From patchwork Thu Mar 9 08:51:01 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Viresh Kumar X-Patchwork-Id: 13167007 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id F1E6BC64EC4 for ; Thu, 9 Mar 2023 08:52:08 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1paBzZ-0007qk-0K; Thu, 09 Mar 2023 03:51:17 -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 1paBzY-0007qV-18 for qemu-devel@nongnu.org; Thu, 09 Mar 2023 03:51:16 -0500 Received: from mail-pl1-x635.google.com ([2607:f8b0:4864:20::635]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.90_1) (envelope-from ) id 1paBzW-00026u-Cq for qemu-devel@nongnu.org; Thu, 09 Mar 2023 03:51:15 -0500 Received: by mail-pl1-x635.google.com with SMTP id u5so1249950plq.7 for ; Thu, 09 Mar 2023 00:51:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1678351873; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=ETLRpO4UaRJv+Jq2cQ1jDXzLWWERHBPOjdPoPBs2HQY=; b=kaY7yb4BgtrBRVTJaGL5YIn9l8IoTa4lyVgMiGE+LSI7rvLuSg3awOMLMnJLOKt+lH W6d6qR1BZdYIAWI86ipKF6SAvHJt12FDfZXzQex6uuHUqOU7GSMF4kJO+V+fxbDxpS9X 1dJ3CqLWQIk1MgmIX8taEexVVxGkBm/1PAv3hF+VF4Dlx80Hf3qHflMdy/POb2dqLAQn i69WPePj9IV5csX+pp+JjQj9I7BQIWVsygdYSUfiVRefrtYWhnYRgXKGdJIOd+6SyfKz C27SGThUJCnUOCTvUfZydDQw+hvdAW4FM7Ke9ONCK8itnaWY98VCIDjqH3mAa3AaK+0A 026g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1678351873; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=ETLRpO4UaRJv+Jq2cQ1jDXzLWWERHBPOjdPoPBs2HQY=; b=O0nW07SuWnXlSiRd4aIbbx+ZJEIbFKTtlbZmLkwoWbSVFlKt6qm6W1z0c+KBcvfaOH F+szb962L3gN9RmS09SS5FDXaE4VN2kikLLKVNRKCAmhw34HOhQKKT1UMHMNFIJBO6uF C/kVI6eR3WANAeK/lhBNoP9h1HZHL/yKbb/WsE4g9BtIEFCV5zThJTOgJLzoWN723HP7 7cg1du9mZPNOYCJsA3GE/QErqMMTFmCIbQtEiTOYJ0M8/9G1RSXJ8ZqnWTrxYtoDevVy 3pReDgZysMm9/VFRV1Va5ZANxmQ9Mc1JWmWcC+sbGL5ytulO/DTStx+/VsFqPQJ/dR1P PbDA== X-Gm-Message-State: AO0yUKUYhJFYpNK9YYbs5WztXyUTgm/Ozk/gO+Hc9h/0X68Pi9Il9f3J mfSfQt4rUZMRdji7ZBhAan4Ek+PewyI+bJEFxgM= X-Google-Smtp-Source: AK7set/6Djb1zMP9YhPTkWppkZDJ0L3CO0duyd+NyeHjm4Zil4YeTAqUaIBzL/6AzT6fjqaHkZW0kA== X-Received: by 2002:a17:902:c14c:b0:19d:74c:78e4 with SMTP id 12-20020a170902c14c00b0019d074c78e4mr18866811plj.55.1678351872801; Thu, 09 Mar 2023 00:51:12 -0800 (PST) Received: from localhost ([122.172.83.155]) by smtp.gmail.com with ESMTPSA id kt16-20020a170903089000b0019a7385079esm11058153plb.123.2023.03.09.00.51.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Mar 2023 00:51:12 -0800 (PST) From: Viresh Kumar To: qemu-devel@nongnu.org, virtio-dev@lists.oasis-open.org, Stefan Hajnoczi , "Michael S. Tsirkin" Cc: Viresh Kumar , Vincent Guittot , =?utf-8?q?Alex_Benn=C3=A9e?= , stratos-dev@op-lists.linaro.org, Oleksandr Tyshchenko , xen-devel@lists.xen.org, Andrew Cooper , Juergen Gross , Sebastien Boeuf , Liu Jiang , Mathieu Poirier Subject: [PATCH V3 2/2] docs: vhost-user: Add Xen specific memory mapping support Date: Thu, 9 Mar 2023 14:21:01 +0530 Message-Id: <6d0bd7f0e1aeec3ddb603ae4ff334c75c7d0d7b3.1678351495.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.31.1.272.g89b43f80a514 In-Reply-To: References: MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::635; envelope-from=viresh.kumar@linaro.org; helo=mail-pl1-x635.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, 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: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org The current model of memory mapping at the back-end works fine where a standard call to mmap() (for the respective file descriptor) is enough before the front-end can start accessing the guest memory. There are other complex cases though where the back-end needs more information and simple mmap() isn't enough. For example Xen, a type-1 hypervisor, currently supports memory mapping via two different methods, foreign-mapping (via /dev/privcmd) and grant-dev (via /dev/gntdev). In both these cases, the back-end needs to call mmap() and ioctl(), with extra information like the Xen domain-id of the guest whose memory we are trying to map. Add a new protocol feature, 'VHOST_USER_PROTOCOL_F_XEN_MMAP', which lets the back-end know about the additional memory mapping requirements. When this feature is negotiated, the front-end will send the additional information within the memory regions themselves. Signed-off-by: Viresh Kumar Reviewed-by: Stefan Hajnoczi Reviewed-by: Alex Bennée --- docs/interop/vhost-user.rst | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst index 1720d681264d..5a070adbc1aa 100644 --- a/docs/interop/vhost-user.rst +++ b/docs/interop/vhost-user.rst @@ -145,6 +145,26 @@ Memory region description :mmap offset: 64-bit offset where region starts in the mapped memory +When the ``VHOST_USER_PROTOCOL_F_XEN_MMAP`` protocol feature has been +successfully negotiated, the memory region description contains two extra +fields at the end. + ++---------------+------+--------------+-------------+----------------+-------+ +| guest address | size | user address | mmap offset | xen mmap flags | domid | ++---------------+------+--------------+-------------+----------------+-------+ + +:xen mmap flags: 32-bit bit field + +- Bit 0 is set for Xen foreign memory mapping. +- Bit 1 is set for Xen grant memory mapping. +- Bit 8 is set if the memory region can not be mapped in advance, and memory + areas within this region must be mapped / unmapped only when required by the + back-end. The back-end shouldn't try to map the entire region at once, as the + front-end may not allow it. The back-end should rather map only the required + amount of memory at once and unmap it after it is used. + +:domid: a 32-bit Xen hypervisor specific domain id. + Single memory region description ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ @@ -864,6 +884,7 @@ Protocol features #define VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS 14 #define VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS 15 #define VHOST_USER_PROTOCOL_F_STATUS 16 + #define VHOST_USER_PROTOCOL_F_XEN_MMAP 17 Front-end message types -----------------------