From patchwork Mon Feb 19 17:31:51 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jonathan Cameron X-Patchwork-Id: 13562936 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 CBBBAC48BC3 for ; Mon, 19 Feb 2024 17:32:45 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rc7VG-0003Zs-8q; Mon, 19 Feb 2024 12:32:30 -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 1rc7VF-0003Zd-1j for qemu-devel@nongnu.org; Mon, 19 Feb 2024 12:32:29 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rc7VC-0004JR-BL for qemu-devel@nongnu.org; Mon, 19 Feb 2024 12:32:28 -0500 Received: from mail.maildlp.com (unknown [172.18.186.31]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4TdqJB05nKz6K6Dq; Tue, 20 Feb 2024 01:28:26 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 12E0A140516; Tue, 20 Feb 2024 01:32:23 +0800 (CST) Received: from SecurePC-101-06.china.huawei.com (10.122.247.231) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Mon, 19 Feb 2024 17:32:22 +0000 To: , Peter Maydell , Gregory Price , =?utf-8?q?Alex_Benn=C3=A9e?= , Sajjan Rao , Dimitrios Palyvos , , Paolo Bonzini , Eduardo Habkost , =?utf-8?q?Philippe_Mathieu-Daud?= =?utf-8?q?=C3=A9?= CC: , Subject: [PATCH v2 1/3] accel/tcg: Set can_do_io at at start of lookup_tb_ptr helper Date: Mon, 19 Feb 2024 17:31:51 +0000 Message-ID: <20240219173153.12114-2-Jonathan.Cameron@huawei.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240219173153.12114-1-Jonathan.Cameron@huawei.com> References: <20240219173153.12114-1-Jonathan.Cameron@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.122.247.231] X-ClientProxiedBy: lhrpeml100006.china.huawei.com (7.191.160.224) To lhrpeml500005.china.huawei.com (7.191.163.240) Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Reply-to: Jonathan Cameron X-Patchwork-Original-From: Jonathan Cameron via From: Jonathan Cameron Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Peter Maydell If a page table is in IO memory and lookup_tb_ptr probes the TLB it can result in a page table walk for the instruction fetch. If this hits IO memory and io_prepare falsely assumes it needs to do a TLB recompile. Avoid that by setting can_do_io at the start of lookup_tb_ptr. Link: https://lore.kernel.org/qemu-devel/CAFEAcA_a_AyQ=Epz3_+CheAT8Crsk9mOu894wbNW_FywamkZiw@mail.gmail.com/#t Reviewed-by: Richard Henderson Signed-off-by: Peter Maydell Signed-off-by: Jonathan Cameron --- v2: Picked up tags and adjusted patch description as question now resolved (whether Peter was happy to give SoB) accel/tcg/cpu-exec.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c index 977576ca14..52239a441f 100644 --- a/accel/tcg/cpu-exec.c +++ b/accel/tcg/cpu-exec.c @@ -396,6 +396,14 @@ const void *HELPER(lookup_tb_ptr)(CPUArchState *env) uint64_t cs_base; uint32_t flags, cflags; + /* + * By definition we've just finished a TB, so I/O is OK. + * Avoid the possibility of calling cpu_io_recompile() if + * a page table walk triggered by tb_lookup() calling + * probe_access_internal() happens to touch an MMIO device. + * The next TB, if we chain to it, will clear the flag again. + */ + cpu->neg.can_do_io = true; cpu_get_tb_cpu_state(env, &pc, &cs_base, &flags); cflags = curr_cflags(cpu);