From nobody Sat Nov 15 19:43:37 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 Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1748174987690439.86291643054506; Sun, 25 May 2025 05:09:47 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uJAAL-0004kC-RM; Sun, 25 May 2025 08:09:22 -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 1uJA9o-0004X9-8W; Sun, 25 May 2025 08:08:48 -0400 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 1uJA9k-0003Fq-7s; Sun, 25 May 2025 08:08:46 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id 718DA124E51; Sun, 25 May 2025 15:08:17 +0300 (MSK) Received: from think4mjt.origo (mjtthink.wg.tls.msk.ru [192.168.177.146]) by tsrv.corpit.ru (Postfix) with ESMTP id 7F757215FB8; Sun, 25 May 2025 15:08:18 +0300 (MSK) From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, Ziqiao Kong , Alistair Francis , Richard Henderson , Michael Tokarev Subject: [Stable-10.0.1 31/59] target/riscv: fix endless translation loop on big endian systems Date: Sun, 25 May 2025 15:07:48 +0300 Message-Id: <20250525120818.273372-8-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.5 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+importer=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, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1748174989129116600 Content-Type: text/plain; charset="utf-8" From: Ziqiao Kong On big endian systems, pte and updated_pte hold big endian host data while pte_pa points to little endian target data. This means the branch at cpu_helper.c:1669 will be always satisfied and restart translation, causing an endless translation loop. The correctness of this patch can be deduced by: old_pte will hold value either from cpu_to_le32/64(pte) or cpu_to_le32/64(updated_pte), both of wich is litte endian. After that, an in-place conversion by le32/64_to_cpu(old_pte) ensures that old_pte now is in native endian, same with pte. Therefore, the endianness of the both side of if (old_pte !=3D pte) is correct. Signed-off-by: Ziqiao Kong Reviewed-by: Alistair Francis Reviewed-by: Richard Henderson Message-ID: <20250415080254.3667878-2-ziqiaokong@gmail.com> Signed-off-by: Alistair Francis Cc: qemu-stable@nongnu.org (cherry picked from commit ad63158bdb33dab5704ea1cf740d2ea0387175df) Signed-off-by: Michael Tokarev diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c index 6c4391d96b..3233b66e7e 100644 --- a/target/riscv/cpu_helper.c +++ b/target/riscv/cpu_helper.c @@ -1662,9 +1662,11 @@ static int get_physical_address(CPURISCVState *env, = hwaddr *physical, target_ulong *pte_pa =3D qemu_map_ram_ptr(mr->ram_block, addr1= ); target_ulong old_pte; if (riscv_cpu_sxl(env) =3D=3D MXL_RV32) { - old_pte =3D qatomic_cmpxchg((uint32_t *)pte_pa, pte, updat= ed_pte); + old_pte =3D qatomic_cmpxchg((uint32_t *)pte_pa, cpu_to_le3= 2(pte), cpu_to_le32(updated_pte)); + old_pte =3D le32_to_cpu(old_pte); } else { - old_pte =3D qatomic_cmpxchg(pte_pa, pte, updated_pte); + old_pte =3D qatomic_cmpxchg(pte_pa, cpu_to_le64(pte), cpu_= to_le64(updated_pte)); + old_pte =3D le64_to_cpu(old_pte); } if (old_pte !=3D pte) { goto restart; --=20 2.39.5