed to complete part of the request and reply stating + the amount completed, leaving it to the slave to resend further componen= ts. + This may happen to limit memory allocations in the master or to simplify + the implementation. + + .. _reply_ack: =20 VHOST_USER_PROTOCOL_F_REPLY_ACK diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 39a0e55cca..a3fefc4c1d 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -126,6 +126,9 @@ typedef enum VhostUserRequest { VHOST_USER_GET_MAX_MEM_SLOTS =3D 36, VHOST_USER_ADD_MEM_REG =3D 37, VHOST_USER_REM_MEM_REG =3D 38, + VHOST_USER_SET_STATUS =3D 39, + VHOST_USER_GET_STATUS =3D 40, + VHOST_USER_MEM_DATA =3D 41, VHOST_USER_MAX } VhostUserRequest; =20 @@ -139,6 +142,7 @@ typedef enum VhostUserSlaveRequest { VHOST_USER_SLAVE_FS_MAP =3D 6, VHOST_USER_SLAVE_FS_UNMAP =3D 7, VHOST_USER_SLAVE_FS_IO =3D 8, + VHOST_USER_SLAVE_MEM_ACCESS =3D 9, VHOST_USER_SLAVE_MAX } VhostUserSlaveRequest; =20 diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libvho= st-user/libvhost-user.h index eee611a2f6..b5444f4f6f 100644 --- a/subprojects/libvhost-user/libvhost-user.h +++ b/subprojects/libvhost-user/libvhost-user.h @@ -109,6 +109,9 @@ typedef enum VhostUserRequest { VHOST_USER_GET_MAX_MEM_SLOTS =3D 36, VHOST_USER_ADD_MEM_REG =3D 37, VHOST_USER_REM_MEM_REG =3D 38, + VHOST_USER_SET_STATUS =3D 39, + VHOST_USER_GET_STATUS =3D 40, + VHOST_USER_MEM_DATA =3D 41, VHOST_USER_MAX } VhostUserRequest; =20 @@ -122,6 +125,7 @@ typedef enum VhostUserSlaveRequest { VHOST_USER_SLAVE_FS_MAP =3D 6, VHOST_USER_SLAVE_FS_UNMAP =3D 7, VHOST_USER_SLAVE_FS_IO =3D 8, + VHOST_USER_SLAVE_MEM_ACCESS =3D 9, VHOST_USER_SLAVE_MAX } VhostUserSlaveRequest; =20 @@ -220,6 +224,24 @@ typedef struct VhostUserInflight { uint16_t queue_size; } VhostUserInflight; =20 +/* For the flags field of VhostUserMemAccess and VhostUserMemReply */ +#define VHOST_USER_MEM_FLAG_TO_MASTER (1u << 0) +#define VHOST_USER_MEM_FLAG_FROM_MASTER (1u << 1) +typedef struct VhostUserMemAccess { + uint32_t id; /* Included in the reply */ + uint32_t flags; + uint64_t addr; /* In the bus address of the device */ + uint64_t len; /* In bytes */ +} VhostUserMemAccess; + +typedef struct VhostUserMemReply { + uint32_t id; /* From the request */ + uint32_t flags; + uint32_t err; /* 0 on success */ + uint32_t align; + uint64_t len; +} VhostUserMemReply; + #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__)) # define VU_PACKED __attribute__((gcc_struct, packed)) #else @@ -248,6 +270,8 @@ typedef struct VhostUserMsg { VhostUserVringArea area; VhostUserInflight inflight; VhostUserFSSlaveMsgMax fs_max; + VhostUserMemAccess memaccess; + VhostUserMemReply memreply; } payload; =20 int fds[VHOST_MEMORY_BASELINE_NREGIONS]; --=20 2.31.1 --=20 Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK