From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pz2-f12.google.com (mail-pz2-f12.google.com [74.125.228.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id ABE512C0F6D for ; Sat, 19 Sep 2026 13:18:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.228.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789823892; cv=none; b=Yp5CEvAfaeDwieIEiG2fWkwYlEKSvzy+UiNy4YbdRa0HyXv5AcytalSheQAuFloP8D92gjjC3w7r0z3GBf93n51RCAEKNzv5HApPOij/wiXMkg1aKvk4j6T+hoG39X4bScwCOYmOLHMoILi27kZzlgAdjGQhu+LN5XC6Mua9njo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789823892; c=relaxed/simple; bh=CsmY2C0LUhQFV2xkI5Vula3YY7rYEiZTWt4OODXOZMg=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=ZvbyCtfF+YagurAk0cqPEmEPD3D2K+h6q2MN+sTe/i5s9cwf3hlTvJDgVx+kTOXMMMbL40ctT0qJ32i7dmKZN0JU8FRY+TcLB0WV35Gq8XAU/zvv8gcF8d9G/LiqhgJM9bY6nxMp0H1bFo3+t5ZJi80/dD38VPmiZAj3W11koTw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=I5T4SkdM; arc=none smtp.client-ip=74.125.228.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="I5T4SkdM" Received: by mail-pz2-f12.google.com with SMTP id 41be03b00d2f7-cc1cea4c7a0so849935a12.1 for ; Sat, 19 Sep 2026 06:18:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1789823889; x=1790428689; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to:content-type; bh=JsTGylBrKeTBmgAOYV6+2j7T7Vnx2su+clGWmC3zkts=; b=I5T4SkdMoeg+bxeMvG5McZrykI2Poa08KbsvifYwWq+TYVoL9fB/y/qsEEORnF5QmA MjgaaxhJMT9bRZb3eIXVpRLSFHV1DPZw7LRKEdsfCtlLdvy4fFlMCzESs8v9Lm9Qjyhm SPi1thXSJ0vYYg1d/L0fhUzzo10gtT4OAKgylP6uIxWI50yk2RnIAQI6Sb0onhsOOtyY X3d2pFU4TZGnOzm2PKycIUKKxYJSb9H8biM+PSKdyGioE23LV0o4sR7cqvjRIaW1Z17n fItzu3tjyVDmezvW4HcnMoVaquIgjRc/NBLre01b1arThe+BwbsTKylZnnUyPYrw0i8p HNfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789823889; x=1790428689; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=JsTGylBrKeTBmgAOYV6+2j7T7Vnx2su+clGWmC3zkts=; b=RuqVbr7Y8HmkPXElAcFvVZrV8NKSlQKRXNGBUZ5dFeBWKaeRHXbyKHNAh8PdZPswbv edb2J8TT1hiV+B7J+lnyUVFGrY2FHswOfPu13se/c59WBbnsNH4iY54kkCCTj/uxhAwS /cueTcVVnZKffjofxI+SsrzMo9sYYN36SObccQxdy5p1sJoSNSxyD5lp74H8QAI2VAnR s6sT4hBufRapBx/ophsUV5MGvQhcxLrKrGIFiTZjf8qZVDFjl01P7P8Uf3WlzASrZQWB coxnK3rrfzdVwfwZjZRCoNFwIkldnpSzJyFTAeDC7HIb/jO80GLnkVV+MqdBbh2YxNzb NNsw== X-Forwarded-Encrypted: i=1; AKwUvBw8jaasYuUmobfT24P9PsV936WcB1nXRso5452dqA/V9bUerKuzV562KczQDZ6S7UXcssTZvTM=@vger.kernel.org X-Gm-Message-State: AFuF++kD/aLLln87rrWCQ8Zu6FDxR5jCP7tLEYZRh6yEtp/5fO+/4V4h v4aA6QtpQH3WmGZ/DpagUtVrVTN82gCC5iQLR7ip91ZgXk+MkQiGuNhY X-Gm-Gg: AYBFou3+lBeOXtW6r51ckO3PlVibnOovF4XJ8USywXH3/i/IK/WSae1agn8ky5CAkZD 12H3XUFRChLFqewtESFwfbSyLicJsSNP9pXOYni0OJON2pCUaSw0h2JCGEr3b52gQ+i3G5OjnOF 74z0Xhymru0e579B9/HbKG4cntKUZ4AQwxmXExTwiIoWNkCU5jzxzFZF78w7rCSNghJHKGBYzB4 jFqMpx3LxUlwHi+THuA8ujkgFSpjmB0gTmmDijAecQq9bWM0jzRgQ1uArC3UeBaFjNOE2JLX2fL aHvgbBtP5k6t852KFNpetzdy4X6EK0RtXK8p/qyTq/yTef7Jfdtkf0Gt2Ut8iJEKhleyXI4CkNm O9PHcEe3FLvHqn75eLUIfS+BDCvAWS80b2Dux4WHg8XPKeoI5lHL79yNJnMChiwR6Q8wUjnJDos hXLZHYEiqMbIQQba/gheggreY8kSahPEAehsQP/y6+0G0lKTcLM7Q3jga/wejgNxD8kCQVsg== X-Received: by 2002:a17:90b:5706:b0:39e:6c6a:209e with SMTP id 98e67ed59e1d1-39e6c6a234emr3242069a91.63.1789823888812; Sat, 19 Sep 2026 06:18:08 -0700 (PDT) Received: from gmail.com ([188.253.12.32]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a023cf10bbsm1276314a91.3.2026.09.19.06.18.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 19 Sep 2026 06:18:08 -0700 (PDT) From: Jia Jia To: "Michael S . Tsirkin" Cc: Jason Wang , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , Nicholas Bellinger , kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] vhost: keep vring addresses stable while the backend is attached Date: Sat, 19 Sep 2026 21:17:44 +0800 Message-Id: <20260919131744.131030-1-physicalmtea@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit vhost-scsi keeps the response and bounce-buffer iovecs until the backend completes the command. If userspace changes the vring addresses while the command is in flight, the completion data is copied through the old iovecs while vhost_add_used() updates the new used ring. The guest then no longer sees the completion. Reject changes to the vring addresses while a backend is attached to the queue. Keep accepting the current addresses so userspace can update VHOST_VRING_F_LOG or log_guest_addr without stopping the backend. Queues that have not been attached retain the existing setup behavior; userspace must detach the backend before changing their addresses. Fixes: 057cbf49a1f0 ("tcm_vhost: Initial merge for vhost level target fabric driver") Signed-off-by: Jia Jia --- drivers/vhost/vhost.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 44cac11b68d2..074590838de5 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2150,6 +2150,17 @@ static long vhost_vring_set_addr(struct vhost_dev *d, a.flags & (0x1 << VHOST_VRING_F_LOG), a.log_guest_addr)) return -EINVAL; + + /* + * Commands may retain iovecs derived from the current ring + * addresses. Keep the addresses unchanged while the backend + * is attached. + */ + if ((vq->desc || vq->avail || vq->used) && + (vq->desc != (void __user *)(unsigned long)a.desc_user_addr || + vq->avail != (void __user *)(unsigned long)a.avail_user_addr || + vq->used != (void __user *)(unsigned long)a.used_user_addr)) + return -EBUSY; } vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG));