From nobody Thu May 15 10:42:17 2025 Delivered-To: importer2@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+importer2=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1699538522830524.7790258821249; Thu, 9 Nov 2023 06:02:02 -0800 (PST) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1r15bG-0008Iv-LD; Thu, 09 Nov 2023 09:01:42 -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 1r15aB-0005nz-Un; Thu, 09 Nov 2023 09:00:34 -0500 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1r15Zz-0005mc-ML; Thu, 09 Nov 2023 09:00:31 -0500 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 04DBA31BC2; Thu, 9 Nov 2023 16:59:42 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id 0EC1A344FB; Thu, 9 Nov 2023 16:59:34 +0300 (MSK) Received: (nullmailer pid 1462791 invoked by uid 1000); Thu, 09 Nov 2023 13:59:33 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Nicholas Piggin , Ivan Warren , Richard Henderson , Michael Tokarev Subject: [Stable-7.2.7 12/62] accel/tcg: mttcg remove false-negative halted assertion Date: Thu, 9 Nov 2023 16:58:40 +0300 Message-Id: <20231109135933.1462615-12-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.2 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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+importer2=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, 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: , Errors-To: qemu-devel-bounces+importer2=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer2=patchew.org@nongnu.org X-ZM-MESSAGEID: 1699538523730100003 Content-Type: text/plain; charset="utf-8" From: Nicholas Piggin mttcg asserts that an execution ending with EXCP_HALTED must have cpu->halted. However between the event or instruction that sets cpu->halted and requests exit and the assertion here, an asynchronous event could clear cpu->halted. This leads to crashes running AIX on ppc/pseries because it uses H_CEDE/H_PROD hcalls, where H_CEDE sets self->halted =3D 1 and H_PROD sets other cpu->halted =3D 0 and kicks it. H_PROD could be turned into an interrupt to wake, but several other places in ppc, sparc, and semihosting follow what looks like a similar pattern setting halted =3D 0 directly. So remove this assertion. Reported-by: Ivan Warren Signed-off-by: Nicholas Piggin Message-Id: <20230829010658.8252-1-npiggin@gmail.com> [rth: Keep the case label and adjust the comment.] Signed-off-by: Richard Henderson (cherry picked from commit 0e5903436de712844b0e6cdd862b499c767e09e9) Signed-off-by: Michael Tokarev diff --git a/accel/tcg/tcg-accel-ops-mttcg.c b/accel/tcg/tcg-accel-ops-mttc= g.c index d50239e0e2..3a021624f4 100644 --- a/accel/tcg/tcg-accel-ops-mttcg.c +++ b/accel/tcg/tcg-accel-ops-mttcg.c @@ -100,14 +100,9 @@ static void *mttcg_cpu_thread_fn(void *arg) break; case EXCP_HALTED: /* - * during start-up the vCPU is reset and the thread is - * kicked several times. If we don't ensure we go back - * to sleep in the halted state we won't cleanly - * start-up when the vCPU is enabled. - * - * cpu->halted should ensure we sleep in wait_io_event + * Usually cpu->halted is set, but may have already been + * reset by another thread by the time we arrive here. */ - g_assert(cpu->halted); break; case EXCP_ATOMIC: qemu_mutex_unlock_iothread(); --=20 2.39.2