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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37477C7618A for ; Mon, 20 Mar 2023 15:26:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232806AbjCTP0x (ORCPT ); Mon, 20 Mar 2023 11:26:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36246 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232704AbjCTPYX (ORCPT ); Mon, 20 Mar 2023 11:24:23 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 04B0236447 for ; Mon, 20 Mar 2023 08:17:34 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id D4DB5CE12F1 for ; Mon, 20 Mar 2023 15:17:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC648C433EF; Mon, 20 Mar 2023 15:17:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1679325438; bh=+4SDLqKtYyc36Kv8dUBvjY7sF/JLdSOcZCb+nFhNOxs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LycORzXkte9Y3dX/tdWeUTcwkbDlVzmGnZ6h6iV0mulYLRM+WJ2C8Hs6kZcrWuSnm wrI9l8Qf7ceBJm1tGw+kjXDm+9wrzT8cEj/UmgC+Xklb1caCGUNmq09rVfR6Hpb7fd 9c3cgDGlYUR0ZVyTe6+y8hgiy4IfUP5TDyuWUbXQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Stefano Garzarella , =?UTF-8?q?Eugenio=20P=C3=A9rez?= , "Michael S. Tsirkin" , Sasha Levin Subject: [PATCH 6.2 043/211] vdpa_sim: set last_used_idx as last_avail_idx in vdpasim_queue_ready Date: Mon, 20 Mar 2023 15:52:58 +0100 Message-Id: <20230320145515.039197909@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230320145513.305686421@linuxfoundation.org> References: <20230320145513.305686421@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eugenio Pérez [ Upstream commit b4cca6d48eb3fa6f0d9caba4329b1a2b0ff67a77 ] Starting from an used_idx different than 0 is needed in use cases like virtual machine migration. Not doing so and letting the caller set an avail idx different than 0 causes destination device to try to use old buffers that source driver already recover and are not available anymore. Since vdpa_sim does not support receive inflight descriptors as a destination of a migration, let's set both avail_idx and used_idx the same at vq start. This is how vhost-user works in a VHOST_SET_VRING_BASE call. Although the simple fix is to set last_used_idx at vdpasim_set_vq_state, it would be reset at vdpasim_queue_ready. The last_avail_idx case is fixed with commit 0e84f918fac8 ("vdpa_sim: not reset state in vdpasim_queue_ready"). Since the only option is to make it equal to last_avail_idx, adding the only change needed here. This was discovered and tested live migrating the vdpa_sim_net device. Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator") Reviewed-by: Stefano Garzarella Signed-off-by: Eugenio Pérez Message-Id: <20230302181857.925374-1-eperezma@redhat.com> Signed-off-by: Michael S. Tsirkin Signed-off-by: Sasha Levin --- drivers/vdpa/vdpa_sim/vdpa_sim.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c index 8839232a3fcbc..61bde476cf9c8 100644 --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c @@ -76,6 +76,17 @@ static void vdpasim_queue_ready(struct vdpasim *vdpasim, unsigned int idx) (uintptr_t)vq->device_addr); vq->vring.last_avail_idx = last_avail_idx; + + /* + * Since vdpa_sim does not support receive inflight descriptors as a + * destination of a migration, let's set both avail_idx and used_idx + * the same at vq start. This is how vhost-user works in a + * VHOST_SET_VRING_BASE call. + * + * Although the simple fix is to set last_used_idx at + * vdpasim_set_vq_state, it would be reset at vdpasim_queue_ready. + */ + vq->vring.last_used_idx = last_avail_idx; vq->vring.notify = vdpasim_vq_notify; } -- 2.39.2