From nobody Fri Nov 14 19:46:55 2025 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; 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=fail(p=reject dis=none) header.from=rsg.ci.i.u-tokyo.ac.jp Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1761718453412356.77596805222583; Tue, 28 Oct 2025 23:14:13 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vDzR9-0000eE-ME; Wed, 29 Oct 2025 02:13:35 -0400 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 1vDzQz-0000Yw-Nw for qemu-devel@nongnu.org; Wed, 29 Oct 2025 02:13:26 -0400 Received: from www3579.sakura.ne.jp ([49.212.243.89]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vDzQr-0006q7-0J for qemu-devel@nongnu.org; Wed, 29 Oct 2025 02:13:24 -0400 Received: from h205.csg.ci.i.u-tokyo.ac.jp (h205.csg.ci.i.u-tokyo.ac.jp [133.11.54.205]) (authenticated bits=0) by www3579.sakura.ne.jp (8.16.1/8.16.1) with ESMTPSA id 59T6CsDU077258 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Wed, 29 Oct 2025 15:13:03 +0900 (JST) (envelope-from odaki@rsg.ci.i.u-tokyo.ac.jp) DKIM-Signature: a=rsa-sha256; bh=tIt956zL/G9YcAqkI1Zxo7iDKVwcFbMfxHwZMsjOBfY=; c=relaxed/relaxed; d=rsg.ci.i.u-tokyo.ac.jp; h=From:Date:Subject:Message-Id:To; s=rs20250326; t=1761718383; v=1; b=wXdzSBFwJZ9k/fvodBj2R16u5W/FqFDAcOeVdJ8g5TxVrSGI9rvyFdtrez2kuPHL 2osp27TuHkpoEBTnZlEIoMlNbhhRlJMLt43/t7TSgZv+z+k4f5Xnnr8mmZhe3JJT 1JBRYevZYd/iio6aObtJOwe0fNpx943iMlWitJvTecpKNRzNINzRi0krRqL8/EUL VQAHXttCZWCQjXB0J7fUrwLjWIUywTTqQnhaQJN4Gw5GMkIooo+l5O2cNOkvQ8hQ /CmQmTe0ioAad0EqgQZGXPMvr1+8rtxPq84JZfTpYL/J3zblRinbkrV4v6rw1s+C aqyK7kVa4RiWIqeoDrSy+w== From: Akihiko Odaki Date: Wed, 29 Oct 2025 15:12:49 +0900 Subject: [PATCH 5/5] virtio-gpu: Force RCU when unmapping blob MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251029-force_rcu-v1-5-bf860a6277a6@rsg.ci.i.u-tokyo.ac.jp> References: <20251029-force_rcu-v1-0-bf860a6277a6@rsg.ci.i.u-tokyo.ac.jp> In-Reply-To: <20251029-force_rcu-v1-0-bf860a6277a6@rsg.ci.i.u-tokyo.ac.jp> To: qemu-devel@nongnu.org, Dmitry Osipenko Cc: Paolo Bonzini , "Michael S. Tsirkin" , =?utf-8?q?Alex_Benn=C3=A9e?= , Akihiko Odaki X-Mailer: b4 0.15-dev-179e8 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=49.212.243.89; envelope-from=odaki@rsg.ci.i.u-tokyo.ac.jp; helo=www3579.sakura.ne.jp X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1761718455449154100 Unmapping a blob changes the memory map, which is protected with RCU. RCU is designed to minimize the read-side overhead at the cost of reclamation delay. While this design usually makes sense, it is problematic when unmapping a blob because the operation blocks all virtio-gpu commands and causes perceivable disruption. Minimize such the disruption with force_rcu(), which minimizes the reclamation delay at the cost of a read-side overhead. Signed-off-by: Akihiko Odaki Tested-by: Dmitry Osipenko --- hw/display/virtio-gpu-virgl.c | 1 + 1 file changed, 1 insertion(+) diff --git a/hw/display/virtio-gpu-virgl.c b/hw/display/virtio-gpu-virgl.c index 07f6355ad62e..71cde671c193 100644 --- a/hw/display/virtio-gpu-virgl.c +++ b/hw/display/virtio-gpu-virgl.c @@ -187,6 +187,7 @@ virtio_gpu_virgl_unmap_resource_blob(VirtIOGPU *g, memory_region_set_enabled(mr, false); memory_region_del_subregion(&b->hostmem, mr); object_unparent(OBJECT(mr)); + force_rcu(); } =20 return 0; --=20 2.51.0